Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Resultados 1 - 20 de 73
Filtrar
1.
Nat Immunol ; 22(12): 1490-1502, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34616036

RESUMEN

Despite extensive studies into severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the effect of maternal infection on the neonate is unclear. To investigate this, we characterized the immunology of neonates born to mothers with confirmed SARS-CoV-2 infection during pregnancy. Here we show that maternal SARS-CoV-2 infection affects the neonatal immune system. Despite similar proportions of B cells, CD4+ T cells and CD8+ T cells, increased percentages of natural killer cells, Vδ2+ γδ T cells and regulatory T cells were detected in neonates born to mothers with recent or ongoing infection compared with those born to recovered or uninfected mothers. Increased plasma cytokine levels were also evident in neonates and mothers within the recent or ongoing infection group. Cytokine functionality was enhanced in neonates born to SARS-CoV-2-exposed mothers, compared to those born to uninfected mothers. In most neonates, this immune imprinting was nonspecific, suggesting vertical transmission of SARS-CoV-2 is limited, a finding supported by a lack of SARS-CoV-2-specific IgM in neonates despite maternal IgG transfer.


Asunto(s)
COVID-19/inmunología , Enfermedades del Recién Nacido/inmunología , Transmisión Vertical de Enfermedad Infecciosa , Complicaciones Infecciosas del Embarazo/inmunología , SARS-CoV-2/inmunología , Adulto , Anticuerpos Antivirales/inmunología , COVID-19/diagnóstico , COVID-19/virología , Citocinas/sangre , Citocinas/inmunología , Citocinas/metabolismo , Femenino , Humanos , Inmunidad Innata/inmunología , Inmunoglobulina G/inmunología , Recién Nacido , Enfermedades del Recién Nacido/diagnóstico , Enfermedades del Recién Nacido/virología , Células Asesinas Naturales/inmunología , Embarazo , Complicaciones Infecciosas del Embarazo/virología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , SARS-CoV-2/fisiología , Linfocitos T/inmunología , Linfocitos T/metabolismo , Linfocitos T Reguladores/inmunología
2.
Nature ; 601(7893): 422-427, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34987224

RESUMEN

Maternal morbidity and mortality continue to rise, and pre-eclampsia is a major driver of this burden1. Yet the ability to assess underlying pathophysiology before clinical presentation to enable identification of pregnancies at risk remains elusive. Here we demonstrate the ability of plasma cell-free RNA (cfRNA) to reveal patterns of normal pregnancy progression and determine the risk of developing pre-eclampsia months before clinical presentation. Our results centre on comprehensive transcriptome data from eight independent prospectively collected cohorts comprising 1,840 racially diverse pregnancies and retrospective analysis of 2,539 banked plasma samples. The pre-eclampsia data include 524 samples (72 cases and 452 non-cases) from two diverse independent cohorts collected 14.5 weeks (s.d., 4.5 weeks) before delivery. We show that cfRNA signatures from a single blood draw can track pregnancy progression at the placental, maternal and fetal levels and can robustly predict pre-eclampsia, with a sensitivity of 75% and a positive predictive value of 32.3% (s.d., 3%), which is superior to the state-of-the-art method2. cfRNA signatures of normal pregnancy progression and pre-eclampsia are independent of clinical factors, such as maternal age, body mass index and race, which cumulatively account for less than 1% of model variance. Further, the cfRNA signature for pre-eclampsia contains gene features linked to biological processes implicated in the underlying pathophysiology of pre-eclampsia.


Asunto(s)
Ácidos Nucleicos Libres de Células , Preeclampsia , ARN , Ácidos Nucleicos Libres de Células/sangre , Femenino , Humanos , Preeclampsia/diagnóstico , Preeclampsia/genética , Valor Predictivo de las Pruebas , Embarazo , ARN/sangre , Estudios Retrospectivos , Sensibilidad y Especificidad
3.
Acta Obstet Gynecol Scand ; 103(3): 512-521, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38009386

RESUMEN

INTRODUCTION: Spontaneous preterm birth prior to 32 weeks' gestation accounts for 1% of all deliveries and is associated with high rates of morbidity and mortality. A total of 70% are associated with chorioamnionitis which increases the incidence of morbidity, but for which there is no noninvasive antenatal test. Fetal adrenal glands produce cortisol and dehydroepiandosterone-sulphate which upregulate prior to spontaneous preterm birth. Ultrasound suggests that adrenal volumes may increase prior to preterm birth, but studies are limited. This study aimed to: (i) demonstrate reproducibility of magnetic resonance imaging (MRI) derived adrenal volumetry; (ii) derive normal ranges of total adrenal volumes, and adrenal: body volume for normal; (iii) compare with those who have spontaneous very preterm birth; and (iv) correlate with histopathological chorioamnionitis. MATERIAL AND METHODS: Patients at high risk of preterm birth prior to 32 weeks were prospectively recruited, and included if they did deliver prior to 32 weeks; a control group who delivered an uncomplicated pregnancy at term was also recruited. T2 weighted images of the entire uterus were obtained, and a deformable slice-to-volume method was used to reconstruct the fetal abdomen. Adrenal and body volumes were obtained via manual segmentation, and adrenal: body volume ratios generated. Normal ranges were created using control data. Differences between groups were investigated accounting for the effect of gestation by use of regression analysis. Placental histopathology was reviewed for pregnancies delivering preterm. RESULTS: A total of 56 controls and 26 cases were included in the analysis. Volumetry was consistent between observers. Adrenal volumes were not higher in the case group (p = 0.2); adrenal: body volume ratios were higher (p = 0.011), persisting in the presence of chorioamnionitis (p = 0.017). A cluster of three pairs of adrenal glands below the fifth centile were noted among the cases all of whom had a protracted period at risk of preterm birth prior to MRI. CONCLUSIONS: Adrenal: body volume ratios are significantly larger in fetuses who go on to deliver preterm than those delivering at term. Adrenal volumes were not significantly larger, we hypothesize that this could be due to an adrenal atrophy in fetuses with fulminating chorioamnionitis. A straightforward relationship of adrenal size being increased prior to preterm birth should not be assumed.


Asunto(s)
Corioamnionitis , Nacimiento Prematuro , Embarazo , Femenino , Humanos , Recién Nacido , Nacimiento Prematuro/diagnóstico por imagen , Corioamnionitis/diagnóstico por imagen , Proyectos Piloto , Reproducibilidad de los Resultados , Placenta , Feto
4.
Am J Obstet Gynecol ; 227(1): 72.e1-72.e16, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35398029

RESUMEN

BACKGROUND: Spontaneous preterm birth remains the main driver of childhood morbidity and mortality. Because of an incomplete understanding of the molecular pathways that result in spontaneous preterm birth, accurate predictive markers and target therapeutics remain elusive. OBJECTIVE: This study sought to determine if a cell-free RNA profile could reveal a molecular signature in maternal blood months before the onset of spontaneous preterm birth. STUDY DESIGN: Maternal samples (n=242) were obtained from a prospective cohort of individuals with a singleton pregnancy across 4 clinical sites at 12-24 weeks (nested case-control; n=46 spontaneous preterm birth <35 weeks and n=194 term controls). Plasma was processed via a next-generation sequencing pipeline for cell-free RNA using the Mirvie RNA platform. Transcripts that were differentially expressed in next-generation sequencing cases and controls were identified. Enriched pathways were identified in the Reactome database using overrepresentation analysis. RESULTS: Twenty five transcripts associated with an increased risk of spontaneous preterm birth were identified. A logistic regression model was developed using these transcripts to predict spontaneous preterm birth with an area under the curve =0.80 (95% confidence interval, 0.72-0.87) (sensitivity=0.76, specificity=0.72). The gene discovery and model were validated through leave-one-out cross-validation. A unique set of 39 genes was identified from cases of very early spontaneous preterm birth (<25 weeks, n=14 cases with time to delivery of 2.5±1.8 weeks); a logistic regression classifier on the basis of these genes yielded an area under the curve=0.76 (95% confidence interval, 0.63-0.87) in leave-one-out cross validation. Pathway analysis for the transcripts associated with spontaneous preterm birth revealed enrichment of genes related to collagen or the extracellular matrix in those who ultimately had a spontaneous preterm birth at <35 weeks. Enrichment for genes in insulin-like growth factor transport and amino acid metabolism pathways were associated with spontaneous preterm birth at <25 weeks. CONCLUSION: Second trimester cell-free RNA profiles in maternal blood provide a noninvasive window to future occurrence of spontaneous preterm birth. The systemic finding of changes in collagen and extracellular matrix pathways may serve to identify individuals at risk for premature cervical remodeling, with growth factor and metabolic pathways implicated more often in very early spontaneous preterm birth. The use of cell-free RNA profiles has the potential to accurately identify those at risk for spontaneous preterm birth by revealing the underlying pathophysiology, creating an opportunity for more targeted therapeutics and effective interventions.


Asunto(s)
Ácidos Nucleicos Libres de Células , Nacimiento Prematuro , Ácidos Nucleicos Libres de Células/genética , Cuello del Útero , Femenino , Humanos , Recién Nacido , Embarazo , Nacimiento Prematuro/genética , Estudios Prospectivos , ARN
5.
Prenat Diagn ; 42(8): 1049-1058, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35670265

RESUMEN

Chorioamnionitis is present in up to 70% of spontaneous preterm births. It is defined as an acute inflammation of the chorion, with or without involvement of the amnion, and is evidence of a maternal immunological response to infection. A fetal inflammatory response can coexist and is diagnosed on placental histopathology postnatally. Fetal inflammatory response syndrome (FIRS) is associated with poorer fetal and neonatal outcomes. The only antenatal diagnostic test is amniocentesis which carries risks of miscarriage or preterm birth. Imaging of the fetal immune system, in particular the thymus and the spleen, and the placenta may give valuable information antenatally regarding the diagnosis of fetal inflammatory response. While ultrasound is largely limited to structural information, MRI can complement this with functional information that may provide insight into the metabolic activities of the fetal immune system and placenta. This review discusses fetal and placental imaging in pregnancies complicated by chorioamnionitis and their potential future use in achieving non-invasive antenatal diagnosis.


Asunto(s)
Corioamnionitis , Nacimiento Prematuro , Amniocentesis , Corioamnionitis/diagnóstico por imagen , Femenino , Enfermedades Fetales , Humanos , Recién Nacido , Placenta/diagnóstico por imagen , Placenta/patología , Embarazo , Síndrome de Respuesta Inflamatoria Sistémica
6.
PLoS Med ; 18(7): e1003689, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-34228735

RESUMEN

BACKGROUND: Preterm delivery (before 37 weeks of gestation) is the single most important contributor to neonatal death and morbidity, with lifelong repercussions. However, the majority of women who present with preterm labour (PTL) symptoms do not deliver imminently. Accurate prediction of PTL is needed in order ensure correct management of those most at risk of preterm birth (PTB) and to prevent the maternal and fetal risks incurred by unnecessary interventions given to the majority. The QUantitative Innovation in Predicting Preterm birth (QUIPP) app aims to support clinical decision-making about women in threatened preterm labour (TPTL) by combining quantitative fetal fibronectin (qfFN) values, cervical length (CL), and significant PTB risk factors to create an individualised percentage risk of delivery. METHODS AND FINDINGS: EQUIPTT was a multi-centre cluster randomised controlled trial (RCT) involving 13 maternity units in South and Eastern England (United Kingdom) between March 2018 and February 2019. Pregnant women (n = 1,872) between 23+0 and 34+6 weeks' gestation with symptoms of PTL in the analysis period were assigned to either the intervention (762) or control (1,111). The mean age of the study population was 30.2 (+/- SD 5.93). A total of 56.0% were white, 19.6% were black, 14.2% were Asian, and 10.2% were of other ethnicities. The intervention was the use of the QUiPP app with admission, antenatal corticosteroids (ACSs), and transfer advised for women with a QUiPP risk of delivery >5% within 7 days. Control sites continued with their conventional management of TPTL. Unnecessary management for TPTL was a composite primary outcome defined by the sum of unnecessary admission decisions (admitted and delivery interval >7 days or not admitted and delivery interval ≤7 days) and the number of unnecessary in utero transfer (IUT) decisions/actions (IUT that occurred or were attempted >7 days prior to delivery) and ex utero transfers (EUTs) that should have been in utero (attempted and not attempted). Unnecessary management of TPTL was 11.3% (84/741) at the intervention sites versus 11.5% (126/1094) at control sites (odds ratio [OR] 0.97, 95% confidence interval [CI] 0.66-1.42, p = 0.883). Control sites frequently used qfFN and did not follow UK national guidance, which recommends routine treatment below 30 weeks without testing. Unnecessary management largely consisted of unnecessary admissions which were similar at intervention and control sites (10.7% versus 10.8% of all visits). In terms of adverse outcomes for women in TPTL <36 weeks, 4 women from the intervention sites and 12 from the control sites did not receive recommended management. If the QUiPP percentage risk was used as per protocol, unnecessary management would have been 7.4% (43/578) versus 9.9% (134/1,351) (OR 0.72, 95% CI 0.45-1.16). Our external validation of the QUiPP app confirmed that it was highly predictive of delivery in 7 days; receiver operating curve area was 0.90 (95% CI 0.85-0.95) for symptomatic women. Study limitations included a lack of compliance with national guidance at the control sites and difficulties in implementation of the QUiPP app. CONCLUSIONS: This cluster randomised trial did not demonstrate that the use of the QUiPP app reduced unnecessary management of TPTL compared to current management but would safely improve the management recommended by the National Institute for Health and Care Excellence (NICE). Interpretation of qfFN, with or without the QUiPP app, is a safe and accurate method for identifying women most likely to benefit from PTL interventions. TRIAL REGISTRATION: ISRCTN Registry ISRCTN17846337.


Asunto(s)
Aplicaciones Móviles , Trabajo de Parto Prematuro/diagnóstico , Trabajo de Parto Prematuro/prevención & control , Adulto , Femenino , Humanos , Embarazo
7.
Biochem Soc Trans ; 49(2): 997-1011, 2021 04 30.
Artículo en Inglés | MEDLINE | ID: mdl-33860781

RESUMEN

Cyclic adenosine monophosphate (cAMP) contributes to maintenance of a quiescent (relaxed) state in the myometrium (i.e. uterine smooth muscle) during pregnancy, which most commonly has been attributed to activation of protein kinase A (PKA). PKA-mediated phosphorylation of cytosolic contractile apparatus components in myometrial smooth muscle cells (mSMCs) are known to promote relaxation. Additionally, PKA also regulates nuclear transcription factor (TF) activity to control expression of genes important to the labour process; these are mostly involved in actin-myosin interactions, cell-to-cell connectivity and inflammation, all of which influence mSMC transition from a quiescent to a contractile (pro-labour) phenotype. This review focuses on the evidence that cAMP modulates the activity of TFs linked to pro-labour gene expression, predominantly cAMP response element (CRE) binding TFs, nuclear factor κB (NF-κB), activator protein 1 (AP-1) family and progesterone receptors (PRs). This review also considers the more recently described exchange protein directly activated by cAMP (EPAC) that may oppose the pro-quiescent effects of PKA, as well as explores findings from other cell types that have the potential to be of novel relevance to cAMP action on TF function in the myometrium.


Asunto(s)
AMP Cíclico/metabolismo , Regulación de la Expresión Génica , Músculo Liso/metabolismo , Miometrio/metabolismo , Parto/genética , Factores de Transcripción/genética , Proteínas Quinasas Dependientes de AMP Cíclico/genética , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Femenino , Humanos , Trabajo de Parto/genética , Trabajo de Parto/metabolismo , FN-kappa B/genética , FN-kappa B/metabolismo , Parto/metabolismo , Embarazo , Factores de Transcripción/metabolismo
8.
Acta Obstet Gynecol Scand ; 100(12): 2244-2252, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34546571

RESUMEN

INTRODUCTION: Preterm prelabor rupture of membranes (PPROM) complicates 3% of pregnancies in the UK. Where delivery does not occur spontaneously, expectant management until 37 weeks of gestation is advocated, unless signs of maternal infection develop. However, clinical presentation of maternal infection can be a late sign and injurious fetal inflammatory responses may already have been activated. There is therefore a need for more sensitive markers to aid optimal timing of interventions. At present there is no non-invasive test in clinical practice to assess for infection in the fetal compartment and definitive diagnosis of chorioamnionitis is by histological assessment of the placenta after delivery. This study presents comprehensive functional placental magnetic resonance imaging (MRI) quantification, already used in other organ systems, to assess for infection/inflammation, in women with and without PPROM aiming to explore its use as a biomarker for inflammation within the feto-placental compartment in vivo. MATERIAL AND METHODS: Placental MRI scans were performed in a cohort of 12 women (with one having two scans) with PPROM before 34 weeks of gestation (selected because of their high risk of infection), and in a control group of 87 women. Functional placental assessment was performed with magnetic resonance techniques sensitive to changes in the microstructure (diffusion) and tissue composition (relaxometry), with quantification performed both over the entire organ and in regions of interest between the basal and chorionic plate. Placental histology was analyzed after delivery where available. RESULTS: Normative evolution of functional magnetic resonance biomarkers over gestation was studied. Cases of inflammation, as assessed by histological presence of chorioamnionitis, and umbilical cord vasculitis with or without funisitis, were associated with lower T2* (mean T2* at 30 weeks 50 ms compared with 58 ms in controls) and higher fractional anisotropy (mean at 30 weeks 0.55 compared with 0.45 in controls). These differences did not reach significance and there was substantial heterogeneity both in T2* and Apparent Diffusivitiy across the cohort. CONCLUSIONS: This first exploration of functional placental assessment in a cohort of women with PPROM demonstrates that functional placental MRI can reveal a range of placental changes associated with inflammatory processes. It is a promising tool to gain information and in the future to identify inflammation in vivo, and could therefore assist in improving optimal timing for interventions designed to prevent fetal injury.


Asunto(s)
Rotura Prematura de Membranas Fetales/diagnóstico por imagen , Diagnóstico Prenatal , Adulto , Femenino , Humanos , Londres , Imagen por Resonancia Magnética , Proyectos Piloto , Embarazo , Estudios Prospectivos , Centros de Atención Terciaria
9.
Acta Obstet Gynecol Scand ; 100(6): 1040-1050, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-32865812

RESUMEN

INTRODUCTION: Infection and inflammation have been implicated in the etiology and subsequent morbidity associated with preterm birth. At present, there are no tests to assess for fetal compartment infection. The thymus, a gland integral in the fetal immune system, has been shown to involute in animal models of antenatal infection, but its response in human fetuses has not been studied. This study aims: (a) to generate magnetic resonance imaging (MRI) -derived fetal thymus volumes standardized for fetal weight; (b) to compare standardized thymus volumes from fetuses that delivered before 32 weeks of gestation with fetuses that subsequently deliver at term; (c) to assess thymus size as a predictor of preterm birth; and (d) to correlate the presence of chorioamnionitis and funisitis at delivery with thymic volumes in utero in fetuses that subsequently deliver preterm. MATERIAL AND METHODS: Women at high-risk of preterm birth at 20-32 weeks of gestation were recruited. A control group was obtained from existing data sets acquired as part of three research studies. A fetal MRI was performed on a 1.5T or 3T MRI scanner: T2 weighted images were obtained of the entire uterine content and specifically the fetal thorax. A slice-to-volume registration method was used for reconstruction of three-dimensional images of the thorax. Thymus segmentations were performed manually. Body volumes were calculated by manual segmentation and thymus:body volume ratios were generated. Comparison of groups was performed using multiple regression analysis. Normal ranges were created for thymus volume and thymus:body volume ratios using the control data. Receiver operating curves (ROC) curves were generated for thymus:body volume ratio and gestation-adjusted thymus volume centiles as predictors of preterm birth. Placental histology was analyzed where available from pregnancies that delivered very preterm and the presence of chorioamnionitis/funisitis was noted. RESULTS: Normative ranges were created for thymus volume, and thymus volume was standardized for fetal size from fetuses that subsequently delivered at term, but were imaged at 20-32 weeks of gestation. Image data sets from 16 women that delivered <32 weeks of gestation (ten with ruptured membranes and six with intact membranes) and 80 control women that delivered >37 weeks were included. Mean gestation at MRI of the study group was 28+4  weeks (SD 3.2) and for the control group was 25+5  weeks (SD 2.4). Both absolute fetal thymus volumes and thymus:body volume ratios were smaller in fetuses that delivered preterm (P < .001). Of the 16 fetuses that delivered preterm, 13 had placental histology, 11 had chorioamnionitis, and 9 had funisitis. The strongest predictors of prematurity were the thymus volume Z-score and thymus:body volume ratio Z-score (ROC areas 0.915 and 0.870, respectively). CONCLUSIONS: We have produced MRI-derived normal ranges for fetal thymus and thymus:body volume ratios between 20 and 32 weeks of gestation. Fetuses that deliver very preterm had reduced thymus volumes when standardized for fetal size. A reduced thymus volume was also a predictor of spontaneous preterm delivery. Thymus volume may be a suitable marker of the fetal inflammatory response, although further work is needed to assess this, increasing the sample size to correlate the extent of chorioamnionitis with thymus size.


Asunto(s)
Nacimiento Prematuro/diagnóstico por imagen , Timo/diagnóstico por imagen , Timo/fisiología , Ultrasonografía Prenatal/métodos , Adulto , Estudios de Casos y Controles , Femenino , Rotura Prematura de Membranas Fetales/diagnóstico por imagen , Edad Gestacional , Humanos , Recién Nacido , Imagen por Resonancia Magnética , Tamaño de los Órganos/fisiología , Proyectos Piloto , Embarazo , Embarazo de Alto Riesgo , Timo/embriología , Timo/patología
10.
PLoS Med ; 17(10): e1003350, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-33022010

RESUMEN

BACKGROUND: Midwifery continuity of care is the only health system intervention shown to reduce preterm birth (PTB) and improve perinatal survival, but no trial evidence exists for women with identified risk factors for PTB. We aimed to assess feasibility, fidelity, and clinical outcomes of a model of midwifery continuity of care linked with a specialist obstetric clinic for women considered at increased risk for PTB. METHODS AND FINDINGS: We conducted a hybrid implementation-effectiveness, randomised, controlled, unblinded, parallel-group pilot trial at an inner-city maternity service in London (UK), in which pregnant women identified at increased risk of PTB were randomly assigned (1:1) to either midwifery continuity of antenatal, intrapartum, and postnatal care (Pilot study Of midwifery Practice in Preterm birth Including women's Experiences [POPPIE] group) or standard care group (maternity care by different midwives working in designated clinical areas). Pregnant women attending for antenatal care at less than 24 weeks' gestation were eligible if they fulfilled one or more of the following criteria: previous cervical surgery, cerclage, premature rupture of membranes, PTB, or late miscarriage; previous short cervix or short cervix this pregnancy; or uterine abnormality and/or current smoker of tobacco. Feasibility outcomes included eligibility, recruitment and attrition rates, and fidelity of the model. The primary outcome was a composite of appropriate and timely interventions for the prevention and/or management of preterm labour and birth. We analysed by intention to treat. Between 9 May 2017 and 30 September 2018, 334 women were recruited; 169 women were allocated to the POPPIE group and 165 to the standard group. Mean maternal age was 31 years; 32% of the women were from Black, Asian, and ethnic minority groups; 70% were in employment; and 46% had a university degree. Nearly 70% of women lived in areas of social deprivation. More than a quarter of women had at least one pre-existing medical condition and multiple risk factors for PTB. More than 75% of antenatal and postnatal visits were provided by a named/partner midwife, and a midwife from the POPPIE team was present at 80% of births. The incidence of the primary composite outcome showed no statistically significant difference between groups (POPPIE group 83.3% versus standard group 84.7%; risk ratio 0.98 [95% confidence interval (CI) 0.90 to 1.08]; p = 0.742). Infants in the POPPIE group were significantly more likely to have skin-to-skin contact after birth, to have it for a longer time, and to breastfeed immediately after birth and at hospital discharge. There were no differences in other secondary outcomes. The number of serious adverse events was similar in both groups and unrelated to the intervention (POPPIE group 6 versus standard group 5). Limitations of this study included the limited power and the nonmasking of group allocation; however, study assignment was masked to the statistician and researchers who analysed the data. CONCLUSIONS: In this study, we found that it is feasible to set up and achieve fidelity of a model of midwifery continuity of care linked with specialist obstetric care for women at increased risk of PTB in an inner-city maternity service in London (UK), but there is no impact on most outcomes for this population group. Larger appropriately powered trials are needed, including in other settings, to evaluate the impact of relational continuity and hypothesised mechanisms of effect based on increased trust and engagement, improved care coordination, and earlier referral on disadvantaged communities, including women with complex social factors and social vulnerability. TRIAL REGISTRATION: We prospectively registered the pilot trial on the UK Clinical Research Network Portfolio Database (ID number: 31951, 24 April 2017). We registered the trial on the International Standard Randomised Controlled Trial Number (ISRCTN) (Number: 37733900, 21 August 2017) and before trial recruitment was completed (30 September 2018) when informed that prospective registration for a pilot trial was also required in a primary clinical trial registry recognised by WHO and the International Committee of Medical Journal Editors (ICMJE). The protocol as registered and published has remained unchanged, and the analysis conforms to the original plan.


Asunto(s)
Continuidad de la Atención al Paciente/organización & administración , Atención Posnatal/métodos , Atención Prenatal/métodos , Adulto , Cesárea , Etnicidad , Femenino , Edad Gestacional , Humanos , Lactante , Recién Nacido , Edad Materna , Servicios de Salud Materna/tendencias , Partería/tendencias , Grupos Minoritarios , Trabajo de Parto Prematuro , Obstetricia , Parto , Proyectos Piloto , Embarazo , Nacimiento Prematuro/prevención & control , Estudios Prospectivos , Distribución Aleatoria , Reino Unido/epidemiología
11.
Reprod Health ; 17(Suppl 1): 54, 2020 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-32354368

RESUMEN

BACKGROUND AND OBJECTIVE: PRECISE is a population-based, prospective pregnancy cohort study designed for deep phenotyping of pregnancies in women with placenta-related disorders, and in healthy controls. The PRECISE Network is recruiting ~ 10,000 pregnant women in three countries (The Gambia, Kenya, and Mozambique) representing sub-Saharan Africa. The principal aim is to improve our understanding of pre-eclampsia, fetal growth restriction and stillbirth. This involves the creation of a highly curated biorepository for state of the art discovery science and a rich database of antenatal variables and maternal and neonatal outcomes. Our overarching aim is to provide large sample numbers with adequate power to address key scientific questions. Here we describe our experience of establishing a biorepository in the PRECISE Network and review the issues and challenges surrounding set-up, management and scientific use. METHODS: The feasibility of collecting and processing each sample type was assessed in each setting and plans made for establishing the necessary infrastructure. Quality control (QC) protocols were established to ensure that biological samples are 'fit-for-purpose'. The management structures required for standardised sample collection and processing were developed. This included the need for transport of samples between participating countries and to external academic/commercial institutions. RESULTS: Numerous practical challenges were encountered in setting up the infrastructure including facilities, staffing, training, cultural barriers, procurement, shipping and sample storage. Whilst delaying the project, these were overcome by establishing good communication with the sites, training workshops and constant engagement with the necessary commercial suppliers. A Project Executive Committee and Biology Working Group together defined the biospecimens required to answer the research questions paying particular attention to harmonisation of protocols with other cohorts so as to enable cross-biorepository collaboration. Governance structures implemented include a Data and Sample Committee to ensure biospecimens and data will be used according to consent, and prioritisation by scientific excellence. A coordinated sample and data transfer agreement will prevent delay in sample sharing. DISCUSSION: With adequate training and infrastructure, it is possible to establish high quality sample collections to facilitate research programmes such as the PRECISE Network in sub-Saharan Africa. These preparations are pre-requisites for effective execution of a biomarker-based approach to better understand the complexities of placental disease in these settings, and others.


Asunto(s)
Retardo del Crecimiento Fetal , Preeclampsia , Mortinato , Bancos de Tejidos , Niño , Estudios de Cohortes , Femenino , Gambia , Humanos , Recién Nacido , Kenia , Masculino , Mozambique , Embarazo , Estudios Prospectivos
12.
Reprod Health ; 17(Suppl 1): 51, 2020 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-32354357

RESUMEN

BACKGROUND: The PRECISE (PREgnancy Care Integrating translational Science, Everywhere) Network is a new and broadly-based group of research scientists and health advocates based in the UK, Africa and North America. METHODS: This paper describes the protocol that underpins the clinical research activity of the Network, so that the investigators, and broader global health community, can have access to 'deep phenotyping' (social determinants of health, demographic and clinical parameters, placental biology and agnostic discovery biology) of women as they advance through pregnancy to the end of the puerperium, whether those pregnancies have normal outcomes or are complicated by one/more of the placental disorders of pregnancy (pregnancy hypertension, fetal growth restriction and stillbirth). Our clinical sites are in The Gambia (Farafenni), Kenya (Kilifi County), and Mozambique (Maputo Province). In each country, 50 non-pregnant women of reproductive age will be recruited each month for 1 year, to provide a final national sample size of 600; these women will provide culturally-, ethnically-, seasonally- and spatially-relevant control data with which to compare women with normal and complicated pregnancies. Between the three countries we will recruit ≈10,000 unselected pregnant women over 2 years. An estimated 1500 women will experience one/more placental complications over the same epoch. Importantly, as we will have accurate gestational age dating using the TraCer device, we will be able to discriminate between fetal growth restriction and preterm birth. Recruitment and follow-up will be primarily facility-based and will include women booking for antenatal care, subsequent visits in the third trimester, at time-of-disease, when relevant, during/immediately after birth and 6 weeks after birth. CONCLUSIONS: To accelerate progress towards the women's and children's health-relevant Sustainable Development Goals, we need to understand how a variety of social, chronic disease, biomarker and pregnancy-specific determinants health interact to result in either a resilient or a compromised pregnancy for either mother or fetus/newborn, or both. This protocol has been designed to create such a depth of understanding. We are seeking funding to maintain the cohort to better understand the implications of pregnancy complications for both maternal and child health.


Asunto(s)
Placenta , Atención Prenatal , Determinantes Sociales de la Salud , Niño , Femenino , Gambia , Humanos , Recién Nacido , Kenia , Masculino , Mozambique , Embarazo , Resultado del Embarazo , Nacimiento Prematuro , Investigación Biomédica Traslacional
13.
Matern Child Nutr ; 16(2): e12914, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31777183

RESUMEN

There is evidence that caesarean section delivery can impact on neonatal weight loss and weight gain patterns in the first 5 days of life. We conducted an integrative systematic review to examine the association of mode of delivery on early neonatal weight loss. Pubmed, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Excerpta Medica dataBASE, and Medical Literature Analysis and Retrieval System Online were searched for relevant papers published before June 2019. Reference lists from the relevant papers were then backwards and forwards searched. As neonatal weight loss was reported in different formats, a meta-analysis could not be carried out. Most studies did not distinguish between elective and emergency caesarean sections or instrumental and nonassisted vaginal deliveries. Seven papers were included. All papers except one found that caesarean section was associated with higher weight loss in the early days of life. Two papers presented data from studies on babies followed up to 1 month. One study found that on day 25, babies born by caesarean section had significantly higher weight gain than those born vaginally, while another found that by day 28, babies born vaginally gained more weight per day (11.9 g/kg/day) than those born by caesarean section (10.9 g/kg/day; p = .02). Overall, infants born by caesarean section lost more weight than those born vaginally, but due to the small number of studies included, more are needed to look at this difference and why it may occur. This discrepancy in weight between the two groups may be corrected over time, but future studies will need larger sample sizes and longer follow-up periods to examine this.


Asunto(s)
Cesárea/métodos , Cesárea/estadística & datos numéricos , Fenómenos Fisiológicos Nutricionales del Lactante/fisiología , Aumento de Peso/fisiología , Pérdida de Peso/fisiología , Femenino , Humanos , Recién Nacido , Masculino
14.
Lancet ; 392(10155): 1349-1357, 2018 10 13.
Artículo en Inglés | MEDLINE | ID: mdl-30322585

RESUMEN

A caesarean section (CS) can be a life-saving intervention when medically indicated, but this procedure can also lead to short-term and long-term health effects for women and children. Given the increasing use of CS, particularly without medical indication, an increased understanding of its health effects on women and children has become crucial, which we discuss in this Series paper. The prevalence of maternal mortality and maternal morbidity is higher after CS than after vaginal birth. CS is associated with an increased risk of uterine rupture, abnormal placentation, ectopic pregnancy, stillbirth, and preterm birth, and these risks increase in a dose-response manner. There is emerging evidence that babies born by CS have different hormonal, physical, bacterial, and medical exposures, and that these exposures can subtly alter neonatal physiology. Short-term risks of CS include altered immune development, an increased likelihood of allergy, atopy, and asthma, and reduced intestinal gut microbiome diversity. The persistence of these risks into later life is less well investigated, although an association between CS use and greater incidence of late childhood obesity and asthma are frequently reported. There are few studies that focus on the effects of CS on cognitive and educational outcomes. Understanding potential mechanisms that link CS with childhood outcomes, such as the role of the developing neonatal microbiome, has potential to inform novel strategies and research for optimising CS use and promote optimal physiological processes and development.


Asunto(s)
Cesárea/efectos adversos , Cesárea/mortalidad , Cesárea/psicología , Femenino , Salud Global , Humanos , Recién Nacido , Pobreza , Embarazo , Resultado del Embarazo/epidemiología , Factores de Riesgo
15.
Am J Obstet Gynecol ; 221(4): 341.e1-341.e9, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31132343

RESUMEN

BACKGROUND: Congenital uterine anomalies are associated with late miscarriage and spontaneous preterm birth. OBJECTIVE: Our aim was 1) to determine the rate of spontaneous preterm birth in each type of congenital uterine anomaly, and 2) to assess the performance of quantitative fetal fibronectin and cervical length measurement by transvaginal ultrasound in asymptomatic women with congenital uterine anomalies for the prediction of spontaneous preterm birth at <34 and <37 weeks of gestation. MATERIALS AND METHODS: This was a retrospective cohort of women with congenital uterine anomalies asymptomatic for spontaneous preterm birth, from 4 tertiary referral centers in the United Kingdom (2001-2016). Congenital uterine anomalies were categorized into fusion (unicornuate, didelphic, and bicornuate uteri) or resorption defects (septate, with or without resection, and arcuate uteri), based on prepregnancy diagnosis. All women underwent serial transvaginal ultrasound cervical length assessment in the second trimester (16 to 24 weeks' gestation); a subgroup underwent quantitative fetal fibronectin testing from 18 weeks' gestation. We investigated the relationship between congenital uterine anomalies and predictive test performance for spontaneous preterm birth at <34 and <37 weeks' gestation. RESULTS: A total of 319 women were identified as having congenital uterine anomalies in our high-risk population. Of the women, 7% (23/319) delivered spontaneously at <34 weeks' gestation and 18% (56/319) at <37 weeks' gestation. Rates of spontaneous preterm birth by type were as follows: 26% (7/27) for unicornuate, 21% (7/34) for didelphic, 16% (31/189) for bicornuate, 13% (7/56) for septate, and 31% (4/13) for arcuate. In all, 80% (45/56) of women who had spontaneous preterm birth at <37 weeks did not develop a short cervical length (<25 mm) during the surveillance period (16-24 weeks). The diagnostic accuracy of short cervical length had a low sensitivity (20.3) for predicting spontaneous preterm birth at <34 weeks. Cervical length had an area under the receiver operating curve of 0.56 (95% confidence interval, 0.48-0.64) and 0.59 (95% confidence interval, 0.55-0.64) for prediction of spontaneous preterm birth at <34 and <37 weeks, respectively. The area under the curve for cervical length to predict spontaneous preterm birth at <34 weeks was 0.48 for fusion defects (95% confidence interval, 0.39-0.57) but 0.78 (95% confidence interval, 0.66-0.91) for women with resorption defects. Overall quantitative fetal fibronectin had an area under the curve of 0.63 (95% confidence interval, 0.49-0.77) and 0.58 (95% confidence interval, 0.49- 0.68) for prediction of spontaneous preterm birth at <34 and <37 weeks, respectively. The area under the curve for prediction of spontaneous preterm birth at <37 weeks with quantitative fetal fibronectin for fusion defects was 0.52 (95% confidence interval, 0.41-0.63) but 0.79 (95% confidence interval, 0.63-0.95) for women with resorption defects. Results were similar when women with intervention were excluded. CONCLUSION: The commonly used markers cervical length and quantitative fetal fibronectin have utility in prediction of spontaneous preterm birth in resorption congenital uterine defects but not in fusion defects. This is contrary to findings in other high-risk populations. These findings need to be accounted for when planning antenatal care, and have potential implications for predictive tests used in spontaneous preterm birth surveillance and intervention.


Asunto(s)
Medición de Longitud Cervical , Fibronectinas/análisis , Complicaciones del Embarazo/epidemiología , Nacimiento Prematuro/epidemiología , Anomalías Urogenitales/epidemiología , Enfermedades Uterinas/epidemiología , Útero/anomalías , Adulto , Área Bajo la Curva , Enfermedades Asintomáticas , Estudios de Cohortes , Femenino , Humanos , Embarazo , Segundo Trimestre del Embarazo , Curva ROC , Estudios Retrospectivos , Medición de Riesgo , Reino Unido/epidemiología , Enfermedades Uterinas/congénito
16.
BMC Pregnancy Childbirth ; 19(1): 68, 2019 Feb 13.
Artículo en Inglés | MEDLINE | ID: mdl-30760248

RESUMEN

BACKGROUND: Accurate diagnosis of preterm labour is needed to ensure correct management of those most at risk of preterm birth and to prevent the maternal and fetal risks incurred by unnecessary interventions given to the large majority of women, who do not deliver within a week of presentation. Intervention "just-in-case" results in many avoidable admissions, women being transferred out of their local hospital unnecessarily and most women receiving unwarranted drugs, such as steroids and tocolytics. It also precludes appropriate transfers for others as neonatal cots are blocked pre-emptively, resulting in more dangerous ex-utero transfers. We have developed the QUiPP App which is a clinical decision-making aid based on previous outcomes of women, quantitative fetal fibronectin (qfFN) values and cervical length. It is hypothesised that using the QUiPP app will reduce inappropriate admissions and transfers. METHODS: A multi-site cluster randomised trial will evaluate whether the QUiPP app reduces inappropriate management for threatened preterm labour. The 13 participating centres will be randomly allocated to receive either intervention or control. If the QUiPP app calculates risk of delivery within 7 days to be is less than 5%, clinicians are advised that interventions may be withheld. Women's experience of threatened preterm labour assessment will be explored using self-completed questionnaires, with a subset of participants being invited to semi-structured interview. A health economics analysis is also planned. DISCUSSION: We hypothesise that the QUiPP app will improve identification of the most appropriate women for admission and transfer and ensure that therapies known to reduce risk of preterm neonatal morbidities are offered to those who need them. We will determine which women do not require these therapies, thereby reducing over-medicalisation and the associated maternal and fetal risks for these women. The findings will inform future national guidelines on threatened preterm labour. Beyond obstetrics, evaluating the impact of an app in an emergency setting, and our emphasis on balancing harms of over-treatment as well as under-treatment, make EQUIPTT a valuable contribution to translational medicine. TRIAL REGISTRATION: The EQUIPTT trial was prospectively registered on 16th January 2018 with the ISRCTN registry (no. 17846337 ).


Asunto(s)
Toma de Decisiones Clínicas/métodos , Fibronectinas/sangre , Trabajo de Parto Prematuro/prevención & control , Diagnóstico Prenatal/métodos , Medición de Longitud Cervical , Femenino , Humanos , Recién Nacido , Masculino , Estudios Multicéntricos como Asunto , Trabajo de Parto Prematuro/sangre , Embarazo , Ensayos Clínicos Controlados Aleatorios como Asunto , Proyectos de Investigación , Medición de Riesgo , Triaje
17.
BMC Med Inform Decis Mak ; 19(1): 219, 2019 11 12.
Artículo en Inglés | MEDLINE | ID: mdl-31718627

RESUMEN

BACKGROUND: The use of digital technology in healthcare has been found to be useful for data collection, provision of health information and communications. Despite increasing use of medical mobile phone applications (apps), by both clinicians and patients, there appears to be a paucity of peer-reviewed publications evaluating their use, particularly in pregnancy. This scoping review explored the use of mobile phone apps for clinical decision support in pregnancy. Specific objectives were to: 1. determine the current landscape of mobile phone app use for clinical decision support in pregnancy; 2. identify perceived benefits and potential hazards of use and 3. identify facilitators and barriers to implementation of these apps into clinical practice. METHODS: Papers eligible for inclusion were primary research or reports on the development and evaluation of apps for use by clinicians for decision support in pregnancy, published in peer-reviewed journals. Research databases included Medline, Embase, PsychoInfo, the Cochrane Database of Systematic Reviews and the online digital health journals JMIR mHealth and uHealth. Charting and thematic analysis was undertaken using NVivo qualitative data management software and the Framework approach. RESULTS: After screening for eligibility, 13 papers were identified, mainly reporting early stage development of the mobile app, and feasibility or acceptability studies designed to inform further development. Thematic analysis revealed four main themes across the included papers: 1. acceptability and satisfaction; 2. ease of use and portability; 3. multi-functionality and 4. the importance of user involvement in development and evaluation. CONCLUSIONS: This review highlights the benefits of mobile apps for clinical decision support in pregnancy and potential barriers to implementation, but reveals a lack of rigorous reporting of evaluation of their use and data security. This situation may change, however, following the issue of FDA and MHRA guidelines and implementation of UK government and other international strategies. Overall, the findings suggest that ease of use, portability and multi-functionality make mobile apps for clinical decision support in pregnancy useful and acceptable tools for clinicians.


Asunto(s)
Teléfono Celular , Sistemas de Apoyo a Decisiones Clínicas , Aplicaciones Móviles , Telemedicina , Femenino , Humanos , Embarazo
18.
BMC Pregnancy Childbirth ; 18(1): 335, 2018 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-30119660

RESUMEN

BACKGROUND: Despite much research effort, there is a paucity of conclusive evidence in the field of preterm birth prediction and prevention. The methods of monitoring and prevention strategies offered to women at risk vary considerably around the UK and depend on local maternity care provision. It is becoming increasingly recognised that this experience and knowledge, if captured on a larger scale, could be a utilized as a valuable source of evidence for others. The UK Preterm Clinical Network (UKPCN) was established with the aim of improving care and outcomes for women at risk of preterm birth through the sharing of a wealth of experience and knowledge, as well as the building of clinical and research collaboration. The design and development of a bespoke internet-based database was fundamental to achieving this aim. METHOD: Following consultation with UKPCN members and agreement on a minimal dataset, the Preterm Clinical Network (PCN) Database was constructed to collect data from women at risk of preterm birth and their children. Information Governance and research ethics committee approval was given for the storage of historical as well as prospectively collected data. Collaborating centres have instant access to their own records, while use of pooled data is governed by the PCN Database Access Committee. Applications are welcomed from UKPCN members and other established research groups. The results of investigations using the data are expected to provide insights into the effectiveness of current surveillance practices and preterm birth interventions on a national and international scale, as well as the generation of ideas for innovation and research. To date, 31 sites are registered as Data Collection Centres, four of which are outside the UK. CONCLUSION: This paper outlines the aims of the PCN Database along with the development process undertaken from the initial idea to live launch.


Asunto(s)
Recolección de Datos/métodos , Bases de Datos Factuales , Nacimiento Prematuro/epidemiología , Atención Prenatal/métodos , Femenino , Humanos , Internet , Embarazo , Medición de Riesgo/métodos , Reino Unido
19.
Reprod Health ; 15(1): 215, 2018 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-30577831

RESUMEN

BACKGROUND: In India, 3.6 million pregnancies are affected by preterm birth annually, with many infants dying or surviving with disability. Currently, there is no simple test available for screening all women at risk of spontaneous PTB in low income setting, although high resource settings routinely use cervical length measurement and cervico-vaginal fluid fetal fibronectin for identification and care of women at risk due to clinical history. In rural India, where the public health system has limited infrastructure, trained staff and equipment, there is a greater need to develop a low-cost screening approach for providing early referral, treatment and remedial support for pregnant women at risk of preterm birth. There is interest in the use of a salivary progesterone test as a screening tool preliminary evidence from India, Egypt and UK has shown promise for this type of test. The test requires further validation in a low resource community setting. METHODS: The Promises study aims to validate and test the feasibility of introducing a low-cost salivary progesterone preterm birth prediction test in two rural districts in India with high rates of prematurity. It is a prospective study of 2000 pregnant women recruited from Panna and Satna in Madhya Pradesh over approximately 24 months. Demographic and pregnancy outcome data will be collected, and pregnancies will be dated by ultrasound sonography. Saliva progesterone will be measured by ELISA in samples obtained between 24-28 weeks of gestation. The association between salivary progesterone and preterm birth will be determined and the utility of salivary progesterone to predict preterm birth < 34, as well as < 30 and < 37 weeks assessed. Additional qualitative data will be obtained in terms of acceptability and feasibility of saliva progesterone testing and knowledge of PTB. DISCUSSION: A validated cost-effective saliva test, which has potential for further adaptation to a 'point of care' setting will allow early identification of pregnant women at risk of preterm birth, who can be linked to an effective pathway of care and support to reduce preterm birth and associated adverse consequences. This will reduce both economic and emotional burden on the affected women and their families.


Asunto(s)
Recién Nacido de Bajo Peso/metabolismo , Nacimiento Prematuro/diagnóstico , Progestinas/metabolismo , Proyectos de Investigación , Saliva/metabolismo , Adulto , Biomarcadores , Estudios de Factibilidad , Femenino , Humanos , India/epidemiología , Recién Nacido , Embarazo , Resultado del Embarazo , Nacimiento Prematuro/epidemiología , Nacimiento Prematuro/metabolismo , Estudios Prospectivos
20.
J Physiol ; 595(6): 2065-2084, 2017 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-28083928

RESUMEN

KEY POINTS: Older pregnant women have a greater risk of operative delivery, still birth and post-term induction. This suggests that maternal age can influence the timing of birth and processes of parturition. We have found that increasing maternal age in C57BL/6J mice is associated with prolongation of gestation and length of labour. Older pregnant mice also had delayed progesterone withdrawal and impaired myometrial function. Uterine ageing and labour dysfunction should be investigated further in older primigravid women. ABSTRACT: Advanced maternal age (≥35 years) is associated with increased rates of operative delivery, stillbirth and post-term labour induction. The physiological causes remain uncertain, although impaired myometrial function has been implicated. To investigate the hypothesis that maternal age directly influences successful parturition, we assessed the timing of birth and fetal outcome in pregnant C57BL/6J mice at 3 months (young) and 5 months (intermediate) vs. 8 months (older) of age using infrared video recording. Serum progesterone profiles, myometrium and cervix function, and mitochondrial electron transport chain complex enzymatic activities were also examined. Older pregnant mice had a longer mean gestation and labour duration (P < 0.001), as well as reduced litter size (P < 0.01) vs. 3-month-old mice. Older mice did not exhibit the same decline in serum progesterone concentrations as younger mice. Cervical tissues from older mice were more distensible than younger mice (P < 0.05). Oxytocin receptor and connexin-43 mRNA expression were reduced in the myometrium from 8-month-old vs. 3-month-old mice (P < 0.05 and P < 0.01 respectively) in tandem with more frequent but shorter duration spontaneous myometrial contractions (P < 0.05) and an attenuated contractile response to oxytocin. Myometrial mitochondrial copy number was reduced in older mice, although there were no age-induced changes to the enzymatic activities of the mitochondrial electron transport chain complexes. In conclusion, 8-month-old mice provide a useful model of reproductive ageing. The present study has identified potential causes of labour dysfunction amenable to investigation in older primigravid women.


Asunto(s)
Envejecimiento/fisiología , Útero/fisiología , Animales , Colágeno/metabolismo , ADN Mitocondrial/genética , Femenino , Metaloproteinasa 2 de la Matriz/metabolismo , Ratones , Ratones Endogámicos C57BL , Oxitócicos/farmacología , Oxitocina/farmacología , Parto/fisiología , Embarazo , Progesterona/sangre , Resistencia a la Tracción , Contracción Uterina/efectos de los fármacos , Útero/anatomía & histología , Útero/efectos de los fármacos , Útero/metabolismo
SELECCIÓN DE REFERENCIAS
Detalles de la búsqueda