Acute Myocardial Infarction in Pregnancy.

Pregnancy-associated myocardial infarction is an overall uncommon event, but can be associated with significant maternal and fetal morbidity and mortality. In contrast to myocardial infarction in the general nonpregnant population, the mechanism of pregnancy-associated myocardial infarction is most commonly due to nonatherosclerotic mechanisms such as coronary dissection, vasospasm, or thromboembolism. The diagnosis of pregnancy-associated myocardial infarction can be challenging, requiring a high index of suspicion for prompt recognition and management. Furthermore, the management of pregnancy-associated myocardial infarction can be complex due to maternal and fetal considerations and may vary based on the specific underlying mechanism of the myocardial infarction. This review aims to review the recent literature on pregnancy-associated myocardial infarction and summarize the epidemiology, mechanisms, diagnosis, and treatment strategies for this uncommon entity.

Maternal cardiovascular adaptation to pregnancy in obese pregnant women.

INTRODUCTION: Obesity is known to be associated with cardiovascular compromise and a major risk factor for the development of hypertensive disorders in pregnancy. However, little is known about the effect of obesity on maternal cardiac function. The aim of this study was to investigate the effect of obesity on the maternal cardiovascular system. MATERIAL AND METHODS: This was a prospective, observational, longitudinal study. Pregnant women with booking body mass index (BMI) ≥30 kg/m2 were compared with pregnant women with normal booking BMI 20-24.9 kg/m2. Participants were seen at three time points during pregnancy; 12-14, 20-24 and 30-32 weeks. At all visits, maternal blood pressure (BP) was measured, and cardiac geometry and function were assessed using two-dimensional trans-thoracic echocardiography. Multilevel linear mixed-effects models were used for all the comparisons. RESULTS: Fifty-nine pregnant women with obesity were compared with 14 pregnant women with normal BMI. In women with obesity, the maternal BP, heart rate and cardiac output were higher and peripheral vascular resistance was lower (p < 0.01 for all comparisons) compared with normal BMI women. Women with obesity had altered cardiac geometry with higher left ventricular end diastolic diameter, intraventricular septal thickness, posterior wall diameter, relative wall thickness and left ventricular mass (p < 0.001 for all comparisons). There was also evidence of impaired diastolic indices in the obese group with a lower E/A ratio, tissue Doppler imaging E' lateral and medial and higher left atrial volume (p < 0.01 for all comparisons). Finally, women with obesity had reduced longitudinal function, as assessed by mitral plane annular systolic excursion, between the second and third trimester of pregnancy, indicating possible early cardiac dysfunction in this group. CONCLUSIONS: Obesity is associated with maternal hyperdynamic circulation, altered cardiac geometry and suboptimal diastolic function, compared with normal BMI pregnant women, and these factors may contribute to the increased risk of complications in obese pregnant women.

Antimicrobial stewardship and targeted therapies in the changing landscape of maternal sepsis.

Pregnant and postnatal women are a high-risk population particularly prone to rapid progression to sepsis with significant morbidity and mortality worldwide. Moreover, severe maternal infections can have a serious detrimental impact on neonates with almost 1 million neonatal deaths annually attributed to maternal infection or sepsis. In this review we discuss the susceptibility of pregnant women and their specific physiological and immunological adaptations that contribute to their vulnerability to sepsis, the implications for the neonate, as well as the issues with antimicrobial stewardship and the challenges this poses when attempting to reach a balance between clinical care and urgent treatment. Finally, we review advancements in the development of pregnancy-specific diagnostic and therapeutic approaches and how these can be used to optimize the care of pregnant women and neonates.

Socio-economic factors determine maternal and neonatal outcomes in women with peripartum cardiomyopathy: A study of the ESC EORP PPCM registry.

BACKGROUND: Peripartum cardiomyopathy (PPCM) is a global disease with substantial morbidity and mortality. The aim of this study was to analyze to what extent socioeconomic factors were associated with maternal and neonatal outcomes. METHODS: In 2011, >100 national and affiliated member cardiac societies of the European Society of Cardiology (ESC) were contacted to contribute to a global PPCM registry, under the auspices of the ESC EORP Programme. We investigated the characteristics and outcomes of women with PPCM and their babies according to individual and country-level sociodemographic factors (Gini index coefficient [GINI index], health expenditure [HE] and human developmental index [HDI]). RESULTS: 739 women from 49 countries (Europe [33%], Africa [29%], Asia-Pacific [15%], Middle East [22%]) were enrolled. Low HDI was associated with greater left ventricular (LV) dilatation at time of diagnosis. However, baseline LV ejection fraction did not differ according to sociodemographic factors. Countries with low HE prescribed guideline-directed heart failure therapy less frequently. Six-month mortality was higher in countries with low HE; and LV non-recovery in those with low HDI, low HE and lower levels of education. Maternal outcome (death, re-hospitalization, or persistent LV dysfunction) was independently associated with income. Neonatal death was significantly more common in countries with low HE and low HDI, but was not influenced by maternal income or education attainment. CONCLUSIONS: Maternal and neonatal outcomes depend on country-specific socioeconomic characteristics. Attempts should therefore be made to allocate adequate resources to health and education, to improve maternal and fetal outcomes in PPCM.

Cardiogenic shock in pregnancy.

Cardiac disease complicates 1%-4% of pregnancies globally, with a predominance in low and middle-income countries (LMICs). Increasing maternal age, rates of obesity, cardiovascular comorbidities, pre-eclampsia and gestational diabetes all contribute to acquired cardiovascular disease in pregnancy. Additionally, improved survival in congenital heart disease (CHD) has led to increasing numbers of women with CHD undergoing pregnancy. Implementation of individualised care plans formulated through pre-conception counselling and based on national and international guidance have contributed to improved clinical outcomes. However, there remains a significant proportion of women of reproductive age with no apparent comorbidities or risk factors that develop heart disease during pregnancy, with no indication for pre-conception counselling. The most extreme manifestation of cardiac disease is cardiogenic shock (CS), where the primary cardiac pathology results in inadequate cardiac output and hypoperfusion, and is associated with significant mortality and morbidity. Key to management is early recognition, intervention to treat any potentially reversible underlying pathology and supportive measures, up to and including mechanical circulatory support (MCS). In this narrative review we discuss recent developments in the classification of CS, and how these may be adapted to improve outcomes of pregnant women with, or at risk of developing, this potentially lethal condition.

Docosahexaenoic Acid Explains the Unexplained in Visual Transduction.

In George Wald's Nobel Prize acceptance speech for "discoveries concerning the primary physiological and chemical visual processes in the eye", he noted that events after the activation of rhodopsin are too slow to explain visual reception. Photoreceptor membrane phosphoglycerides contain near-saturation amounts of the omega-3 fatty acid docosahexaenoic acid (DHA). The visual response to a photon is a retinal cis-trans isomerization. The trans-state is lower in energy; hence, a quantum of energy is released equivalent to the sum of the photon and cis-trans difference. We hypothesize that DHA traps this energy, and the resulting hyperpolarization extracts the energized electron, which depolarizes the membrane and carries a function of the photon's energy (wavelength) to the brain. There, it contributes to the creation of the vivid images of our world that we see in our consciousness. This proposed revision to the visual process provides an explanation for these previously unresolved issues around the speed of information transfer and the purity of conservation of a photon's wavelength and supports observations of the unique and indispensable role of DHA in the visual process.

Pregnancy outcomes in women with Ebstein's anomaly: data from the Registry of Pregnancy And Cardiac disease (ROPAC).

OBJECTIVE: Ebstein's anomaly is a rare congenital cardiac condition and data regarding pregnancy outcomes in this patient group are scarce. We evaluated the maternal and perinatal risks of pregnancy in 81 women with Ebstein's anomaly. METHODS: The Registry of Pregnancy and Cardiac disease is a prospective global registry of pregnancies in women with structural cardiac disease. Pregnancy outcomes in women with Ebstein's anomaly were examined. The primary outcome was the occurrence of a major adverse cardiac event (MACE) defined as maternal mortality, heart failure, arrhythmia, thromboembolic event or endocarditis. Secondary endpoints were obstetric and perinatal outcomes and the influence of pregnancy on tricuspid valve regurgitation as well as right atrial and ventricular dimensions. RESULTS: In the 81 women with Ebstein's anomaly (mean age 29.7±6.1 years, 46.9% nulliparous), MACE occurred in 8 (9.9%) pregnancies, mostly heart failure (n=6). There were no maternal deaths. Prepregnancy signs of heart failure were predictive for MACE. Almost half of the women were delivered by caesarean section (45.7%) and preterm delivery occurred in 24.7%. Neonatal mortality was 2.5% and 4.9% of the infants had congenital heart disease. In the subgroup in which prepregnancy and postpregnancy data were available, there was no difference in tricuspid valve regurgitation grade or right atrial and ventricular dimensions before and after pregnancy. CONCLUSIONS: Most women with Ebstein's anomaly tolerate pregnancy well, but women with prepregnancy signs of heart failure are at higher risk for MACE during pregnancy and should be counselled accordingly.

Pregnancy in women with congenital heart disease: a focus on management and preventing the risk of complications.

INTRODUCTION: Congenital heart disease (CHD) is the most common cardiac disorder in pregnancy in the western world (around 80%). Due to improvements in surgical interventions more women with CHD are surviving to adulthood and choosing to become pregnant. AREAS COVERED: Preconception counseling, antenatal management of CHDs and strategies to prevent maternal and fetal complications.Preconception counseling should start early, before the transition to adult care and be offered to both men and women. It should include the choice of contraception, lifestyle modifications, pre-pregnancy optimization of cardiac state, the chance of the child inheriting a similar cardiac lesion, the risks to the mother, and long-term prognosis. Pregnancy induces marked physiological changes in the cardiovascular system that may precipitate cardiac complications. Risk stratification is based on the underlying cardiac disease and data from studies including CARPREG, ZAHARA, and ROPAC. EXPERT OPINION: Women with left to right shunts, regurgitant lesions, and most corrected CHDs are at lower risk and can be managed in secondary care. Complex CHD, including systemic right ventricle need expert counseling in a tertiary center. Those with severe stenotic lesions, pulmonary artery hypertension, and Eisenmenger's syndrome should avoid pregnancy, be given effective contraception and managed in a tertiary center if pregnancy does happen.

B-type natriuretic peptide in low-risk pregnancy and pregnancy with congenital heart disease.

OBJECTIVE: To perform a longitudinal assessment of B-type natriuretic peptide (BNP) and its association with cardiac function in low-risk pregnant women and in pregnant women with congenital heart disease (CHD). METHODS: Longitudinal study in low-risk pregnancy and pregnancy in women with CHD seen at 10-14, 18-22, and 30-34 weeks of pregnancy for BNP quantification and exercise studies using impedance cardiography (ICG). RESULTS: Forty-three low-risk women with longitudinal samples (129 samples, 43 in each trimester) and 30 pregnant women with CHD with convenience samples (first trimester, five samples; second trimester, 20 samples; third trimester, 21 samples) were included. Women with CHD delivered earlier by 6 days (P = 0.002) and their newborns had lower birth weight independent of gestational age (birth weight centile 30.0 vs 55.0, P = 0.005). In low-risk women, BNP levels were lower in the third trimester (P < 0.001). There were no statistically significant differences in BNP concentrations across trimesters in the CHD group, no differences in BNP concentrations between the two groups, and no significant correlations between BNP concentration in each trimester with cardiac output, stroke volume, or heart rate (at rest/with exercise). CONCLUSION: This study assessed BNP longitudinally in the first, second and third trimesters in singleton low-risk pregnancy, and showed that BNP concentration decreased with advancing gestational age, with no participants with levels greater than 40.0 pg/mL in the third trimester. BNP concentrations were similar in women with and without congenital heart disease. We found no correlation between circulating levels of BNP and maternal hemodynamics at rest or with exercise measured by ICG to support its use as a marker of cardiac function.

Roles of N-linked glycosylation and glycan-binding proteins in placentation: trophoblast infiltration, immunomodulation, angiogenesis, and pathophysiology.

Protein N-linked glycosylation is a structurally diverse post-translational modification that stores biological information in a larger order of magnitude than other post-translational modifications such as phosphorylation, ubiquitination and acetylation. This gives N-glycosylated proteins a diverse range of properties and allows glyco-codes (glycan-related information) to be deciphered by glycan-binding proteins (GBPs). The intervillous space of the placenta is richly populated with membrane-bound and secreted glycoproteins. Evidence exists to suggest that altering the structural nature of their N-glycans can impact several trophoblast functions, which include those related to interactions with decidual cells. This review summarizes trophoblast-related activities influenced by N-glycan-GBP recognition, exploring how different subtypes of trophoblasts actively adapt to characteristics of the decidualized endometrium through cell-specific expression of N-glycosylated proteins, and how these cells receive decidua-derived signals via N-glycan-GBP interactions. We highlight work on how changes in N-glycosylation relates to the success of trophoblast infiltration, interactions of immunomodulators, and uterine angiogenesis. We also discuss studies that suggest aberrant N-glycosylation of trophoblasts may contribute to the pathogenesis of pregnancy complications (e.g. pre-eclampsia, early spontaneous miscarriages and hydatidiform mole). We propose that a more in-depth understanding of how N-glycosylation shapes trophoblast phenotype during early pregnancy has the potential to improve our approach to predicting, diagnosing and alleviating poor maternal/fetal outcomes associated with placental dysfunction.

Percutaneous intervention of severe native coarctation of the aorta presenting in pregnancy: a case report.

Background: Coarctation of the aorta (CoA) is one of the more common congenital heart defects affecting up to 5% of patients with congenital heart disease. Pregnant patients with unrepaired or severe re-coarctation are considered to be modified World Health Organisation (mWHO) IV, have the highest risk of maternal mortality and morbidity. The management of unrepaired CoA during pregnancy is influenced by a variety of factors which include the extent of the coarctation and coarctation characteristics, but due to paucity of data, it largely relies on expert opinion. Case summary: A 27 year old multi-gravid woman underwent successful percutaneous stent implantation for severe native CoA due to maternal resistant hypertension and foetal cardiac compromise on echocardiography. After intervention, the remainder of her pregnancy was uneventful with improved arterial hypertension control. The foetal cardiac structures, namely left ventricular size, improved after intervention. This case demonstrates the importance of CoA intervention during pregnancy to optimise both maternal and foetal outcome. Conclusion: Coarctation of the aorta should be considered in pregnant women with poorly controlled hypertension. This case also highlights that, despite associated risks, percutaneous intervention can lead to improved maternal haemodynamics and fetal growth.

cAMP Compartmentalisation in Human Myometrial Cells.

Preterm birth is the leading cause of childhood mortality and morbidity. A better understanding of the processes that drive the onset of human labour is essential to reduce the adverse perinatal outcomes associated with dysfunctional labour. Beta-mimetics, which activate the myometrial cyclic adenosine monophosphate (cAMP) system, successfully delay preterm labour, suggesting a key role for cAMP in the control of myometrial contractility; however, the mechanisms underpinning this regulation are incompletely understood. Here we used genetically encoded cAMP reporters to investigate cAMP signalling in human myometrial smooth muscle cells at the subcellular level. We found significant differences in the dynamics of the cAMP response in the cytosol and at the plasmalemma upon stimulation with catecholamines or prostaglandins, indicating compartment-specific handling of cAMP signals. Our analysis uncovered significant disparities in the amplitude, kinetics, and regulation of cAMP signals in primary myometrial cells obtained from pregnant donors compared with a myometrial cell line and found marked response variability between donors. We also found that in vitro passaging of primary myometrial cells had a profound impact on cAMP signalling. Our findings highlight the importance of cell model choice and culture conditions when studying cAMP signalling in myometrial cells and we provide new insights into the spatial and temporal dynamics of cAMP in the human myometrium.

The imperative of arachidonic acid in early human development.

This review is about the role of arachidonic acid (ArA) in foetal and early growth and development. In 1975 and '76, we reported the preferential incorporation of ArA into the developing brain of rat pups, its conservation as a principal component in the brains of 32 mammalian species and the high proportion delivered by the human placenta for foetal nutrition, compared to its parent linoleic acid (LA). ArA is quantitatively the principal acyl component of membrane lipids from foetal red cells, mononuclear cells, astrocytes, endothelium, and placenta. Functionally, we present evidence that ArA, but not DHA, relaxes the foetal mesenteric arteries. The placenta biomagnifies ArA, doubling the proportion of the maternal level in cord blood. The proportions of ArA and its allies (di-homo-gamma-linolenic acid (DGLA), adrenic acid and ω6 docosapentaenoic acid) are similar or higher than the total of ω3 fatty acids in human milk, maintaining the abundant supply to the developing infant. Despite the evidence of the importance of ArA, the European Food Standard Agency, in 2014 rejected the joint FAO and WHO recommendation on the inclusion of ArA in infant formula, although they recommended DHA. The almost universal dominance of ArA in the membrane phosphoglycerides during human organogenesis and prenatal growth suggests that the importance of ArA and its allies in reproductive biology needs to be re-evaluated urgently.

Favipiravir in patients hospitalised with COVID-19 (PIONEER trial): a multicentre, open-label, phase 3, randomised controlled trial of early intervention versus standard care.

BACKGROUND: COVID-19 has overwhelmed health services globally. Oral antiviral therapies are licensed worldwide, but indications and efficacy rates vary. We aimed to evaluate the safety and efficacy of oral favipiravir in patients hospitalised with COVID-19. METHODS: We conducted a multicentre, open-label, randomised controlled trial of oral favipiravir in adult patients who were newly admitted to hospital with proven or suspected COVID-19 across five sites in the UK (n=2), Brazil (n=2) and Mexico (n=1). Using a permuted block design, eligible and consenting participants were randomly assigned (1:1) to receive oral favipiravir (1800 mg twice daily for 1 day; 800 mg twice daily for 9 days) plus standard care, or standard care alone. All caregivers and patients were aware of allocation and those analysing data were aware of the treatment groups. The prespecified primary outcome was the time from randomisation to recovery, censored at 28 days, which was assessed using an intention-to-treat approach. Post-hoc analyses were used to assess the efficacy of favipiravir in patients aged younger than 60 years, and in patients aged 60 years and older. The trial was registered with clinicaltrials.gov, NCT04373733. FINDINGS: Between May 5, 2020 and May 26, 2021, we assessed 503 patients for eligibility, of whom 499 were randomly assigned to favipiravir and standard care (n=251) or standard care alone (n=248). There was no significant difference between those who received favipiravir and standard care, relative to those who received standard care alone in time to recovery in the overall study population (hazard ratio [HR] 1·06 [95% CI 0·89-1·27]; n=499; p=0·52). Post-hoc analyses showed a faster rate of recovery in patients younger than 60 years who received favipiravir and standard care versus those who had standard care alone (HR 1·35 [1·06-1·72]; n=247; p=0·01). 36 serious adverse events were observed in 27 (11%) of 251 patients administered favipiravir and standard care, and 33 events were observed in 27 (11%) of 248 patients receiving standard care alone, with infectious, respiratory, and cardiovascular events being the most numerous. There was no significant between-group difference in serious adverse events per patient (p=0·87). INTERPRETATION: Favipiravir does not improve clinical outcomes in all patients admitted to hospital with COVID-19, however, patients younger than 60 years might have a beneficial clinical response. The indiscriminate use of favipiravir globally should be cautioned, and further high-quality studies of antiviral agents, and their potential treatment combinations, are warranted in COVID-19. FUNDING: LifeArc and CW+.

Multifaceted Fontan Patients and Their Response to Pregnancy.

We present 4 patients with Fontan circulation who underwent successful pregnancies, albeit with complications that required close monitoring and timely intervention. Each Fontan patient presents with a unique clinical picture, making risk stratification challenging but all the more important.

Multigenerational diabetes mellitus.

Gestational diabetes (GDM) changes the maternal metabolic and uterine environment, thus increasing the risk of short- and long-term adverse outcomes for both mother and child. Children of mothers who have GDM during their pregnancy are more likely to develop Type 2 Diabetes (T2D), early-onset cardiovascular disease and GDM when they themselves become pregnant, perpetuating a multigenerational increased risk of metabolic disease. The negative effect of GDM is exacerbated by maternal obesity, which induces a greater derangement of fetal adipogenesis and growth. Multiple factors, including genetic, epigenetic and metabolic, which interact with lifestyle factors and the environment, are likely to contribute to the development of GDM. Genetic factors are particularly important, with 30% of women with GDM having at least one parent with T2D. Fetal epigenetic modifications occur in response to maternal GDM, and may mediate both multi- and transgenerational risk. Changes to the maternal metabolome in GDM are primarily related to fatty acid oxidation, inflammation and insulin resistance. These might be effective early biomarkers allowing the identification of women at risk of GDM prior to the development of hyperglycaemia. The impact of the intra-uterine environment on the developing fetus, "developmental programming", has a multisystem effect, but its influence on adipogenesis is particularly important as it will determine baseline insulin sensitivity, and the response to future metabolic challenges. Identifying the critical window of metabolic development and developing effective interventions are key to our ability to improve population metabolic health.

The Cultural and Commercial Value of Tulsi (Ocimum tenuiflorum L.): Multidisciplinary Approaches Focusing on Species Authentication.

Tulsi (Holy basil, Ocimum tenuiflorum L., Lamiaceae), native to Asia, has become globalised as the cultural, cosmetic, and medicinal uses of the herb have been popularised. DNA barcoding, a molecular technique used to identify species based on short regions of DNA, can discriminate between different species and identify contaminants and adulterants. This study aimed to explore the values associated with Tulsi in the United Kingdom (UK) and authenticate samples using DNA barcoding. A mixed methods approach was used, incorporating social research (i.e., structured interviews) and DNA barcoding of Ocimum samples using the ITS and trnH-psbA barcode regions. Interviews revealed the cultural significance of Tulsi: including origins, knowledge exchange, religious connotations, and medicinal uses. With migration, sharing of plants and seeds has been seen as Tulsi plants are widely grown in South Asian (SA) households across the UK. Vouchered Ocimum specimens (n = 33) were obtained to create reference DNA barcodes which were not available in databases. A potential species substitution of O. gratissimum instead of O. tenuiflorum amongst SA participants was uncovered. Commercial samples (n = 47) were difficult to authenticate, potentially due to DNA degradation during manufacturing processes. This study highlights the cultural significance of Tulsi, despite a potential species substitution, the plant holds a prestigious place amongst SA families in the UK. DNA barcoding was a reliable way to authenticate Ocimum species.

Safety of beta-blocker and calcium channel blocker antihypertensive drugs in pregnancy: a Mendelian randomization study.

BACKGROUND: Beta-blocker (BB) and calcium channel blocker (CCB) antihypertensive drugs are commonly used in pregnancy. However, data on their relative impact on maternal and foetal outcomes are limited. We leveraged genetic variants mimicking BB and CCB antihypertensive drugs to investigate their effects on risk of pre-eclampsia, gestational diabetes and birthweight using the Mendelian randomization paradigm. METHODS: Genetic association estimates for systolic blood pressure (SBP) were extracted from summary data of a genome-wide association study (GWAS) on 757,601 participants. Uncorrelated single-nucleotide polymorphisms (SNPs) associated with SBP (p < 5 × 10-8) in BB and CCB drug target gene regions were selected as proxies for drug target perturbation. Genetic association estimates for the outcomes were extracted from GWASs on 4743 cases and 136,325 controls (women without a hypertensive disorder in pregnancy) for pre-eclampsia or eclampsia, 7676 cases and 130,424 controls (women without any pregnancy-related morbidity) for gestational diabetes, and 155,202 women (who have given birth at least once) for birthweight of the first child. All studies were in European ancestry populations. Mendelian randomization estimates were generated using the two-sample inverse-variance weighted model. RESULTS: Although not reaching the conventional threshold for statistical significance, genetically-proxied BB was associated with reduced risk of pre-eclampsia (OR per 10 mmHg SBP reduction 0.27, 95%CI 0.06-1.19, p = 0.08) and increased risk of gestational diabetes (OR per 10 mmHg SBP reduction 2.01, 95%CI 0.91-4.42, p = 0.08), and significantly associated with lower birthweight of first child (beta per 10 mmHg SBP reduction - 0.27, 95%CI - 0.39 to - 0.15, p = 1.90 × 10-5). Genetically-proxied CCB was associated with reduced risk of pre-eclampsia and eclampsia (OR 0.62, 95%CI 0.43-0.89, p = 9.33 × 10-3), and was not associated with gestational diabetes (OR 1.05, 95% CI 0.76-1.45, p = 0.76) or changes in birthweight of first child (beta per 10 mmHg SBP reduction 0.02, 95%CI - 0.04-0.07, p = 0.54). CONCLUSIONS: While BB and CCB antihypertensive drugs may both be efficacious for lowering blood pressure in pregnancy, this genetic evidence suggests that BB use may lower birthweight. Conversely, CCB use may reduce risk of pre-eclampsia and eclampsia without impacting gestational diabetes risk or birthweight. These data support further study on the effects of BBs on birthweight.

Dynamic Changes in Uterine NK Cell Subset Frequency and Function Over the Menstrual Cycle and Pregnancy.

Uterine natural killer cells (uNK) play an important role in promoting successful pregnancy by regulating trophoblast invasion and spiral artery remodelling in the first trimester. Recently, single-cell RNA sequencing (scRNAseq) on first-trimester decidua showed that uNK can be divided into three subsets, which may have different roles in pregnancy. Here we present an integration of previously published scRNAseq datasets, together with novel flow cytometry data to interrogate the frequency, phenotype, and function of uNK1-3 in seven stages of the reproductive cycle (menstrual, proliferative, secretory phases of the menstrual cycle; first, second, and third trimester; and postpartum). We found that uNK1 and uNK2 peak in the first trimester, but by the third trimester, the majority of uNK are uNK3. All three subsets are most able to degranulate and produce cytokines during the secretory phase of the menstrual cycle and express KIR2D molecules, which allow them to interact with HLA-C expressed by placental extravillous trophoblast cells, at the highest frequency during the first trimester. Taken together, our findings suggest that uNK are particularly active and able to interact with placental cells at the time of implantation and that uNK1 and uNK2 may be particularly involved in these processes. Our findings are the first to establish how uNK frequency and function change dynamically across the healthy reproductive cycle. This serves as a platform from which the relationship between uNK function and impaired implantation and placentation can be investigated. This will have important implications for the study of subfertility, recurrent miscarriage, pre-eclampsia, and pre-term labour.