Reduced gyrification in fetal growth restriction with prenatal magnetic resonance images.

Placental-related fetal growth restriction, resulting from placental dysfunction, impacts 3-5% of pregnancies and is linked to elevated risk of adverse neurodevelopmental outcomes. In response, the fetus employs a mechanism known as brain-sparing, redirecting blood flow to the cerebral circuit, for adequate supply to the brain. In this study we aimed to quantitatively evaluate disparities in gyrification and brain volumes among fetal growth restriction, small for gestational age and appropriate-for gestational-age fetuses. Additionally, we compared fetal growth restriction fetuses with and without brain-sparing. The study encompassed 106 fetuses: 35 fetal growth restriction (14 with and 21 without brain-sparing), 8 small for gestational age, and 63 appropriate for gestational age. Gyrification, supratentorial, and infratentorial brain volumes were automatically computed from T2-weighted magnetic resonance images, following semi-automatic brain segmentation. Fetal growth restriction fetuses exhibited significantly reduced gyrification and brain volumes compared to appropriate for gestational age (P < 0.001). Small for gestational age fetuses displayed significantly reduced gyrification (P = 0.038) and smaller supratentorial volume (P < 0.001) compared to appropriate for gestational age. Moreover, fetal growth restriction fetuses with BS demonstrated reduced gyrification compared to those without BS (P = 0.04), with no significant differences observed in brain volumes. These findings demonstrate that brain development is affected in fetuses with fetal growth restriction, more severely than in small for gestational age, and support the concept that vasodilatation of the fetal middle cerebral artery reflects more severe hypoxemia, affecting brain development.

Brain Metabolite Differences in Fetuses With Cytomegalovirus Infection: A Magnetic Resonance Spectroscopy Study.

BACKGROUND: Cytomegalovirus (CMV) is the most common intrauterine infection and may be associated with unfavorable outcomes. While some CMV-infected fetuses may show gross or subtle brain abnormalities on MRI, their clinical significance may be unclear. Conversely, normal development cannot be guaranteed in CMV-infected fetuses with normal MRI. PURPOSE: To assess brain metabolite differences in CMV-infected fetuses using magnetic resonance spectroscopy (MRS). STUDY TYPE: Retrospective. SUBJECTS: Out of a cohort of 149 cases, 44 with maternal CMV infection, amniocentesis results, and good-quality MRS were included. CMV-infected fetuses with positive polymerase chain reaction (PCR) (N = 35) were divided based on MRI results as follows: typical brain abnormalities (gross findings, N = 8), exclusive white matter hyperintense signal (WMHS) on T2-weighted images (subtle findings, N = 7), and normal MRI (N = 20). Uninfected fetuses (negative PCR) with normal MRI were included as controls (N = 9). FIELD STRENGTH: 3 T, T2-weighted half Fourier single-shot turbo spin-echo (HASTE), T2-weighted true fast imaging with steady-state free precession (TrueFISP), T1- and T2*-weighted fast low angle shot (FLASH), and 1H-MRS single-voxel point resolved spectroscopy (PRESS) sequences. ASSESSMENT: MRI findings were assessed by three radiologists, and metabolic ratios within the basal ganglia were calculated using LCModel. STATISTICAL TESTS: Analysis of covariance test with Bonferroni correction for multiple comparisons was used to compare metabolic ratios between groups while accounting for gestational age. A P-value <0.05 was deemed significant. RESULTS: MRS was successfully acquired in 63% of fetuses. Substantial agreement was observed between radiologists (Fleiss' kappa [k] = 0.8). Infected fetuses with gross MRI findings exhibited significantly reduced tNAA/tCr ratios (0.64 ± 0.08) compared with infected fetuses with subtle MRI findings (0.85 ± 0.19), infected fetuses with normal MRI (0.8 ± 0.14) and controls (0.81 ± 0.15). No other significant differences were detected (P ≥ 0.261). CONCLUSION: Reduced tNAA/tCr within the apparently normal brain tissue was detected in CMV-infected fetuses with gross brain abnormalities, suggesting extensive brain damage. In CMV-infected fetuses with isolated WMHS, no damage was detected by MRS. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 3.

Gestational diabetes in twin pregnancies-a pathology requiring treatment or a benign physiological adaptation?

There is level-1 evidence that screening for and treating gestational diabetes in singleton pregnancies reduce maternal and neonatal morbidity. However, similar data for gestational diabetes in twin pregnancies are currently lacking. Consequently, the current approach for the diagnosis and management of gestational diabetes in twin pregnancies is based on the same diagnostic criteria and glycemic targets used in singleton pregnancies. However, twin pregnancies have unique physiological characteristics, and many of the typical gestational diabetes-related complications are less relevant for twin pregnancies. These differences raise the question of whether the greater increase in insulin resistance observed in twin pregnancies (which is often diagnosed as diet-treated gestational diabetes) should be considered physiological and potentially beneficial in which case alternative criteria should be used for the diagnosis of gestational diabetes in twin pregnancies. In this review, we summarize the most up-to-date evidence on the epidemiology, pathophysiology, and clinical consequences of gestational diabetes in twin pregnancies and review the available data on twin-specific screening and diagnostic criteria for gestational diabetes. Although twin pregnancies are associated with a higher incidence of diet-treated gestational diabetes, diet-treated gestational diabetes in twin pregnancies is less likely to be associated with adverse outcomes and accelerated fetal growth than in singleton pregnancies and may reduce the risk for intrauterine growth restriction. In addition, there is currently no evidence that treatment of diet-treated gestational diabetes in twin pregnancies improves outcomes, whereas preliminary data suggest that strict glycemic control in such cases might increase the risk for intrauterine growth restriction. Overall, these findings provide support to the hypothesis that the greater transient increase in insulin resistance observed in twin pregnancies is merely a physiological exaggeration of the normal increase in insulin resistance observed in singleton pregnancies (that is meant to support 2 fetuses) rather than a pathology that requires treatment. These data illustrate the need to develop twin-specific screening and diagnostic criteria for gestational diabetes to avoid overdiagnosis of gestational diabetes and to reduce the risks associated with overtreatment of diet-treated gestational diabetes in twin pregnancies. Although data on twin-specific screening and diagnostic criteria are presently scarce, preliminary data suggest that the optimal screening and diagnostic criteria in twin pregnancies are higher than those currently used in singleton pregnancies.

Deep learning-based segmentation of whole-body fetal MRI and fetal weight estimation: assessing performance, repeatability, and reproducibility.

OBJECTIVES: To develop a deep-learning method for whole-body fetal segmentation based on MRI; to assess the method's repeatability, reproducibility, and accuracy; to create an MRI-based normal fetal weight growth chart; and to assess the sensitivity to detect fetuses with growth restriction (FGR). METHODS: Retrospective data of 348 fetuses with gestational age (GA) of 19-39 weeks were included: 249 normal appropriate for GA (AGA), 19 FGR, and 80 Other (having various imaging abnormalities). A fetal whole-body segmentation model with a quality estimation module was developed and evaluated in 169 cases. The method was evaluated for its repeatability (repeated scans within the same scanner, n = 22), reproducibility (different scanners, n = 6), and accuracy (compared with birth weight, n = 7). A normal MRI-based growth chart was derived. RESULTS: The method achieved a Dice = 0.973, absolute volume difference ratio (VDR) = 1.8% and VDR mean difference = 0.75% ([Formula: see text]: - 3.95%, 5.46), and high agreement with the gold standard. The method achieved a repeatability coefficient = 4.01%, ICC = 0.99, high reproducibility with a mean difference = 2.21% ([Formula: see text]: - 1.92%, 6.35%), and high accuracy with a mean difference between estimated fetal weight (EFW) and birth weight of - 0.39% ([Formula: see text]: - 8.23%, 7.45%). A normal growth chart (n = 246) was consistent with four ultrasound charts. EFW based on MRI correctly predicted birth-weight percentiles for all 18 fetuses ≤ 10thpercentile and for 14 out of 17 FGR fetuses below the 3rd percentile. Six fetuses referred to MRI as AGA were found to be < 3rd percentile. CONCLUSIONS: The proposed method for automatic MRI-based EFW demonstrated high performance and sensitivity to identify FGR fetuses. CLINICAL RELEVANCE STATEMENT: Results from this study support the use of the automatic fetal weight estimation method based on MRI for the assessment of fetal development and to detect fetuses at risk for growth restriction. KEY POINTS: • An AI-based segmentation method with a quality assessment module for fetal weight estimation based on MRI was developed, achieving high repeatability, reproducibility, and accuracy. • An MRI-based fetal weight growth chart constructed from a large cohort of normal and appropriate gestational-age fetuses is proposed. • The method showed a high sensitivity for the diagnosis of small fetuses suspected of growth restriction.

Risk factors for relaparotomy after a cesarean delivery: a case-control study.

BACKGROUND: Relaparotomy following a cesarean delivery (CD) is an infrequent complication, with inconsistency regarding risk factors and indications for its occurrence. We therefore aimed to determine risk factors and indications for a relaparotomy following a CD at a single large tertiary center. METHODS: A retrospective case-control single-center study (2013-2023). We identified all women who had a relaparotomy up to six weeks following a CD (study group). Maternal characteristics, obstetrical and surgical data were compared to a control group in a 1:2 ratio. Controls were women with a CD before and immediately after each case in the study group, who did not undergo a relaparotomy. Included were CDs occurring after 24 gestational weeks. CD performed at different centers and indications for repeat surgery unrelated to the primary surgery (e.g., appendicitis) were excluded. Logistic regression was used to adjust for potential confounders. RESULTS: During the study period, 131,268 women delivered at our institution. Of them, 28,280 (21.5%) had a CD, and 130 patients (0.46%) underwent a relaparotomy. Relaparotomies following a CD occurred during the first 24 h, the first week, and beyond the first week, in 59.2%, 33.1%, and 7.7% of cases, respectively. In the multivariable logistic regression analysis, relaparotomy was significantly associated with Mullerian anomalies (aOR 3.33, 95%CI 1.08-10.24, p = 0.036); uterine fibroids (aOR 3.17, 95%CI 1.11-9.05,p = 0.031); multiple pregnancy (aOR 4.1, 95%CI 1.43-11.79,p = 0.009); hypertensive disorders of pregnancy (aOR 3.46, 95%CI 1.29-9.3,p = 0.014); CD during the second stage of labor (aOR 2.54, 95%CI 1.15-5.88, p = 0.029); complications during CD (aOR 1.62, 95%CI 1.09-3.21,p = 0.045); and excessive bleeding during CD or implementation of bleeding control measures (use of tranexamic acid, a hemostatic agent, or a surgical drain) (aOR 2.23, 95%CI 1.29-4.12,p = 0.012). Indications for relaparotomy differed depending on the time elapsed from the CD, with suspected intra-abdominal bleeding (36.1%) emerging as the primary indication within the initial 24 h. CONCLUSION: We detected several pregnancy, intrapartum, and intra-operative risk factors for the need for relaparotomy following a CD. Practitioners may utilize these findings to proactively identify women at risk, thereby potentially reducing their associated morbidity.

Risk factors for maternal complications following uterine rupture: a 12-year single-center experience.

PURPOSE: To determine maternal outcomes and risk factors for composite maternal morbidity following uterine rupture during pregnancy. METHODS: A retrospective cohort study including all women diagnosed with uterine rupture during pregnancy, between 2011 and 2023, at a single-center. Patients with partial uterine rupture or dehiscence were excluded. We compared women who had composite maternal morbidity following uterine rupture to those without. Composite maternal morbidity was defined as any of the following: maternal death; hysterectomy; severe postpartum hemorrhage; disseminated intravascular coagulation; injury to adjacent organs; admission to the intensive care unit; or the need for relaparotomy. The primary outcome was risk factors associated with composite maternal morbidity following uterine rupture. The secondary outcome was the incidence of maternal and neonatal complications following uterine rupture. RESULTS: During the study period, 147,037 women delivered. Of them, 120 were diagnosed with uterine rupture. Among these, 44 (36.7%) had composite maternal morbidity. There were no cases of maternal death and two cases of neonatal death (1.7%); packed cell transfusion was the major contributor to maternal morbidity [occurring in 36 patients (30%)]. Patients with composite maternal morbidity, compared to those without, were characterized by: increased maternal age (34.7 vs. 32.8 years, p = 0.03); lower gestational age at delivery (35 + 5 vs. 38 + 1 weeks, p = 0.01); a higher rate of unscarred uteri (22.7% vs. 2.6%, p < 0.01); and rupture occurring outside the lower uterine segment (52.3% vs. 10.5%, p < 0.01). CONCLUSION: Uterine rupture entails increased risk for several adverse maternal outcomes, though possibly more favorable than previously described. Numerous risk factors for composite maternal morbidity following rupture exist and should be carefully assessed in these patients.

Fetal MRI-Based Body and Adiposity Quantification for Small for Gestational Age Perinatal Risk Stratification.

BACKGROUND: Small for gestational age (SGA) fetuses are at risk for perinatal adverse outcomes. Fetal body composition reflects the fetal nutrition status and hold promise as potential prognostic indicator. MRI quantification of fetal anthropometrics may enhance SGA risk stratification. HYPOTHESIS: Smaller, leaner fetuses are malnourished and will experience unfavorable outcomes. STUDY TYPE: Prospective. POPULATION: 40 SGA fetuses, 26 (61.9%) females: 10/40 (25%) had obstetric interventions due to non-reassuring fetal status (NRFS), and 17/40 (42.5%) experienced adverse neonatal events (CANO). Participants underwent MRI between gestational ages 30 + 2 and 37 + 2. FIELD STRENGTH/SEQUENCE: 3-T, True Fast Imaging with Steady State Free Precession (TruFISP) and T1 -weighted two-point Dixon (T1 W Dixon) sequences. ASSESSMENT: Total body volume (TBV), fat signal fraction (FSF), and the fat-to-body volumes ratio (FBVR) were extracted from TruFISP and T1 W Dixon images, and computed from automatic fetal body and subcutaneous fat segmentations by deep learning. Subjects were followed until hospital discharge, and obstetric interventions and neonatal adverse events were recorded. STATISTICAL TESTS: Univariate and multivariate logistic regressions for the association between TBV, FBVR, and FSF and interventions for NRFS and CANO. Fisher's exact test was used to measure the association between sonographic FGR criteria and perinatal outcomes. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated. A P-value <0.05 was considered statistically significant. RESULTS: FBVR (odds ratio [OR] 0.39, 95% confidence interval [CI] 0.2-0.76) and FSF (OR 0.95, CI 0.91-0.99) were linked with NRFS interventions. Furthermore, TBV (OR 0.69, CI 0.56-0.86) and FSF (OR 0.96, CI 0.93-0.99) were linked to CANO. The FBVR sensitivity/specificity for obstetric interventions was 85.7%/87.5%, and the TBV sensitivity/specificity for CANO was 82.35%/86.4%. The sonographic criteria sensitivity/specificity for obstetric interventions was 100%/33.3% and insignificant for CANO (P = 0.145). DATA CONCLUSION: Reduced TBV and FBVR may be associated with higher rates of obstetric interventions for NRFS and CANO. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 5.

Glycemic control and neonatal outcomes in twin pregnancies with gestational diabetes mellitus.

BACKGROUND: Preliminary data suggest that strict glycemic control in twin pregnancies with gestational diabetes mellitus may not improve outcomes but might increase the risk of fetal growth restriction. OBJECTIVE: This study aimed to investigate the association of maternal glycemic control with the risk of gestational diabetes mellitus-related complications and small for gestational age in twin pregnancies complicated by gestational diabetes mellitus. STUDY DESIGN: This was a retrospective cohort study of all patients with a twin pregnancy complicated by gestational diabetes mellitus in a single tertiary center between 2011 and 2020, and a matched control group of patients with a twin pregnancy without gestational diabetes mellitus in a 1:3 ratio. The exposure was the level of glycemic control, described as the proportion of fasting, postprandial, and overall glucose values within target. Good glycemic control was defined as a proportion of values within target above the 50th percentile. The first coprimary outcome was a composite variable of neonatal morbidity, defined as at least 1 of the following: birthweight >90th centile for gestational age, hypoglycemia requiring treatment, jaundice requiring phototherapy, birth trauma, or admission to the neonatal intensive care unit at term. A second coprimary outcome was small for gestational age, defined as birthweight <10th centile or <3rd centile for gestational age. Associations between the level of glycemic control and the study outcomes were estimated using logistic regression analysis and were expressed as adjusted odds ratio with 95% confidence interval. RESULTS: A total of 105 patients with gestational diabetes mellitus in a twin pregnancy met the study criteria. The overall rate of the primary outcome was 32.4% (34/105), and the overall proportion of pregnancies with a small for gestational age newborn at birth was 43.8% (46/105). Good glycemic control was not associated with a reduction in the risk of composite neonatal morbidity when compared with suboptimal glycemic control (32.1% vs 32.7%; adjusted odds ratio, 2.06 [95% confidence interval, 0.77-5.49]). However, good glycemic control was associated with higher odds of small for gestational age compared with nongestational diabetes mellitus pregnancies, especially in the subgroup of diet-treated gestational diabetes mellitus (65.5% vs 34.0%, respectively; adjusted odds ratio, 4.17 [95% confidence interval, 1.74-10.01] for small for gestational age <10th centile; and 24.1% vs 7.0%, respectively; adjusted odds ratio, 3.97 [95% confidence interval, 1.42-11.10] for small for gestational age <3rd centile). In contrast, the rate of small for gestational age in gestational diabetes mellitus pregnancies with suboptimal control was not considerably different when compared with non-gestational diabetes mellitus pregnancies. In addition, in cases of diet-treated gestational diabetes mellitus, good glycemic control was associated with a left-shift of the distribution of birthweight centiles, whereas the distribution of birthweight centiles among gestational diabetes mellitus pregnancies with suboptimal control was similar to that of nongestational diabetes mellitus pregnancies. CONCLUSION: In patients with gestational diabetes mellitus in a twin pregnancy, good glycemic control is not associated with a reduction in the risk of gestational diabetes mellitus-related complications but may increase the risk of a small for gestational age newborn in the subgroup of patients with mild (diet-treated) gestational diabetes mellitus. These findings further question whether the gestational diabetes mellitus glycemic targets used in singleton pregnancies also apply to twin pregnancies and support the concern that applying the same diagnostic criteria and glycemic targets in twin pregnancies may result in overdiagnosis and overtreatment of gestational diabetes mellitus and potential neonatal harm.

National and international guidelines on the management of twin pregnancies: a comparative review.

Twin gestations are associated with increased risk of pregnancy complications. However, high-quality evidence regarding the management of twin pregnancies is limited, often resulting in inconsistencies in the recommendations of various national and international professional societies. In addition, some recommendations related to the management of twin gestations are often missing from the clinical guidelines dedicated to twin pregnancies and are instead included in the practice guidelines on specific pregnancy complications (eg, preterm birth) of the same professional society. This can make it challenging for care providers to easily identify and compare recommendations for the management of twin pregnancies. This study aimed to identify, summarize, and compare the recommendations of selected professional societies from high-income countries on the management of twin pregnancies, highlighting areas of both consensus and controversy. We reviewed clinical practice guidelines of selected major professional societies that were either specific to twin pregnancies or were focused on pregnancy complications or aspects of antenatal care that may be relevant for twin pregnancies. We decided a priori to include clinical guidelines from 7 high-income countries (United States, Canada, United Kingdom, France, Germany, and Australia and New Zealand grouped together) and from 2 international societies (International Society of Ultrasound in Obstetrics and Gynecology and the International Federation of Gynecology and Obstetrics). We identified recommendations regarding the following care areas: first-trimester care, antenatal surveillance, preterm birth and other pregnancy complications (preeclampsia, fetal growth restriction, and gestational diabetes mellitus), and timing and mode of delivery. We identified 28 guidelines published by 11 professional societies from the 7 countries and 2 international societies. Thirteen of these guidelines focus on twin pregnancies, whereas the other 16 focus on specific pregnancy complications predominantly in singletons but also include some recommendations for twin pregnancies. Most of the guidelines are recent, with 15 of the 29 guidelines published over the past 3 years. We identified considerable disagreement among guidelines, primarily in 4 key areas: screening and prevention of preterm birth, using aspirin to prevent preeclampsia, defining fetal growth restriction, and the timing of delivery. In addition, there is limited guidance on several important areas, including the implications of the "vanishing twin" phenomenon, technical aspects and risks of invasive procedures, nutrition and weight gain, physical and sexual activity, the optimal growth chart to be used in twin pregnancies, the diagnosis and management of gestational diabetes mellitus, and intrapartum care.This consolidation of key recommendations across several clinical practice guidelines can assist healthcare providers in accessing and comparing recommendations on the management of twin pregnancies and identifies high-priority areas for future research based on either continued disagreement among societies or limited current evidence to guide care.

Reduced adipose tissue in growth-restricted fetuses using quantitative analysis of magnetic resonance images.

OBJECTIVES: Fat-water MRI can be used to quantify tissues' lipid content. We aimed to quantify fetal third trimester normal whole-body subcutaneous lipid deposition and explore differences between appropriate for gestational age (AGA), fetal growth restriction (FGR), and small for gestational age fetuses (SGAs). METHODS: We prospectively recruited women with FGR and SGA-complicated pregnancies and retrospectively recruited the AGA cohort (sonographic estimated fetal weight [EFW] ≥ 10th centile). FGR was defined using the accepted Delphi criteria, and fetuses with an EFW < 10th centile that did not meet the Delphi criteria were defined as SGA. Fat-water and anatomical images were acquired in 3 T MRI scanners. The entire fetal subcutaneous fat was semi-automatically segmented. Three adiposity parameters were calculated: fat signal fraction (FSF) and two novel parameters, i.e., fat-to-body volume ratio (FBVR) and estimated total lipid content (ETLC = FSF*FBVR). Normal lipid deposition with gestation and differences between groups were assessed. RESULTS: Thirty-seven AGA, 18 FGR, and 9 SGA pregnancies were included. All three adiposity parameters increased between 30 and 39 weeks (p < 0.001). All three adiposity parameters were significantly lower in FGR compared with AGA (p ≤ 0.001). Only ETLC and FSF were significantly lower in SGA compared with AGA using regression analysis (p = 0.018-0.036, respectively). Compared with SGA, FGR had a significantly lower FBVR (p = 0.011) with no significant differences in FSF and ETLC (p ≥ 0.053). CONCLUSIONS: Whole-body subcutaneous lipid accretion increased throughout the third trimester. Reduced lipid deposition is predominant in FGR and may be used to differentiate FGR from SGA, assess FGR severity, and study other malnourishment pathologies. CLINICAL RELEVANCE STATEMENT: Fetuses with growth restriction have reduced lipid deposition than appropriately developing fetuses measured using MRI. Reduced fat accretion is linked with worse outcomes and may be used for growth restriction risk stratification. KEY POINTS: • Fat-water MRI can be used to assess the fetal nutritional status quantitatively. • Lipid deposition increased throughout the third trimester in AGA fetuses. • FGR and SGA have reduced lipid deposition compared with AGA fetuses, more predominant in FGR.

Should twin-specific growth charts be used to assess fetal growth in twin pregnancies?

One of the hallmarks of twin pregnancies is the slower rate of fetal growth when compared with singleton pregnancies during the third trimester. The mechanisms underlying this phenomenon and whether it represents pathology or benign physiological adaptation are currently unclear. One important implication of these questions relates to the type growth charts that should be used by care providers to monitor growth of twin fetuses. If the slower growth represents pathology (ie, intrauterine growth restriction caused uteroplacental insufficiency), it would be preferable to use a singleton growth chart to identify a small twin fetus that is at risk for perinatal mortality and morbidity. If, however, the relative smallness of twins is the result of benign adaptive mechanisms, it is likely preferable to use a twin-based charts to avoid overdiagnosis of intrauterine growth restriction in twin pregnancies. In the current review, we addressed this question by describing the differences in fetal growth between twin and singleton pregnancies, reviewing the current knowledge regarding the mechanisms responsible for slower fetal growth in twins, summarizing available empirical evidence on the diagnostic accuracy of the 2 types of charts for intrauterine growth restriction in twin pregnancies, and addressing the question of whether uncomplicated dichorionic twins are at an increased risk for fetal death when compared with singleton fetuses. We identified a growing body of evidence that shows that the use of twin charts can reduce the proportion of twin fetuses identified with suspected intrauterine growth restriction by up to 8-fold and can lead to a diagnosis of intrauterine growth restriction that is more strongly associated with adverse perinatal outcomes and hypertensive disorders than a diagnosis of intrauterine growth restriction based on a singleton-based chart without compromising the detection of twin fetuses at risk for adverse outcomes caused by uteroplacental insufficiency. We further found that small for gestational age twins are less likely to experience adverse perinatal outcomes or to have evidence of uteroplacental insufficiency than small for gestational age singletons and that recent data question the longstanding view that uncomplicated dichorionic twins are at an increased risk for fetal death caused by placental insufficiency. Overall, it seems that, based on existing evidence, the of use twin charts is reasonable and may be preferred over the use of singleton charts when monitoring the growth of twin fetuses. Still, it is important to note that the available data have considerable limitations and are primarily derived from observational studies. Therefore, adequately-powered trials are likely needed to confirm the benefit of twin charts before their use is adopted by professional societies.

The association between fetal head station at the first diagnosis of the second stage of labor and delivery outcomes.

BACKGROUND: Controversy surrounds the impact of the fetal head station on labor duration and mode of delivery. Although an extensive body of evidence has been published evaluating fetal head station in early labor, there is a paucity of data on the impact of fetal head descent during the second stage. OBJECTIVE: This study aimed to explore the association between fetal head station at the diagnosis of the second stage of labor and the second stage duration and the risk of operative delivery. STUDY DESIGN: This is a retrospective cohort study of all singleton vertex deliveries in a single tertiary center (2011-2016). Women were grouped according to fetal head station upon the diagnosis of the second stage of labor as follows: above (S<0), at the level (S=0), and below (S>0) the level of the ischial spine. The duration of the second stage and the risk of operative delivery were compared between the groups and stratified by parity. RESULTS: Overall, 34,334 women met the inclusion criteria. Of these, 18,743 (54.6%) were nulliparous and 15,591 (45.4%) were multiparous. Of the nulliparous women, 8.1%, 35.8%, and 56.1% were diagnosed as having fetal head above, at the level, and below the ischial spine upon second stage diagnosis. Of the multiparous women, 19.7%, 35.6%, and 44.7% were diagnosed as having fetal head above, at the level, and below the ischial spine. Fetal head station upon second stage diagnosis was independently and significantly associated with second stage duration (P<.001); however, its contribution was 4.5-fold among nulliparous women compared with multiparous women. In multivariable analysis, after controlling for maternal age, gestational age at delivery, prepregnancy body mass index, epidural anesthesia, and birthweight, the risk of operative delivery was substantially increased in a dose-dependent pattern for both nulliparous and multiparous women. CONCLUSION: The fetal head station at the first diagnosis of the second stage is significantly and independently associated with the duration of the second stage and correlated with the risk of operative delivery in both nulliparous and multiparous women (P<.001).

Gestational diabetes and fetal growth in twin compared with singleton pregnancies.

BACKGROUND: Gestational diabetes mellitus is associated with accelerated fetal growth in singleton pregnancies but may affect twin pregnancies differently because of the slower growth of twin fetuses during the third trimester of pregnancy and their greater predisposition to fetal growth restriction. OBJECTIVE: This study aimed to evaluate the association of gestational diabetes mellitus with longitudinal fetal growth in twin pregnancies and to compare this association with that observed in singleton pregnancies. STUDY DESIGN: This was a retrospective cohort study of all women with a singleton or twin pregnancy who were followed up at a single tertiary referral center between January 2011 and April 2020. Data on estimated fetal weight and individual fetal biometric indices were extracted from ultrasound examinations of eligible women. Generalized linear models were used to model and compare the change in fetal weight and individual biometric indices as a function of gestational age between women with and without gestational diabetes mellitus in twin pregnancies and between women with and without gestational diabetes mellitus in singleton pregnancies. The primary outcome was estimated fetal weight as a function of gestational age. The secondary outcomes were longitudinal growth of individual fetal biometric indices and the rate of small for gestational age and large for gestational age at birth. RESULTS: A total of 26,651 women (94,437 ultrasound examinations) were included in the analysis: 1881 with a twin pregnancy and 24,770 with a singleton pregnancy. The rate of gestational diabetes mellitus in the twin and singleton groups was 9.6% (n=180) and 7.6% (n=1893), respectively. The estimated fetal weight in singleton pregnancies with gestational diabetes mellitus was significantly higher than that in pregnancies without gestational diabetes mellitus (P<.001) starting at approximately 30 weeks of gestation. The differences remained similar after adjusting for maternal age, chronic hypertension, nulliparity, and neonatal sex (P<.001). In twin pregnancies, fetal growth was similar between pregnancies with and without gestational diabetes mellitus (P=.105 and P=.483 for unadjusted and adjusted models, respectively). The findings were similar to the association of gestational diabetes mellitus with the risk of large for gestational fetuses and the growth of each biometric index. When stratified by type of gestational diabetes mellitus treatment, twin pregnancies with gestational diabetes mellitus was associated with accelerated fetal growth only in the subgroup of women with medically treated gestational diabetes mellitus (P<.001), which represented 12% (n=21) of the twin pregnancy group with gestational diabetes mellitus. CONCLUSION: In contrast to singleton pregnancies, twin pregnancies with gestational diabetes mellitus is less likely to be associated with accelerated fetal growth. This finding has raised the question of whether the diagnostic criteria for gestational diabetes mellitus and the blood glucose targets in women diagnosed with gestational diabetes mellitus should be individualized for twin pregnancies.

Patterns of discordant growth and adverse neonatal outcomes in twins.

BACKGROUND: Intertwin size discordance is an independent risk factor for adverse neonatal outcomes in twin pregnancies. However, size discordance at a given point in gestation fails to take into consideration information, such as the timing of onset and the rate of progression of discordance, that may be of prognostic value. OBJECTIVE: In this study, we aimed to identify distinct patterns of discordant fetal growth in twin pregnancies and to determine whether these patterns are predictive of adverse pregnancy outcomes. STUDY DESIGN: This was a retrospective cohort study of women with twin pregnancies in a single tertiary referral center between January 2011 and April 2020, who had at least 3 ultrasound examinations during pregnancy that included assessment of fetal biometry. Size discordance was calculated at each ultrasound examination, and pregnancies were classified into 1 of 4 predetermined patterns based on the timing of onset and the progression of discordance: pattern 1, no significant discordance group (referent); pattern 2, early (<24 weeks' gestation) progressive discordance group; pattern 3, early discordance with plateau group; or pattern 4, late (≥24 weeks' gestation) discordance group. The associations of discordance pattern (using pattern 1 as referent) with preterm birth, preeclampsia, size discordance at birth, and birthweight<10th percentile were expressed as adjusted relative risk with 95% confidence intervals and were compared with those observed for a single measurement of size discordance at 32 weeks' gestation. RESULTS: Of 2075 women with a twin gestation who were identified during the study period, 1059 met the study criteria. Of the 1059 women, 599 (57%) were classified as no significant discordance (pattern 1), 23 (2%) as early progressive discordance (pattern 2), 160 (15%) as early discordance with plateau (pattern 3), and 277 (26%) as late discordance (pattern 4). The associations of discordance pattern with preterm birth at <34 weeks' gestation and preeclampsia were strongest for pattern 2 (rates of 43% [adjusted relative risk, 3.43; 95% confidence interval, 2.10-5.62] and 17% [adjusted relative risk, 5.81; 95% confidence interval, 2.31-14.60], respectively), intermediate for pattern 3 (rates of 23% [adjusted relative risk, 1.82; 95% confidence interval, 1.28-2.59] and 6% [adjusted relative risk, 2.08; 95% confidence interval, 1.01-4.43], respectively), and weakest for pattern 4 (rates of 12% [adjusted relative risk, 0.96; 95% confidence interval, 0.65-1.42] and 4% [adjusted relative risk, 1.41; 0.68-2.92], respectively). In contrast, a single measurement of size discordance at 32 weeks' gestation showed no association with preeclampsia and only a weak association with preterm birth at <34 weeks' gestation. CONCLUSION: We identified 4 distinct discordance growth patterns among twins that demonstrated a dose-response relationship with adverse outcomes and seemed to be more informative than a single measurement of size discordance.

Mode of delivery and neonatal outcomes in extremely preterm Vertex/nonVertex twins.

BACKGROUND: One of the controversies in the management of twin gestations relates to mode of delivery, especially when the second twin is in a nonvertex presentation (Vertex/nonVertex pairs) and birth is imminent at extremely low gestation. OBJECTIVE: We hypothesized that, for Vertex/nonVertex twins born before 28 weeks' gestation, cesarean delivery would be associated with a lower risk of adverse neonatal outcomes than trial of vaginal delivery. Our aim was to test this hypothesis by comparing the neonatal outcomes of Vertex/nonVertex twins born before 28 weeks' gestation by mode of delivery using a large national cohort. STUDY DESIGN: This work is a retrospective cohort study of all twin infants born at 240/7 to 276/7 weeks' gestation and admitted to level III neonatal intensive care units participating in the Canadian Neonatal Network (2010-2017). Exposure is defined a trial of vaginal delivery for Vertex/nonVertex twins. Nonexposed (control) groups are defined as cases where both twins were delivered by cesarean delivery, either in vertex or nonvertex presentation (control group 1) or owing to the nonvertex presentation of the first twin (control group 2). Outcome measures are defined as a composite of neonatal death, severe neurologic injury, or birth trauma. RESULTS: A total of 1082 twin infants (541 twin pairs) met the inclusion criteria: 220 Vertex/nonVertex pairs, of which 112 had a trial of vaginal delivery (study group) and 108 had cesarean delivery for both twins (control group 1); 170 pairs with the first twin in nonvertex presentation, all of which were born by cesarean delivery (control group 2); and 151 pairs with both twins in vertex presentation (vertex or nonvertex). In the study group, the rate of urgent cesarean delivery for the second twin was 30%. The rate of the primary outcome in the study group was 42%, which was not significantly different compared with control group 1 (37%; adjusted relative risk, 0.93; 95% confidence interval, 0.71-1.22) or control group 2 (34%; adjusted relative risk, 1.20; 95% confidence interval, 0.92-1.58). The findings remained similar when outcomes were analyzed separately for the first and second twins. CONCLUSION: For preterm Vertex/nonVertex twins born at <28 weeks' gestation, we found no difference in the risk of adverse neonatal outcome between a trial of vaginal delivery and primary cesarean delivery. However, a trial of vaginal delivery was associated with a high rate of urgent cesarean delivery for the second twin.

Maternal cardiovascular disease after twin pregnancies complicated by hypertensive disorders of pregnancy: a population-based cohort study.

BACKGROUND: People whose singleton pregnancy is affected by hypertensive disorders of pregnancy (HDP) are at risk of future cardiovascular disease. It is unclear, however, whether this association can be extrapolated to twin pregnancies. We aimed to compare the association between HDP and future cardiovascular disease after twin and singleton pregnancies. METHODS: We conducted a population-based retrospective cohort study that included nulliparous people in Ontario, Canada, 1992-2017. We compared the future risk of cardiovascular disease among pregnant people from the following 4 groups: those who delivered a singleton without HDP (referent) and with HDP, and those who delivered twins either with or without HDP. RESULTS: The populations of the 4 groups were as follows: 1 431 651 pregnant people in the singleton birth without HDP group; 98 631 singleton birth with HDP; 21 046 twin birth without HDP; and 4283 twin birth with HDP. The median duration of follow-up was 13 (interquartile range 7-20) years. The incidence rate of cardiovascular disease was lowest among those with a singleton or twin birth without HDP (0.72 and 0.74 per 1000 person-years, respectively). Compared with people with a singleton birth without HDP, the risk of cardiovascular disease was highest among those with a singleton birth and HDP (1.47 per 1000 person-years; adjusted hazard ratio [HR] 1.81 [95% confidence interval (CI) 1.72-1.90]), followed by people with a twin pregnancy and HDP (1.07 per 1000 person-years; adjusted HR 1.36 [95% CI 1.04-1.77]). The risk of the primary outcome after a twin pregnancy with HDP was lower than that after a singleton pregnancy with HDP (adjusted HR 0.74 [95% CI 0.57-0.97]), when compared directly. INTERPRETATION: In a twin pregnancy, HDP are weaker risk factors for postpartum cardiovascular disease than in a singleton pregnancy.

Current Practice of Maternal-Fetal Medicine Specialists Regarding the Prevention and Management of Preterm Birth in Twin Gestations.

OBJECTIVE: To investigate the current practices of maternal-fetal medicine (MFM) specialists regarding the prevention and management of preterm birth (PTB) in twin pregnancies. METHODS: This was a cross-sectional study of Canadian MFM specialists. Participants responded to an anonymous survey regarding the prevention and management of PTB in twins, including lifestyle and gestational weight gain recommendations, cervical length screening, PTB prevention, and labour and delivery practices. RESULTS: Of 137 MFM specialists surveyed, 95 (69%) responded. Most MFM specialists recommend against activity restriction (77.9%), avoidance of sexual activity (96.7%), routine progesterone (97.8%), routine prophylactic cerclage (98.9%), and routine administration of antenatal corticosteroids (95.6%). There were considerable inconsistencies with respect to gestational weight gain management. Despite lack of support by guidelines, most MFM specialists reported using routine cervical length screening (97.8%) and progesterone for short cervix (92.3%). Over half (52.7%) of MFM specialists recommend cervical cerclage when the cervix is <15mm. In cases of PTB, most MFM specialists recommend vaginal delivery when twins are in vertex presentation (63%-75%). MFM specialists are less likely to recommend vaginal delivery when twin B is non-vertex (35%-41%). CONCLUSION: There is a considerable variation among MFM specialists regarding the prevention and management of PTB in twins, and the practice of many MFM specialists differs from that recommended by professional societies' guidelines. These findings underscore the necessity for high-quality studies and up-to-date recommendations.

Identification of the optimal growth chart and threshold for the prediction of antepartum stillbirth.

PURPOSE: To evaluate the effect of the choice growth chart and threshold used to define small for gestational age (SGA) on the predictive value of SGA for placenta-related or unexplained antepartum stillbirth. METHODS: A retrospective cohort study of all women with a singleton pregnancy who gave birth > 24 week gestation in a single center (2000-2016). The exposure of interest was SGA, defined as birth weight < 10th or < 25th centile according to three fetal growth charts (Hadlock et al., Radiology 181:129-133, 1991; intergrowth-21st (IG21), WHO 2017, and a Canadian birthweight-based reference-Kramer et al., Pediatrics 108:E35, 2001). The outcome of interest was antepartum stillbirth due to placental dysfunction or unknown etiology. Cases of stillbirth attributed to other specific etiologies were excluded. RESULTS: A total of 49,458 women were included in the cohort. There were 103 (0.21%) cases of stillbirth due to placental dysfunction or unknown etiology. For cases in the early stillbirth cluster (≤ 30 weeks), the detection rate was high and was similar for the three ultrasound-based fetal growth charts of Hadlock, IG21, and WHO (range 83.3-87.0%). In contrast, the detection rate of SGA for cases in the late stillbirth cluster (> 30 weeks) was low, being highest for WHO and Hadlock (36.7% and 34.7%, respectively), and lowest for IG21 (18.4%). Using a threshold of the 25th centile increased the detection rate for stillbirth by approximately 15-20% compared with that achieved by the 10th centile cutoff. CONCLUSION: At > 30 week gestation, the Hadlock or WHO fetal growth charts provided the best balance between detection rate and false positive rate for stillbirth.

Trial of labor after previous single cesarean delivery in grand-multiparous women: a retrospective cohort study.

PURPOSE: To compare pregnancy outcomes in grand-multiparous (GMP) women with and without one previous cesarean delivery (CD), and to evaluate the number of previous successful vaginal deliveries after a CD needed to reduce the complication rate of trials of labor after a previous CD. METHODS: This is a retrospective cohort study of women with singleton pregnancy at term who had a trial of vaginal delivery between 2007 and 2014 at a tertiary medical center. We compared pregnancy outcomes in GMP women with and without one previous cesarean delivery. The primary outcome was mode of delivery and secondary outcomes were uterine rupture and composite maternal and neonatal morbidity. For the secondary objective, we compared pregnancy outcomes in women in TOLAC, stratified by the number of previous vaginal deliveries. RESULTS: Overall, 2815 GMP women met the study criteria, of which 310 (11%) had a previous cesarean delivery. The rate of a successful vaginal deliveries (VBAC) was similar, regardless of the presence of a previous cesarean delivery. No other differences in outcomes were found between the groups. In a secondary analysis, it was found that the presence of a single previous VBAC (compared to no previous VBACs) increased the odds of achieving a vaginal delivery in the next trial of labor after cesarean delivery (TOLAC) (aOR 5.66; 95% CI 3.73-8.60), and decreased the risk of maternal or neonatal adverse outcomes (aOR 0.62; 95% CI 0.39-0.97, and aOR 0.49; 95% CI 0.25-0.97, respectively). Multiple prior VBACs (as compared to a single prior VBAC) did not increase the odds of achieving another VBAC. CONCLUSION: Grand-multiparous women with and without previous uterine scar have comparable pregnancy outcomes. Additionally, after the first VBAC, additional successful VBACs do not improve the success rate in the next TOLAC.

Mild thrombocytopenia prior to elective cesarean section is an independent risk factor for blood transfusion.

PURPOSE: Thrombocytopenia is the second most common hematological disorder in pregnancy and complicates approximately 10% of all pregnancies. The data regarding the association of mild thrombocytopenia in women undergoing cesarean section and risk of bleeding or bleeding-related complications are scarce. Thus, the aim of the current study was to assess the association of mild thrombocytopenia with hemorrhage-related morbidities, among patients undergoing elective cesarean section. METHODS: We performed a retrospective cohort study, in a single tertiary university-affiliated medical center, between 1 January 2012 and 31 May 2019. Medical charts of women who underwent elective cesarean section at term (37+0/7-41 + 6/7 weeks of gestations) were retrieved and analyzed. We compared women with mild thrombocytopenia (platelet count of 100-149 × 103/µL) to women with normal platelet count (150-450 × 103/µL). The primary outcome was the need for red blood cell transfusion during the index admission. A secondary outcome was severe bleeding not requiring blood transfusion defined as postpartum hemoglobin decline of ≥ 3 g/dL as compared to the prepartum levels. RESULTS: During the study period, 1577 women were included in the final analysis, of them 396 (25.11%) had mild thrombocytopenia prior to delivery. As compared to the control group, women with mild thrombocytopenia had higher rates of blood transfusion (3.79 vs. 1.52%, p = 0.01), and had a significant decline in hemoglobin levels. In a multivariable logistic regression model, mild thrombocytopenia was independently associated with blood transfusion with adjusted OR of 2.34 (95% CI 1.10-4.96, p = 0.03). CONCLUSION: Preoperative mild thrombocytopenia is associated with an increased risk of blood loss and blood transfusion in women undergoing elective CS. More studies are required to assess those observations in context of urgent cesarean sections and whether any preventive measures can reduce the risk for bleeding.