Objective Previous studies comparing the COVID-19 pandemic period to prepandemic periods reported either no change or a decrease in extremely preterm birth (PTB) rates during the pandemic. 1, 2 These studies evaluated a limited number of potential PTB confounders and a short pandemic period. We aimed to determine the change in PTB rate and neonatal outcomes during the pandemic in comparison to prepandemic periods by evaluating multiple obstetrical characteristics, during more than three pandemic months. Study design We compared maternal, obstetrical and neonatal outcomes of singleton pregnancies at the Sheba Medical Center, Israel, during three periods: from 20/03/2020 (date of implementation of governmental state of lockdown) to 27/06/2020 (group 1), a parallel period in 2019 (group 2), and to another group that included the parallel annual periods in 2011-2019 (group 3) (see Table). We also compared maternal and pregnancy characteristics during the pandemic and corresponding prepandemic period in 2019 between pregnancies complicated by PTB <34 0/7 versus ≥34 0/7 weeks (see Table). Multivariate regression analysis was performed in order to study independent factors associated with PTB. The institutional review board approved this study (7068-20-SMC, 03/30/2020). Results There were 2,594 deliveries during the pandemic period (group 1) and 2,742 and 28,686 deliveries in the prepandemic periods (groups 2 and 3, respectively). Maternal and obstetrical characteristics did not differ between groups 1 and 2. Predelivery hemoglobin levels were higher in the pandemic period. PTB <34 0/7 weeks rate was significantly lower in the pandemic period compared to group 2 (OR 0.45 95% CI 0.30-0.68, p<0.001), as was the rate of composite neonatal outcome (OR 0.76 95% CI 0.59-0.96, p=0.023). Age, body mass index, parity, diabetes rates and hematologic characteristics differed between groups 1 and 3 with significantly higher predelivery hemoglobin levels in group 1. PTB <34 0/7 weeks rate was lower in the pandemic period (OR 0.60 95% CI 0.41-0.85, p=0.004). On multivariate regression analysis, delivering during the pandemic period was independently associated with a decreased risk for delivery <34 0/7 weeks (adjusted OR 0.29, 95% CI 0.15-0.56, p=0.001). Conclusion We observed more than 50% reduction in the rate of PTB <34 0/7 weeks of gestation, possibly resulting in improved neonatal outcome.

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How chemotherapy affects dormant ovarian primordial follicles is unclear. The 'burnout' theory, studied only in mice, suggests cyclophosphamide enhances primordial follicle activation. Using 4-hydroperoxycyclophosphamide (4hc) and phosphoramide mustard (PM), this study assessed how the active cyclophosphamide metabolites 4-hydroxycyclophosphamide (4-OHC) and PM, affect human primordial follicles. Frozen-thawed human ovarian samples were sliced and cultured with basic culture medium (cultured controls) or with 4hc/PM (3 µmol/l/10 µmol/l) (treated samples) for 24-48 h. Follicular counts and classification, Ki67 and anti-Müllerian hormone (AMH) immunohistochemistry and an apoptosis assay were used for evaluation, and 17β-oestradiol and AMH were measured in spent media samples. Generally, there was primordial follicle decrease and elevated developing follicle rates in treated samples compared with cultured (P = 0.04 to P < 0.0005) and uncultured controls (P < 0.05 to P < 0.0001). No traces of apoptosis were found. There were almost twicethe levels of AMH and 17β-oestradiol in treated compared with untreated samples (AMH with 4hc 3 µmol/l; P = 0.04). All follicles stained positively for AMHincluded treated samples. Ki67 positive staining was noted in all samples. Cyclophosphamide metabolites seem to enhance human primordial follicle activation to developing follicles, in vitro. Study findings support the 'burnout' theory as the mechanism of chemotherapy-induced ovarian toxicity.

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COVID-19 infection imposes a risk for pregnant individuals and may lead to adverse maternal and obstetric outcomes. This is a retrospective cohort study of all women giving birth between March and July 2021 at a single tertiary center. Obstetric and neonatal outcomes were compared between vaccinated and non-vaccinated pregnant women with singleton pregnancies. Women with prior COVID-19 infection, multiple gestations and stillbirth were excluded from the study. Of 4708 women who delivered during the study period, 3700 met the eligibility criteria, of whom 3240 were vaccinated during pregnancy. Compared with the non-vaccinated group, the vaccinated group was characterized by a lower rate of smoking (3.70% vs 6.67%, p = 0.0028), whereasother maternal characteristics were not significantly different. Multivariable analysis demonstrated that COVID-19 mRNA vaccination was not significantly associated with increased risk of preterm birth as well as other adverse obstetric outcomes including hypertensive diseases of pregnancy, cesarean delivery and small for gestational age. However, a significantly lower risk for meconium-stained amniotic fluid was observed among the vaccinated group (adjusted odds ratio 0.63; 95% confidence interval, 0.46–0.86, p = 0.0039). Moreover, the vaccine was not significantly associated with increased risk of neonatal adverse outcomes including respiratory complications and NICU hospitalization. In conclusion, BNT162b2 messenger RNA vaccination during pregnancy was not associated with an increased rate of adverse obstetric and neonatal outcomes. Therefore, in view of its safety on one hand, and the risk associated with COVID-19 disease in pregnancy on the other hand, BNT 162b2 COVID-19 vaccine should be recommended for pregnant women.

A total of 410 measurements were included. Of them 255 were normal and 155 abnormal. The CC length/estimated fetal weight (EFW) ratio had the strongest linear association with GA (R = 0.929). Applying charts using this ratio to the normal group, significantly increased the percent of CC length measurements defined as normal from 84.7 to 94.5% (p < .001). Conversely, applying these charts to the abnormal group nonsignificantly decreased the number of measurement defined as normal from 89 to 83.2% (p = .137) Conclusions: The CC length/EFW ratio is strongly and linearly associated with GA. Using this personalized ratio may improve the diagnostic accuracy of CC evaluation by adjusting the CC length to the fetus natural proportions.

The obesity and preterm birth paradox is an example of what has been described as 'Simpson's Paradox'. Unmeasured confounding factors mediated by comorbidities may explain the observed protective effect of obesity upon conditioning on the presence or absence of comorbidities and thus resolve the paradox.

We developed and externally validated a machine-learning model integrating maternal risk modifiers with fetal biometry for prediction of shoulder dystocia (ShD). The model was significantly more accurate than was prediction based on estimated fetal weight either alone or combined with maternal diabetes and was able to stratify the risk of ShD and neonatal injury in the context of suspected macrosomia. What are the clinical implications of this work? We demonstrated the potential clinical efficacy of applying this model to stratify the risk of ShD and related newborn injury among women carrying a fetus with estimated fetal weight ≥ 4000 g.