Maternal vaccination against COVID-19 and neonatal outcomes during Omicron: INTERCOVID-2022 study.

BACKGROUND: In early 2023, when Omicron was the variant of concern, we showed that vaccinating pregnant women decreased the risk for severe COVID-19-related complications and maternal morbidity and mortality. OBJECTIVE: This study aimed to analyze the impact of COVID-19 during pregnancy on newborns and the effects of maternal COVID-19 vaccination on neonatal outcomes when Omicron was the variant of concern. STUDY DESIGN: INTERCOVID-2022 was a large, prospective, observational study, conducted in 40 hospitals across 18 countries, from November 27, 2021 (the day after the World Health Organization declared Omicron the variant of concern) to June 30, 2022, to assess the effect of COVID-19 in pregnancy on maternal and neonatal outcomes and to assess vaccine effectiveness. Women diagnosed with laboratory-confirmed COVID-19 during pregnancy were compared with 2 nondiagnosed, unmatched women recruited concomitantly and consecutively during pregnancy or at delivery. Mother-newborn dyads were followed until hospital discharge. The primary outcomes were a neonatal positive test for COVID-19, severe neonatal morbidity index, severe perinatal morbidity and mortality index, preterm birth, neonatal death, referral to neonatal intensive care unit, and diseases during the neonatal period. Vaccine effectiveness was estimated with adjustment for maternal risk profile. RESULTS: We enrolled 4707 neonates born to 1577 (33.5%) mothers diagnosed with COVID-19 and 3130 (66.5%) nondiagnosed mothers. Among the diagnosed mothers, 642 (40.7%) were not vaccinated, 147 (9.3%) were partially vaccinated, 551 (34.9%) were completely vaccinated, and 237 (15.0%) also had a booster vaccine. Neonates of booster-vaccinated mothers had less than half (relative risk, 0.46; 95% confidence interval, 0.23-0.91) the risk of being diagnosed with COVID-19 when compared with those of unvaccinated mothers; they also had the lowest rates of preterm birth, medically indicated preterm birth, respiratory distress syndrome, and number of days in the neonatal intensive care unit. Newborns of unvaccinated mothers had double the risk for neonatal death (relative risk, 2.06; 95% confidence interval, 1.06-4.00) when compared with those of nondiagnosed mothers. Vaccination was not associated with any congenital malformations. Although all vaccines provided protection against neonatal test positivity, newborns of booster-vaccinated mothers had the highest vaccine effectiveness (64%; 95% confidence interval, 10%-86%). Vaccine effectiveness was not as high for messenger RNA vaccines only. Vaccine effectiveness against moderate or severe neonatal outcomes was much lower, namely 13% in the booster-vaccinated group (all vaccines) and 25% and 28% in the completely and booster-vaccinated groups, respectively (messenger RNA vaccines only). Vaccines were fairly effective in protecting neonates when given to pregnant women ≤100 days (14 weeks) before birth; thereafter, the risk increased and was much higher after 200 days (29 weeks). Finally, none of the neonatal practices studied, including skin-to-skin contact and direct breastfeeding, increased the risk for infecting newborns. CONCLUSION: When Omicron was the variant of concern, newborns of unvaccinated mothers had an increased risk for neonatal death. Neonates of vaccinated mothers had a decreased risk for preterm birth and adverse neonatal outcomes. Because the protective effect of COVID-19 vaccination decreases with time, to ensure that newborns are maximally protected against COVID-19, mothers should receive a vaccine or booster dose no more than 14 weeks before the expected date of delivery.

Association of Chorioamnionitis with Cerebral Palsy at Two Years after Spontaneous Very Preterm Birth: The EPIPAGE-2 Cohort Study.

OBJECTIVE: To assess whether chorioamnionitis is associated with cerebral palsy (CP) or death at 2 years' corrected age in infants born before 32 weeks of gestation after spontaneous birth. STUDY DESIGN: EPIPAGE-2 is a national, prospective, population-based cohort study of children born preterm in France in 2011; recruitment periods varied by gestational age. This analysis includes infants born alive after preterm labor or preterm premature rupture of membranes from 240/7 to 316/7 weeks of gestation. We compared the outcomes of CP, death at 2 years' corrected age, and "CP or death at age 2" according to the presence of either clinical chorioamnionitis or histologic chorioamnionitis. All percentages were weighted by the duration of the recruitment period. RESULTS: Among 2252 infants born alive spontaneously before 32 weeks of gestation, 116 (5.2%) were exposed to clinical chorioamnionitis. Among 1470 with placental examination data available, 639 (43.5%) had histologic chorioamnionitis. In total, 346 infants died before 2 years and 1586 (83.2% of the survivors) were evaluated for CP at age 2 years. CP rates were 11.1% with and 5.0% without clinical chorioamnionitis (P = .03) and 6.1% with and 5.3% without histologic chorioamnionitis (P = .49). After adjustment for confounding factors, CP risk rose with clinical chorioamnionitis (aOR 2.13, 95% CI 1.12-4.05) but not histologic chorioamnionitis (aOR 1.21, 95% 0.75-1.93). Neither form was associated with the composite outcome "CP or death at age 2." CONCLUSIONS: Among infants very preterm born spontaneously, the risk of CP at a corrected age of 2 years was associated with exposure to clinical chorioamnionitis but not histologic chorioamnionitis.

Impact of Latency Duration on the Prognosis of Preterm Infants after Preterm Premature Rupture of Membranes at 24 to 32 Weeks' Gestation: A National Population-Based Cohort Study.

OBJECTIVE: To assess the impact of latency duration on survival, survival without severe morbidity, and early-onset sepsis in infants born after preterm premature rupture of membranes (PPROM) at 24-32 weeks' gestation. STUDY DESIGN: This study was based on the prospective national population-based Etude Épidémiologique sur les Petits Ȃges Gestationnels 2 cohort of preterm births and included 702 singletons delivered in France after PPROM at 24-32 weeks' gestation. Latency duration was defined as the time from spontaneous rupture of membranes to delivery, divided into 4 periods (12 hours to 2 days [reference], 3-7 days, 8-14 days, and >14 days). Multivariable logistic regression was used to assess the relationship between latency duration and survival, survival without severe morbidity at discharge, or early-onset sepsis. RESULTS: Latency duration ranged from 12 hours to 2 days (18%), 3-7 days (38%), 8-14 days (24%), and >14 days (20%). Rates of survival, survival without severe morbidity, and early-onset sepsis were 93.5% (95% CI 91.8-94.8), 85.4% (82.4-87.9), and 3.4% (2.0-5.7), respectively. A crude association found between prolonged latency duration and improved survival disappeared on adjusting for gestational age at birth (aOR 1.0 [reference], 1.6 [95% CI 0.8-3.2], 1.2 [0.5-2.9], and 1.0 [0.3-3.2] for latency durations from 12 hours to 2 days, 3-7 days, 8-14 days, and >14 days, respectively). Prolonged latency duration was not associated with survival without severe morbidity or early-onset sepsis. CONCLUSION: For a given gestational age at birth, prolonged latency duration after PPROM does not worsen neonatal prognosis.

Influence of gestational age on fibrinolysis from birth to postnatal day 10.

OBJECTIVE: To compare components of the fibrinolytic cascade in newborns of gestational age ranging from extreme prematurity to full term, at birth and for the next 10 days, and in their mothers at delivery. STUDY DESIGN: We studied 10 extremely preterm neonates, 10 very preterm neonates, 10 moderately preterm neonates, 10 full-term neonates, and their mothers (n = 40). We measured the antigen levels of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitors 1 (PAI-1) and 2 (PAI-2), and thrombin-activatable fibrinolysis inhibitor, as well as PAI-1 activity, in neonates at birth and on postnatal days 3 and 10 and in mothers at delivery. RESULTS: On day 10, both PAI-1 antigen and activity were higher in extremely preterm neonates than in full-term neonates (P = .004 and <.0006, respectively), and the t-PA/PAI-1 activity ratio was lower in the extremely preterm and very preterm neonates compared with the full-term neonates (P = .002 and .017, respectively). No significant differences in the fibrinolytic system components were seen among the 4 groups of mothers. CONCLUSIONS: The development of fibrinolysis suppression in extremely preterm infants within 10 days after birth may contribute to the increased risk of periventricular hemorrhagic infarction in these infants.