Background Although preterm birth less than 37 weeks gestation is the leading cause of neonatal morbidity and mortality in the United States, the majority of data regarding preterm neonatal outcomes come from older studies, and many reports have been limited to only very preterm neonates. Delineation of neonatal outcomes by delivery gestational age is needed to further clarify the continuum of mortality and morbidity frequencies among preterm neonates. Objective We sought to describe the contemporary frequencies of neonatal death, neonatal morbidities, and neonatal length of stay across the spectrum of preterm gestational ages. Study Design Secondary analysis of an obstetric cohort of 115,502 women and their neonates who were born in 25 hospitals nationwide, 2008–2011. All live born non-anomalous singleton preterm (23.0–36.9 weeks of gestation) neonates were included in this analysis. The frequency of neonatal death, major neonatal morbidity (intraventricular hemorrhage grade III/IV, seizures, hypoxic-ischemic encephalopathy, necrotizing enterocolitis stage II/III, bronchopulmonary dysplasia, persistent pulmonary hypertension), and minor neonatal morbidity (hypotension requiring treatment, intraventricular hemorrhage grade 1/2, necrotizing enterocolitis stage 1, respiratory distress syndrome, hyperbilirubinemia requiring treatment) were calculated by delivery gestational age; each neonate was classified once by the worst outcome they met criteria for. Results 8,334 deliveries met inclusion criteria. There were 119 neonatal deaths (1.4%). 657 (7.9%) neonates had major morbidity, 3,136 (37.6%) had minor morbidity, and 4,422 (53.1%) survived without any of the studied morbidities. Deaths declined rapidly with each advancing week of gestation. This decline in death was accompanied by an increase in major neonatal morbidity, which peaked at 54.8% at 25 weeks of gestation. As frequencies of death, and major neonatal morbidity fell, minor neonatal morbidity increased, peaking at 81.7% at 31 weeks of gestation. The frequency of all morbidities fell beyond 32 weeks. Neonatal length of hospital stay decreased significantly with each additional completed week of pregnancy; among babies delivered from 26 to 32 weeks of gestation, each additional week in utero reduced the subsequent length of neonatal hospitalization by a minimum of 8 days. The median post-menstrual age at discharge nadired at 35.7 weeks post-menstrual age for babies born at 32–33 weeks of gestation. Conclusions Our data show that there is a continuum of outcomes, with each additional week for gestation conferring survival benefit while reducing the length of initial hospitalization. These contemporary data can be useful for patient counseling regarding preterm outcomes.

OBJECTIVE: To evaluate the association between gestational weight gain and maternal and neonatal outcomes in a large, geographically-diverse cohort. METHODS: Trained chart abstractors at 25 hospitals obtained maternal and neonatal data for all deliveries on randomly selected days over 3 years (2008–2011). Gestational weight gain was derived using weight at delivery minus pre-pregnancy or first-trimester weight and categorized as below, within or above the Institute of Medicine (IOM) guidelines in this retrospective cohort study. Maternal (primary or repeat cesarean birth, 3rd or 4th degree lacerations, severe postpartum hemorrhage, hypertensive disease of pregnancy) and neonatal (preterm birth, shoulder dystocia, macrosomia, hypoglycemia) outcomes were compared among women in the gestational weight gain categories in unadjusted and adjusted analyses with ORs and 95%CI reported. Covariates included age, race-ethnicity, tobacco use, insurance type, parity, prior cesarean birth, pregestational diabetes, hypertension, and hospital type. RESULTS: Of the 29,861 women included, 51% and 21% had gestational weight gain above and below the guidelines, respectively. There was an association between gestational weight gain above the IOM guidelines and cesarean birth in both nulliparous women (aOR 1.44, 95%CI 1.31–1.59) and multiparous women (aOR 1.26, 95%CI 1.13–1.41) and hypertensive diseases of pregnancy in nulliparous and multiparous women combined (aOR 1.84, 95%CI 1.66–2.04). For the neonatal outcomes, gestational weight gain above the IOM guidelines was associated with shoulder dystocia (aOR 1.74, 95%CI 1.41-.2.14), macrosomia (aOR 2.66, 95%CI 2.03–3.48), and neonatal hypoglycemia (aOR 1.60, 95%CI 1.16–2.22). Gestational weight gain below the guidelines was associated with spontaneous (aOR 1.50, 95%CI 1.31–1.73) and indicated (aOR 1.34, 95%CI 1.12–1.60) preterm birth. CONCLUSIONS: In a large, diverse cohort with prospectively collected data, gestational weight gain below or above guidelines is associated with a variety of adverse pregnancy outcomes.

Objective To compare morbidity among small-for-gestational-age (SGA; birthweight [BW] < 10th percentile for gestational age), appropriate-for-gestational-age (AGA; BW 10-90th percentile; reference group), and large-for-gestational-age (LGA; BW > 90th percentile) neonates in apparently uncomplicated pregnancies at term (≥ 37 weeks). Material and Methods This secondary analysis, derived from an observational obstetric cohort of 115,502 deliveries, included women with apparently uncomplicated pregnancies of non-anomalous singletons who had confirmatory ultrasound dating no later than the second trimester, and who delivered between 370 and 426 weeks. We used two different composite neonatal morbidity outcomes: hypoxic composite neonatal morbidity for SGA and traumatic composite neonatal morbidity for LGA neonates. Log Poisson relative risks (aRR) with 95% confidence intervals (CI), adjusted for potential confounding factors (nulliparity, body mass index, insurance status, and neonatal sex) were calculated. Results Among the 63,436 women who met our inclusion criteria, SGA occurred in 7.9% (n=4,983) and LGA in 8.3% (n=5,253). Hypoxic composite neonatal morbidity was significantly higher in SGA (1.1%) vs. AGA (0.7%; aRR 1.44, 95% CI 1.07-1.93) but similar between LGA (0.6%) vs. AGA (aRR 0.84; 95% CI 0.58-1.22). Traumatic composite neonatal morbidity was significantly higher in LGA (1.9%) vs. AGA (1.0%; aRR 1.88, 95% CI 1.51-2.34)) but similar in SGA (1.3%) vs. AGA (aRR 1.28; 95% CI 0.98-1.67). Conclusions Among women with uncomplicated pregnancies, hypoxic composite neonatal morbidity is more common with SGA neonates and traumatic–composite neonatal morbidity is more common with LGA neonates.

Globally, about 1% of pregnant women are persistently infected with the hepatitis C virus (HCV)1. Vertical transmission occurs in 3–5% of cases2 and accounts for most new childhood HCV infections1,3. HCV-specific CD8+ cytotoxic T-lymphocytes (CTLs) play a vital role in the clearance of acute infections4–6, but in the 60–80% of infections that persist these cells become functionally exhausted or select mutant viruses that escape T-cell recognition7–9. Increased HCV replication during pregnancy10,11 suggests that maternofetal immune tolerance mechanisms12 may further impair HCV-specific CTLs, limiting their selection pressure on persistent viruses. To assess this possibility, we characterized the circulating viral quasispecies during and after consecutive pregnancies. This revealed a loss of some escape mutations in class I epitopes in pregnancy associated with emergence of more fit viruses13. CTL selection pressure was reimposed after childbirth, when escape mutations in these epitopes again predominated in the quasispecies and viral load dropped sharply14. Importantly, viruses transmitted perinatally were those with enhanced fitness due to reversion of escape mutations. Our findings indicate that immunoregulatory changes of pregnancy reduce CTL selection pressure on HCV class I epitopes, thereby facilitating vertical transmission of viruses with optimized replicative fitness.

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