Objective: To determine whether an association exists between antenatal antibiotic exposure and incidence of necrotizing enterocolitis (NEC) in low birth weight infants.Study Design: A retrospective case-control study was performed on all infants with a diagnosis of NEC born at our institition between 1988 and 2006. Medical histories of all infants with a diagnosis of NEC XBell's stage IIA and matched controls without NEC were reviewed. Maternal and neonatal characteristics were compared using the Mantel-Haenszel chi-square procedure, and logistic regression models were constructed to account for confounding.Result: Clinical data for 97 matched pairs were analyzed. The adjusted odds ratio (OR) for antenatal exposure to ampicillin was significantly greater for infants who developed NEC (OR 2.3, 95% confidence interval 1.1, 4.8, P ¼ 0.003) than for control infants. Conclusion:Infants who developed NEC were more likely to have a history of in utero exposure to ampicillin in the immediate antepartum period than infants who did not develop NEC.

Objective To estimate the efficacy of a rescue course of antenatal corticosteroids in twin pregnancies.Design Retrospective cohort study.Setting Tertiary-care centre.Population Twins born from 24 to <34 weeks of gestation in a single maternal and fetal medicine practice from 2006 to 2011.Methods We compared neonatal outcomes in 88 twins exposed to a single course of corticosteroids with outcomes in 42 twins exposed to two courses of corticosteroids: the initial course and a single rescue course. Analyses were adjusted to control for correlation between twins born to the same mother.Main outcome measure Short-term neonatal respiratory morbidity.Results Rescue corticosteroids were associated with fewer days of mechanical ventilation (7.3 ± 3.3 versus 33.9 ± 25.3 days, P = 0.003), fewer days with a fraction of inspired oxygen of >21% (6.3 ± 4.3 versus 33.3 ± 25.8 days, P = 0.003), a lower incidence of mechanical ventilation >14 days or death while on mechanical ventilation (0 versus 12.5%, P = 0.016), and a lower incidence of retinopathy of prematurity (0 versus 12.5%, P = 0.016). The proportion of neonates with respiratory distress syndrome did not differ between the groups (adjusted odds ratio 1.28, 95% confidence interval 0.50-3.26). There were no differences found for birthweight, head circumference and length.Conclusions In twins born before 34 weeks of gestation, exposure to rescue corticosteroids may be associated with improved neonatal outcomes. Further studies are warranted to assess the effect of rescue corticosteroids in twin pregnancies.

OBJECTIVE: To compare the incidence of small for gestation age (SGA) neonates in twin gestations conceived by ovulation induction or in vitro fertilization with that of twins conceived spontaneously. STUDY DESIGN: A retrospective cohort study was conducted. Subjects were delivered by a single obstetric practice between 2005 and 2011 at the Mount Sinai Medical Center. Maternal and neonatal data were recorded. Our primary outcome was the incidence of SGA, defined as birth weight <10th percentile, from the three modes of conception. Chi square, ANOVA, Fisher's exact test, the Kruskal-Wallis test, the Mantel-Haenszel test, and logistic regression were used in the analysis. RESULTS: In unadjusted analysis, using the records of 756 infants from 378 mothers of twin pregnancies, twins conceived by ovulation induction had an increased incidence of SGA (28.1%) compared to those conceived spontaneously (17.1%) and by in vitro fertilization (16.5%, p = 0.006). In a logistic regression model accounting for correlated responses between twins and adjusting for gestational age, gender, chorionicity, and maternal age, the odds ratio (95% confidence interval [CI]) of SGA for the ovulation induction group compared to the spontaneous conception group was 2.64 (1.38-5.05, p = 0.003). The odds ratio (95% CI) of SGA for the in vitro fertilization group compared to the spontaneous conception group was 1.51 (0.88-2.61, p = 0.135). CONCLUSIONS: When adjusted for gestational age, gender, chorionicity, and maternal age, twin neonates conceived by ovulation induction, but not those conceived by in vitro fertilization, had increased odds of SGA compared to those conceived spontaneously.

This is a case of a neonate born with a respiratory acidosis with a compensatory metabolic alkalosis. This case demonstrates placental physiology of gas exchange as well as the blunted ventilatory response in the neonate from chronic hypercapnia.