Maternal weight gain and neonatal outcomes in women with class III obesity.

Objective: Obesity in the USA continues to be a prominent medical and public health concern. Due to increasing rates of maternal obesity, the current Institute of Medicine (IOM) guidelines recommend 11-20 pounds of total weight gain during pregnancy in women with a BMI ≥30 kg/m². The impact of maternal obesity on adverse perinatal outcomes has been well documented however, there is minimal data on the effect of gestational weight gain on neonatal outcomes. In this study, we assessed the association between gestational weight gain (GWG) and neonatal outcomes at term in women with class III obesity.Study design: A retrospective cohort of women delivering at a tertiary care institution between July 2013 and December 2017 with a first-trimester baseline BMI ≥40 kg/m² was studied. Pregnancies complicated by multiple gestations, preterm delivery, fetal anomalies, intrauterine fetal demise or with missing data were excluded. The primary outcome was a composite of adverse neonatal outcomes including 5 min Apgar <7, neonatal intubation, grade 3 or 4 intraventricular hemorrhage (IVH), confirmed neonatal sepsis or Neonatal Intensive Care Unit (NICU) admission. Secondary outcomes included individual components of composite and NICU admission for >7 days. Demographic, pregnancy complications & delivery characteristics of women who gained more than IOM guidelines (>20 lbs.) were compared to women who gained at or less than IOM guidelines (≤20 lbs.) using bivariate statistics. Stepwise backward regression was used to estimate the odds of outcomes as appropriate.Results: Of 374 women included, 144 (39.5%) gained more than guidelines. Women who gained above IOM recommendations were less likely to be multiparous and use tobacco. Additional demographic, obstetric and delivery characteristics, including BMI at the entry to care, did not differ. The neonatal composite occurred in 30 (8.0%) of all neonates; corresponding to 11.1% of women who gained more than IOM recommendations and 6.1% of those who gained at or below recommendations (p = .12, OR = 1.71, 95%CI 0.74-3.96). Additionally, neonates born to women gaining more than IOM recommendations were more likely to be admitted to the NICU (10.4 vs. 4.3%, p = .03) and have a NICU length of stay >7 days (6.9 vs. 2.2%, p = .03). When adjusted for mode of delivery, delivery BMI, tobacco use, and chorioamnionitis, women who gained more were not more likely to have an adverse neonatal outcome (1.54, 95%CI 0.62-3.80), they were 3.6 times more likely to have a neonate admitted to the NICU for more than 7 days (95%CI 1.00-13.42).Conclusions: In women with class III obesity, excess gestational weight gain was associated with increased odds of NICU stay >7 days, with trends toward increased NICU admission risk, further emphasizing the importance of appropriate weight gain counseling in this population at risk.