The effects of maternal obesity on perinatal outcomes among those born small for gestational age

Background: Maternal obesity has been associated with higher birth weight. Small for gestational age (SGA) neonates born to obese women may be associated with pathological growth with increased neonatal complications. Methods: This was a retrospective cohort study of all non-anomalous singleton neonates born in Texas from 2006-2011. Analyses were limited to births between 34 and 42 weeks gestation with birth weight <= 10th percentile. Results were stratified by maternal pre-pregnancy BMI class. The risk for stillbirth, neonatal death, neonatal intensive care unit (NICU) admission and fiveminute Apgar scores<7 were estimated for each obesity class and compared to the normal weight group. Multivariable logistic regression analyses were performed to control for potential confounding variables. Results: The rate of stillbirth was 1.4/1000 births for normal weight women, and 2.9/1000 among obese women (p<0.001, aOR: 1.83 [1.43, 2.34]). The rate of neonatal deaths among normal weight women was 4.3/1000 births, whereas among obese women it was 4.7/1000 (p = 0.94, aOR: 1.10 [0.92, 1.30]). A dose-dependent relationship between maternal obesity and stillbirths was seen, but not for other neonatal outcomes. Conclusion: Among SGA neonates, maternal pre-pregnancy obesity was associated with increased risks for stillbirth, NICU admission and low Apgar scores but not neonatal death.