Maternal Obesity and Risk of Preterm Birth and Low Birthweight in Hawaii PRAMS, 2000-2011

Objective Maternal obesity is a risk factor for preterm birth, a leading cause of infant morbidity and mortality. Native Hawaiian and other Pacific Islanders (NHOPI) have high rates of poor birth outcomes. Despite the high rates of obesity in NHOPI in Hawaii, the association with preterm birth has not been examined in this population. Methods We performed a retrospective cohort study of 20,061 women using data collected by Hawaii's Pregnancy Risk Assessment Monitoring System (PRAMS) from 2000 to 2011. We investigated the contribution of maternal age, pre-pregnancy BMI, gestational diabetes, hypertension, race, socioeconomic status, and smoking to our primary outcomes of preterm birth and low birthweight using multivariable logistic regression, stratified by NHOPI versus non-NHOPI race. Results Pre-pregnancy obesity was more common in NHOPI than non-NHOPI women (23.9 and 10.5%, respectively; p < 0.01). Overall, the risk for preterm birth increased with maternal obesity (BMI ≥ 30.0; aOR = 1.24, 95% CI 1.06-1.45, p < 0.01), compared with normal weight women. Among NHOPI women, the prevalence of preterm birth was elevated compared with non-NHOPI women although the prevalence of low birth weight was lower. After adjusting for confounders, risk for preterm birth and low birth weight were elevated in NHOPI women compared with White women. Maternal obesity did not significantly affect the risk of prematurity within the NHOPI group. Conclusions for Practice Our study demonstrates an association between maternal pre-pregnancy obesity and preterm deliveries in Hawaii. NHOPI have high rates of pre-pregnancy obesity as well as increased risk of both preterm delivery and low birthweight when compared to White women. Further data are needed to assess interactions between race, maternal health, and neonatal morbidity, and to identify ways to improve birth outcomes for minority populations in the state of Hawaii.