Gestational weight gain and preterm birth: disparities in adolescent pregnancies.

Objective: To examine racial differences in the association between gestational weight gain and preterm birth subtypes among adolescents.

Study Design: We conducted a retrospective cohort study of 211 403 adolescents using 2012 United States natality data. The outcome was preterm birth and the primary exposure was gestational weight gain. Multinomial logistic regression analyses were used to estimate adjusted odds ratios, stratified by race and body mass index (BMI).

Results: Black and White mothers who gained below the recommendations had increased risks for spontaneous preterm birth in all BMI categories, except obese. All Hispanic mothers who gained below the recommendations had increased risks of spontaneous preterm birth. White normal and overweight mothers and Black, Hispanic and Other normal weight mothers who exceeded the recommendations had decreased risks of spontaneous preterm birth.

Conclusion: The effect of gestational weight gain on spontaneous and medically indicated preterm birth is modified by race and BMI.