Association of extremes of prepregnancy BMI with the clinical presentations of preterm birth.

Objective: The purpose of this study was to examine associations between the prepregnancy maternal body mass index (BMI) across the 3 clinical presentations of preterm birth (PTB).

Study Design: We conducted a retrospective cohort study of the records of 11,726 women. The World Health Organization International Classification was used to categorize BMI.