Maternal prepregnancy BMI and gestational weight gain

Objective The objective of this study was to evaluate whether neonatal birth weight was affected more by prepregnancy BMI or by gestational weight gain. Design This study was a prospective observational cohort study. Setting The study was carried out at University Teaching Hospital, Kasr Al Aini, Cairo, Egypt. Patients and methods Two hundred and seventy-nine pregnant women fulfilled the inclusion criteria. The study population was divided according to the WHO classification of BMI into four groups: underweight (<18.5), normal weight (18.5–24.9), overweight (25–29.9), and obese (≥30). They were also divided according to the Institute of Medicine guidelines of gestational weight gain into three categories: inadequate, adequate, and excessive weight gain. Neonatal birth weight was measured, and the correlation between neonatal birth weight and both prepregnancy BMI and gestational weight gain was assessed to determine the stronger correlation. Results Only 1.1% of patients (three) were underweight, whereas 34% were of normal weight, 33% were overweight, and 31.9% were obese. A high percentage of the study population (46.6%) gained excess weight as compared with adequate (26.5%) and inadequate (26.9%) weight gain. The majority of women who were obese before pregnancy (85.7%) gained excess weight during pregnancy. There was a positive correlation between both maternal prepregnancy BMI and gestational weight gain with the neonatal birth weight, but the former showed a stronger correlation (adjusted r2=0.882 for BMI and 0.303 for gestational weight gain). Conclusion Prepregnancy BMI correlates more with neonatal birth weight than with gestational weight gain.