The influence of pre-pregnancy BMI and weight gain during pregnancy on pregnancy outcomes

Abstract

Objective: The purpose of this study was to evaluate the association between pre-pregnancy body mass index (BMI) and maternal pregnancy weight gain and pregnancy outcomes. Methods: Ninety-eight pregnant black women were followed up during pregnancy. Pre-pregnancy weight was recorded or calculated by regression analysis, and weekly weight gain was calculated. The correlation between pre-pregnancy BMI, weekly weight gain, blood pressure, and the infants’ birth weight, length and head circumference was assessed, adjusting for gestational age and smoking. Adjustment for HIV status was also done in subjects with known status. Participants were categorised into three groups: pre-pregnancy BMI <19.8, BMI 19.8 - 26, and BMI >26. Results: According to the Institute of Medicine (IOM)’s weight gain recommendations, women in all BMI categories tended to gain excessive weight. Pregnancy weight gain was significantly associated with infant birth weight (χ2=6.25, p=0.04), although no significant correlations were found between weekly weight gain or mothers’ pre-pregnancy BMI, respectively, and birth outcomes. Pre-pregnancy BMI correlated significantly with blood pressure at the second clinic visit. Age and parity correlated significantly with pre-pregnancy BMI; and household income correlated with mothers’ weekly weight gain. Conclusion: Inadequate weight gain was associated with a significantly lower infant birth weight. No correlation was found between infant birth weight and mother’s pre-pregnancy BMI.