Maternal prepregnant body mass index and weight gain related to low birth weight in South Carolina.

Objectives: The primary purpose of this study was to describe the proportion of low birth weight that could be potentially prevented by programs focusing on maternal prepregnant body mass index (BMI) and/or weight gain during pregnancy.

Methods: In this historic cohort design, study data consisted of birth certificates linked to the Pregnancy Risk Assessment Monitoring System for South Carolina resident women delivering in South Carolina during 1998 and 1999. Statistical analysis was conducted with the use of chi2, population-attributable risk, and logistic regression. The analysis was performed using SUDAAN to accommodate the analysis weight and extrapolate the sample data to the South Carolina state population.

Results: Eight percent of the very low birth weight (VLBW) rate in South Carolina can be attributed to inadequate weight gain in pregnancy. Approximately 19% of the state's VLBW rate can be attributed to either underweight or overweight BMI at conception. Women with less than adequate weight gain were 1.4 times more likely to deliver a VLBW baby and 1.9 times more likely to deliver a moderately low birth weight baby as compared with women with adequate weight gain.

Conclusions: Appropriate maternal BMI at conception followed by adequate weight gain during pregnancy may have a substantial influence on reducing the number of low birth weight deliveries.