Prepregnancy body mass index is an independent risk factor for gestational hypertension, gestational diabetes, preterm labor, and small- and large-for-gestational-age infants.

OBJECTIVE: We examined if prepregnancy body mass index (BMI) is a risk factor for gestational hypertension, gestational diabetes, preterm labor, and small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants with consideration of gestational weight gain, to document the importance of preconception versus prenatal stage.
METHODS: We used the data of 219 868 women from 2004 to 2011 Pregnancy Risk Assessment Monitoring System (PRAMS). Multivariate logistic regression analyses were performed to examine the effect of prepregnancy BMI for gestational hypertension, gestational diabetes, preterm labor, and SGA and LGA infants with consideration of gestational weight gain.
RESULTS: Regardless of gestational weight gain, women with obese prepregnancy BMI (≥30 kg/m(2)) had increased odds of gestational hypertension (adjusted odds ratios (AOR) = 2.91; 95% CI = 2.76-3.07), gestational diabetes (2.78; 2.60-2.96), and LGA (1.87; 1.76-1.99) compared to women with normal prepregnancy BMI (18.5-24.9 kg/m(2)). Women with underweight prepregnancy BMI (<18.5 kg/m(2)) had increased odds of preterm labor (1.25; 1.16-1.36) and SGA infants (1.36; 1.25-1.49), but decreased odds of LGA infants (0.72; 0.61-0.85) in reference to women with normal prepregnancy BMI (18.5-24.9 kg/m(2)).
CONCLUSIONS: Regardless of adequacy of gestational weight gain, the risk of gestational hypertension, gestational diabetes, and LGA infants increases with obese prepregnancy BMI, whereas that of preterm labor and SGA infants increases with underweight prepregnancy BMI. Preconception care of reproductive aged women is as important as prenatal care to lower the risk of gestational hypertension, gestational diabetes, preterm labor, and SGA and LGA infants.