Gestational weight gain is an important risk factor for excessive fetal growth

To estimate the odds ratio of prepregnant body mass index (BMI), gestational weight gain (GWG), and gestational diabetes mellitus (GDM) for excessive fetal growth, which we define as large for gestational age (LGA).

We included 16,297 women who delivered a live-born singleton baby at term. We fit logistic regressions to estimate the odds ratios of variables, including maternal age, parity, prepregnant BMI ≥23, GWG ≥15 kg, and GDM, for LGA. We classified GWG into four categories (<10, 10-14.9, 15-19.9, and ≥20 kg) and BMI into four categories (underweight, normal, overweight, and obese). After adjusting for age and parity, we analyzed the odds ratios of prepregnant BMI according to GWG between non-GDM and GDM women for LGA.

The odds ratios of GWG ≥15 kg and prepregnancy BMI ≥23 for LGA were 2.40 (95% confidence interval [CI], 2.16-2.67) and 2.24 (95% CI, 1.99-2.51), respectively. The odd ratio of GDM was 1.37 (95% CI, 1.09-1.71). The risk of GDM women with normal/-overweight BMI and GWG <15 kg for LGA was not significantly greater than those of the reference group. The odd ratios of GDM women with overweight/obese BMI and GWG 15 to 19.9 kg were 3.95 (95% CI, 1.26-12.38) and 9.70 (95% CI, 3.79-24.87), respectively.

GWG ≥15 kg might be a more important risk factor for LGA than either prepregnancy BMI ≥23 or GDM. Risk for LGA was highest in obese GDM women with GWG ≥15 kg.