Pregnancy outcome according to pre-pregnancy body mass index and gestational weight gain.

OBJECTIVE

To assess birth weight in relation to gestational weight gain (GWG) among women who were and were not obese before pregnancy.

METHODS

For a retrospective cohort study, data were obtained for women with a pre-pregnancy body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters) of at least 30 who had a singleton delivery at a center in Denmark in 2010-2011. Data were also obtained for 455 non-obese women (BMI 20.0-24.9). GWG was expressed in absolute terms and relative to published recommendations (11-16kg in non-obese women; 5-9kg in obese women).

RESULTS

A total of 231 obese women were included in analyses. In non-obese and obese women, fetal weight was highest when GWG was above the recommended amount. Among women who had a GWG in line with the recommendations, mean birth weight was higher among those with a pre-pregnancy BMI of 35.0-39.9 (3758±410g) or at least 40 (3671±374g) than among non-obese women (3394±453g; P=0.0058).

CONCLUSION

Birth weight is related to both maternal BMI and GWG. In obese women, adherence to GWG recommendations does not seem to prevent increased birth weights.