Identifying appropriate pre-pregnancy body mass index classification to improve pregnancy outcomes in women of childbearing age in Beijing, China: a retrospective cohort study.

BACKGROUND AND OBJECTIVES

This study explored the appropriate classification of pre-pregnancy body mass index (BMI) in women of childbearing age in Beijing, China.

METHODS AND STUDY DESIGN

Women with singleton pregnancies at more than 28 gestational weeks were retrospectively reviewed. Based on the pre-pregnancy BMI (kg/m2), these patients were divided into 7 groups: <18.5, >=18.5-22.9, >=23-23.9, >=24-24.9, >=25-27.9, >=28-29.9, and >=30. Pregnancy adverse outcomes, including gestational hypertension with or without preeclampsia, gestational diabetes mellitus, initial cesarean section, postpartum hemorrhage, macrosomia, large-for-gestational age infant and so on were recorded. Binary logistic regression analysis was used to calculate the uncorrected and corrected odds ratios and 95% confidence intervals, with the >=18.5-22.9 group serving as a reference.

RESULTS

A total of 11,136 pregnant women were analyzed. Incidences of above mentioned six adverse outcomes were greater in women with higher pre-pregnancy BMI. The risks of the abovementioned six adverse outcomes were increased significantly among the >=23-23.9, >=24-24.9, >=25-27.9 groups and substantially higher in the >=28-29.9, >=30 groups after correction. <18.5 group showed an increased risk of small-for-gestational age infants.

CONCLUSIONS

For women of childbearing age in Beijing, China, the optimal pre-pregnancy BMI range was >=18.5-22.9 kg/m2, with the cutoff value for overweight status being >=23.0 kg/m2 and the cutoff value for obesity being >=28.0 kg/m2.