Racial differences in contribution of prepregnancy obesity and excessive gestational weight gain to large-for-gestational-age neonates

Abstract
Objectives
To examine the racial differences in the population attributable fraction (PAF) of prepregnancy obesity and excessive gestational weight gain to large-for-gestational-age (LGA) neonates.

Methods
We conducted a population-based retrospective cohort study among all women who had prenatal screening and had a singleton live birth in a hospital (1 April 2016–31 March 2017) using data from Ontario birth registry in Canada. We used multivariable log-binomial regression models to estimate the PAF and 95% confidence interval (CI) of LGA neonates due to prepregnancy obesity and excessive gestational weight gain. All models were stratified by race (White, Asian, and Black).

Results
Of the 74,402 eligible women, the prevalence of prepregnancy obesity, excessive gestational weight gain, and LGA neonate was 21.1%, 60.0%, and 11.3%, respectively, for Whites; 9.3%, 45.9%, and 5.4%, respectively, for Asians; and 28.6%, 52.4%, and 7.9%, respectively, for Blacks. The association of prepregnancy obesity was greater than that of excessive gestational weight gain on LGA for all racial groups. Excessive gestational weight gain contributed more than prepregnancy obesity in Whites (PAF 32.9%, 95% CI [30.3–35.5%] and 16.6%, 95% CI [15.3–17.9%], respectively, for excessive gestational weight gain and prepregnancy obesity) and in Asians (PAF 32.1%, 95% CI [27.2–36.7%] and 11.8%, 95% CI [9.5–14.1%], respectively, for excessive gestational weight gain and prepregnancy obesity). Prepregnancy obesity (PAF 22.8%, 95% CI [17.1–28.1%]) and excessive gestational weight gain (PAF 20.1%, 95% CI [4.7–33.0%]) contributed to LGA neonates almost the same in Blacks.

Conclusions
Excessive gestational weight gain contributed more to LGA neonates than prepregnancy obesity in Whites and Asians, while there was no difference between excessive gestational weight gain and prepregnancy obesity in their contributions to the LGA neonates in Blacks. The differences are mostly driven by the differential prevalence of the two risk factors across racial groups.