Association of trimester-specific gestational weight gain with child BMI by maternal BMI categories

TL;DR

This study shows that gaining more weight during the first and second trimesters of pregnancy is linked to higher BMI in children at age 5, especially for mothers of normal weight or overweight.

Contribution

The study identifies trimester-specific gestational weight gain effects on child BMI across maternal BMI categories.

Findings

Higher total gestational weight gain was linearly associated with increased child BMI at 5 years.

First and second trimester weight gain showed stronger associations with child BMI z-scores than third trimester.

Associations were less significant in mothers with higher obesity classes.

Abstract

Background/Objectives:
Information is lacking about how trimester-specific gestational weight gain (GWG) is associated with childhood body mass index (BMI) across maternal BMI categories.
Subjects/Methods:
We examined the association between GWG and child BMI in patients served by a national network of community health care organizations. We stratified by pre-pregnancy BMI (n=5721 normal weight; 5667 overweight; 3213 obesity class I; 1344 class II; 692 class III). Child BMI z-score and overweight and obesity status at age 5 were modeled as a function of total GWG and GWG rate in each trimester, controlling for GWG rate in previous trimester(s) and maternal characteristics, using modified Poisson regression.
Results:
Higher total GWG during pregnancy was positively associated with child BMI at 5 years of age in a linear, dose-dependent manner. When examined by trimester of pregnancy, a 1 kg/week in the first trimester was associated with a 0.24 to 0.42 increase in child BMI z-score. The same increase in the second trimester was associated with a 0.30 to 0.53 increase in child BMI z-score, although the associations were not significant in class II and III obesity classes. Associations between GWG in the third trimester and child BMI z-score were weak (0.12 to 0.21 increase in BMI z-score per kg/week increase in maternal weight) and not significant.
Conclusion:
Among a diverse and underserved pregnant population, GWG in the 1
st
and 2
nd
trimesters are most strongly associated with child BMI at age 5. Early pregnancy and mid-pregnancy may be key times to intervene to prevent overweight and obesity in offspring.