Placental weight predicts offspring BMI, with diminishing effects over time

A higher placental weight (PW) often results in higher offspring BMI, but its effect lessens by the age of 9 years, reveals a study.

PW positively correlated with offspring BMI (B, 0.005, 95 percent confidence interval [CI], 0.004–0.007) in the final model. This effect, however, diminished over time (age 5 years: B, –0.003, 95 percent CI, –0.006 to –0.001; age 9 years: B, –0.004, 95 percent CI, –0.007 to –0.001). These associations did not differ by sex. 

There was also no significant association with birth weight (BW):PW ratio found with BMI trajectories. Additionally, maternal BMI showed a significant association with offspring BMI gains, specifically at 9 years of age (B, 0.25, 95 percent CI, 0.13–0.38).

“The influence of maternal BMI on offspring BMI at age 9 may reflect the cumulative impact of maternal BMI on offspring BMI trajectories as children approach preadolescence,” the investigators said. 

“Future research should include larger, more diverse populations to better understand these associations,” they added.

In this study, the investigators used linear mixed models to perform a secondary analysis of longitudinal data from 275 mother-child pairs in the Lifeways Cross-Generational Cohort. Mothers provided data on offspring age, height, prepregnancy weight, lifestyle, and education. Prepregnancy BMI was measured.

Hospital records were used to obtain birth outcomes (length, head circumference, gestational age, PW, and BM) and sex. BW:PW ratio was also generated. The investigators measured children’s weight and height at birth, 5-, and 9-year follow-up to calculate BMI. They adjusted for maternal age, education, and smoking as confounders in the final model and used interaction terms to test moderators.