Adolescent BMI Growth: The Role Biological and Non-Biological Mothers in Weight Development

Objectives: Mothers play a pivotal role in adolescent development, but how do the roles of biological and non-biological mothers differ. Using two different model specifications, this study evaluates the differential impacts of biological/non-biological mothers on BMI growth as adolescents age into young adults. Then estimates the BMI growth trajectories of respondents with/without a biological mother.

Methods: Analysis is conducted in three stages using 15 years of data from NLSY97. First, using both a pooled dummy variable OLS and a GLM disaggregated sample specification, this study assesses the impact of biological and non-biological mothers on BMI growth. Next, the samples are divided by age into adolescents and young adults and re-estimated. Finally, multi-level change models including both fixed and random effects estimate the BMI trajectories of adolescent with/without a biological mother.

Results: Results suggest that race/ethnicity, maternal BMI and age are the primary BMI correlates. Lack of significance in the non-biological mother dummy and interaction term in the OLS specification suggests a similar impact for biological/non-biological mothers. However, disaggregate age model shows the impact of non-biological mothers is much smaller than that biological mothers particularly at older ages. As expected, BMI trajectories reveal distinctly different growth for males and females.

Conclusion: Analysis suggests large racial/ethnic and gender differences in BMI growth. Maternal BMI is deterministic irrespective of the mothers’ biological status, but the strength of the relationship varies by age and model specification. The presence/absence of a biological mother in the household shapes the BMI trajectory differently for males and females.