The impact of marriage and parenthood on male body mass index: Static and dynamic effects.

RATIONALE: Numerous cross-sectional studies investigated the link between marital status and BMI in the context of competing social science theories (marriage market, marriage selection, marriage protection and social obligation), frequently offering conflicting theoretical predictions and conflicting empirical findings.

OBJECTIVE: This study analysed the effects of marriage, divorce, pregnancy, and parenthood on male BMI in a longitudinal setting, avoiding the estimation bias of cross-sectional studies and allowing for an analysis of BMI fluctuation over time and the dynamic effects of these events.

METHOD: Using the Panel Study of Income Dynamics 1999-2013 dataset (N = 8729), this study was the first to employ a dynamic panel-data estimation to examine the static and dynamic effects of marriage, divorce, and fatherhood on male BMI.

RESULTS: The study showed that married men have higher BMI, but marital status changes largely drove this static effect, namely, an increase in BMI in the period following marriage, and a decrease in BMI preceding and following divorce.

CONCLUSIONS: Thus, this study found marked evidence in support of the marriage market and social obligation theories' predictions about male BMI, and supports neither marriage protection theory nor marriage selection theory. Wives' pregnancies had no significant effect on BMI; instead, men tend to have higher BMI in the periods following childbirth. Finally, analyses showed marked contemporaneous correlations between husband and wife BMI over the course of marriage.