Job strain and changes in the body mass index among working women: a prospective study

Objectives The relationship between job strain and weight gain has been unclear, especially for women. Using data from over 52 000 working women, we compare the association between change in job strain and change in BMI across different levels of baseline BMI. Subjects/Methods We used data from participants in the Nurses’ Health Study II (n=52 656, mean age = 38.4), an ongoing prospective cohort study. Using linear regression, we modeled the change in BMI over 4 years as a function of the change in job strain, baseline BMI, and the interaction between the two. Change in job strain was characterized in four categories combining baseline and follow-up levels: consistently low strain [low at both points], decreased strain [high strain at baseline only], increased strain [high strain at follow-up only], and consistently high strain [high at both points]. Age, race/ethnicity, pregnancy history, job types, and health behaviors at baseline were controlled for in the model. Results In adjusted models, women who reported high job strain at least once during the four-year period had a greater increase in BMI (ΔBMI=0.06–0.12, p