Objectives: To examine the impact of maintaining or changing shift work status on body mass index (BMI) among female nurses and midwives.
Methods: A longitudinal study. Measurements included day work maintainers, shift work maintainers, day to shift changers and shift to day changers, changes in BMI, and potential confounders selected from baseline survey. Repeated measures analysis of covariance was employed.
Results: The shift to day changers had decreased in BMI over the follow-up period (mean, -3.02; SD, 5.45; P < 0.001). In contrast, the shift work maintainers and the day to shift changers had increased in BMI over follow-up period (mean, 0.56; SD, 5.47; P = 0.01 and mean, 0.13; SD, 5.64; P = 0.04, respectively).
Conclusions: The analysis suggests that shift work could increase BMI.