A cross-sectional analysis of the association between night-only or rotating shift work and overweight/obesity among female nurses and midwives

Objective: To examine the associations between shift work types and overweight/obesity among female nurses and midwives.

Methods: A cross-sectional study. Measurement included exposure variables: rotating shift work and night-only shift work; outcome variables: overweight and obesity; and potential confounding and associated variables: modifiable lifestyle factors, general health status, menopausal status, and work pattern.

Results: Among the 2086 participants, almost 60% were overweight/obese (31.7% overweight; 27.1% obese). After we adjusted the selected confounders, we found that rotating shift workers were 1.02 times more likely to be overweight/obese than day workers (P = 0.007; 95% confidence interval [95% CI], 1.004 to 1.03; and P = 0.02; 95% CI: 1.004 to 1.04, respectively). Night-only shift work was found to be significantly associated with obesity only (P = 0.031; relative risk, 1.02; 95% CI, 1.002 to 1.04).

Conclusions: Rotating shift work was associated with both overweight and obesity; and night-only shift work was associated with obesity, not overweight.