Introduction Abdominal obesity has a high prevalence in the population, which is a risk factor for several health problems. Shift work, especially at night, seems to be associated with this condition.

Objectives This study aimed investigate the relationship between work shift and abdominal obesity in a sample of female shift workers.

Methods A cross-sectional analysis was conducted with 446 female shift workers aged 18–61 years in southern Brazil. Abdominal obesity was identify by measuring waist circumference. The measurements were perform in duplicate and the average of the collected values was consider. A waist circumference equal to or greater than 88 cm was consider abdominal obesity. Multivariate-adjusted associations between work shift and abdominal obesity were assessed by Poisson regression with robust variance.

Results The overall prevalence of abdominal obesity was 44.6% (95% Confidential Interval [95% CI]: 40 to 49.2) and 23.9% (95% CI: 19.9 to 27.8) of the sample were night shift workers. After adjusting for potential confounding factors, night shift women were 38 percent more likely to have abdominal obesity than working women on the day (Prevalence Ratio [PR] = 1.38; 95% CI: 1.12 to 1.70; P = <0.001).

Conclusions This study revealed that work at night has an independent association with abdominal obesity in female shift workers. This finding demonstrates the importance of educational and preventive health actions in the context of public health and occupational health.