Comparison of menstrual disorders in hospital nursing staff according to shift work pattern

Aim and objective. To assess the association between work in a rotating shift schedule and menstruation characteristics among nurse staff in a prospective study. Background. Rotating shifts have been linked to alterations in the reproductive cycle. In the case of menstrual alterations, the conclusions are not clear. Design. Prospective epidemiological study with follow-up over four months. Method. All the female nurse staff (< 40 years) in a hospital were interviewed, collecting sociodemographic and employment information. They were given a menstrual diary to keep a record of their shifts and characteristics of their menstruation (duration, amount of blood, dysmenorrhoea). They had two types of shifts: (1) Rotating shift schedule (two mornings, two afternoons, one night and two days off) including morning shifts (8:00-15:00), afternoon/evening shifts (15:00-22:00) and night shifts (22:00-8:00), and (2) Day shift schedule including morning shifts (8:00-15:00) and/or afternoon/evening shifts (15:00-22:00). The crude and adjusted odds ratios with 95% confidence interval were calculated using logistic generalised estimating equations (GEE) taking into account the correlations of multiple cycles per worker. Results. One hundred and thirteen workers on the rotating shift and 75 on the day shift participated, and information from 730 menstrual cycles were obtained. There were no differences in prolonged duration, dysmenorrhoea, prolonged duration dysmenorrhoea and excessive bleeding among nurses on rotating shift compared to those on the day shift. For prolonged duration of menstruation, workers with more than five years on the rotating shift showed a slightly lower (nonsignificant) risk compared with those with < 5 years. Conclusions. Nurse staff on the rotating shift did not show increased risk of having menstrual disorders comparing with day staff. Relevance to clinical practice. Shifts with short rotation cycles and a progressive sequence do not appear to cause menstrual disorders in nurse staff who work rotating shifts.