Rotating shift work may affect menstrual cycle

April 1, 2011 3:16:50 PM PDT
Women who work rotating shifts may be more likely to experience an irregular menstrual cycle, raising the possibility that work schedules can affect female fertility.

A government study of more than 71,000 U.S. nurses showed those who had worked rotating shifts for at least 20 consecutive months were 23 percent more likely to have irregular menstrual cycles than those working regular or non-rotating shifts.

For the purpose of the study, an "irregular" cycle meant varying by more than a week.

Menstrual irregularities can make it more difficult for a woman to get pregnant.

The study is published in the journal Epidemiology.