A systematic review and meta-analysis was performed comparing women who worked the day shift (hours between 8:00 AM and 6:00 PM) with women who worked outside of that time frame. Reproductive outcomes included change of cycle length to less than 25 days or more than 31 days, infertility, and spontaneous pregnancy loss, before 25 weeks gestation. Sixteen independent cohorts were found to best address the question of impact of shift work on reproductive outcomes. Cycle length changes occurred in 16%, vs 13% of controls, giving an odds ratio of 1.22. Infertility increased in shift workers, with an odds ratio of 1.8 (11.3% vs 9.9%), but lost significance after adjusting for confounders. Working the night shift, but not the evening shift, was associated with early spontaneous pregnancy loss, with an adjusted OR of 1.41.
The authors concluded that this was not strong enough evidence to recommend women of reproductive years to avoid shift work, and even if they have one of these outcomes, there are many other causes, so shift work may not be to blame.
An advantage of RRM is women charting have such a great record of their reproductive health, and their specific changes can be noted before and after starting night shift. It becomes a good tool for discussion and assessing effects of different stressors. If a woman does become pregnant, and cannot change her working hours, encourage her to continue charting. Often pregnancy stressors will present with a change in her baseline pregnant pattern, and increased fertile type mucus, or spotting, can alert her to contact her physician for further evaluation, such as progesterone and estrogen level assessment.
What do you think? If you have a patient who does shift work and presents with irregular menses, infertility or miscarriage, what do you recommend?
View the Article:
Stocker LJ, Macklon NS, Cheong YC, Bewley SJ. Influence of shift work on early reproductive outcomes: a systematic review and meta-analysis. Obstet Gynecol. 2014 Jul;124(1):99-110. doi: 10.1097. Review. PMID: 24901274