Rotating nightshift work and the risk of endometriosis in premenopausal women

Am J Obstet Gynecol. 2011 Nov;205(5):476.e1-8. doi: 10.1016/j.ajog.2011.06.002. Epub 2011 Jun 12.


Objective: The purpose of this prospective study was to study the association between rotating nightshift work and endometriosis risk within the Nurses' Health Study II.

Study design: We found 89,400 women without diagnosed endometriosis at baseline; the 2062 laparoscopically confirmed cases that were documented during 16 years of follow-up evaluation formed our study population.

Results: Overall, there was no association between rotating nightshift work and risk of endometriosis. When the cases were categorized by infertility status, risk was elevated among women with concurrent infertility and ≥5 years of rotating nightshift work (rate ratio, 1.71; 95% confidence interval, 1.18-2.49; P(trend) = .005), compared with women with no rotating nightshift work. In contrast, there was no association among women without reported infertility (P(heterogeneity) = .003).

Conclusion: Women who work rotating nightshifts for ≥5 years may have a modestly elevated risk of endometriosis if concurrently infertile. However, the relation between shiftwork, endometriosis, and infertility is complex, and the potential for bias because of a healthy or infertile worker effect must be considered.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Circadian Rhythm / physiology
  • Endometriosis / etiology*
  • Female
  • Humans
  • Premenopause
  • Prospective Studies
  • Risk
  • Risk Factors
  • Work
  • Work Schedule Tolerance / physiology*
  • Workplace*