OBJECTIVE:

The influence of past history of infertility, which is closely associated with reproductive factors, on menopause has not been clarified. The purpose of this study was to clarify the association of reproductive factors, including past history of infertility, with menopause in Japanese women.

STUDY DESIGN:

This study was a cross-sectional analysis of the Japan Nurses' Health Study (JNHS) baseline survey. The JNHS is a nationwide prospective cohort study on the health of Japanese women, and the baseline survey was conducted between 2001 and 2007.

MAIN OUTCOME MEASURE:

We analyzed data for 24,153 pre- and postmenopausal women who were enrolled in the JNHS at the ages 40-59 years. The main outcome measure was menopause.

RESULTS:

Reproductive factors influencing the onset of natural menopause were past history of infertility [relative risk (RR) (age-adjusted odds ratio and 95% confidence interval): 1.28 (1.10-1.48)], past history of endometriosis: 1.32 (1.07-1.64), age at menarche: 0.919 (0.886-0.953) and number of pregnancies: 0.943 (0.911-0.976). Endometriosis as the cause of infertility was significantly associated with earlier onset of menopause (3.43 [2.17-5.44]) after adjustment for age. The strong association of past history of infertility related to endometriosis was still significant after multivariate adjustment.

CONCLUSION:

Menopause in women who have a past history of infertility, especially in those who have suffered from endometriosis, is significantly earlier than that in women without such a history.

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