The influence of prior oral contraceptive use on risk of endometriosis is conditional on parity

Tu, Frank F., Du, Hongyan, Goldstein, Gregory P., Beaumont, Jennifer L., Zhou, Ying and Brown, Wendy J. (2014) The influence of prior oral contraceptive use on risk of endometriosis is conditional on parity. Fertility and Sterility, 101 6: 1697-1704. doi:10.1016/j.fertnstert.2014.02.014

Author Tu, Frank F.
Du, Hongyan
Goldstein, Gregory P.
Beaumont, Jennifer L.
Zhou, Ying
Brown, Wendy J.
Title The influence of prior oral contraceptive use on risk of endometriosis is conditional on parity
Journal name Fertility and Sterility   Check publisher's open access policy
ISSN 0015-0282
Publication date 2014-06-01
Sub-type Article (original research)
DOI 10.1016/j.fertnstert.2014.02.014
Volume 101
Issue 6
Start page 1697
End page 1704
Total pages 8
Place of publication Philadelphia, PA, United States
Publisher Elsevier
Language eng
Subject 2729 Obstetrics and Gynaecology
2743 Reproductive Medicine
Formatted abstract
Objective To estimate the influence of prior oral contraceptive pill (OCP) use on future diagnosis of endometriosis in young women.
Design Prospective cohort study, the Australian Longitudinal Study on Women's Health.
Setting Community-based sample.
Patient(s) 9,585 women age 18-23 at study onset.
Intervention(s) None.

Main Outcome Measure(s) Risk of self-reported endometriosis estimated with Cox proportional-hazards regression with time-dependent covariates.

Result(s) Compared with never users, endometriosis hazard ratios in nulliparous women with <5 years and ≥5 years of OCP use (preceding diagnosis) were 1.8 (95% CI, 1.30-2.53) and 2.3 (95% CI, 1.59-3.40), respectively. Similar risk was seen in both women reporting infertility and unsure fertility. In parous women with <5 years of use, the hazard ratio for endometriosis was 0.41 (95% CI, 0.15-0.56) and for ≥5 years of use was 0.45 (95% CI, 0.16-1.23). Women reporting early noncontraceptive OCP use had a twofold higher risk (odds ratio 2.07; 95% CI, 1.72-2.51).

Prior OCP exposure reduces the risk of diagnosis of endometriosis in parous women but increases it among nulliparous women; these associations appear unaffected by fertility status. An increased risk of endometriosis diagnosis seen in women reporting early noncontraceptive OCP use may explain some of the positive OCP risk seen in nulliparous women.
Keyword Combined oral contraceptives
Risk factor
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Presented at the 13th World Congress of the International Association for the Study of Pain, August 29–September 2, 2010, Montreal, Quebec, Canada; the 18th Annual Meeting of the International Pelvic Pain Society, Chicago, Illinois, October 21–24, 2010; and the 39th Annual Meeting of the American Association of Gynecologic Laparoscopists (AAGL), November 8–12, 2010; Las Vegas, Nevada.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Human Movement and Nutrition Sciences Publications
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