PLoS ONE (Jan 2014)

Contraceptive Use and the Risk of Ectopic Pregnancy: A Multi-Center Case-Control Study.

  • Cheng Li,
  • Wei-Hong Zhao,
  • Chun-Xia Meng,
  • Hua Ping,
  • Guo-Juan Qin,
  • Shu-Jun Cao,
  • Xiaowei Xi,
  • Qian Zhu,
  • Xiao-Cui Li,
  • Jian Zhang

DOI
https://doi.org/10.1371/journal.pone.0115031
Journal volume & issue
Vol. 9, no. 12
p. e115031

Abstract

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OBJECTIVE:To evaluate the association between the risk of ectopic pregnancy (EP) and the use of common contraceptives during the previous and current conception/menstrual cycle. METHODS:A multi-center case-control study was conducted in Shanghai. Women diagnosed with EP were recruited as the case group (n = 2,411). Women with intrauterine pregnancy (IUP) (n = 2,416) and non-pregnant women (n = 2,419) were matched as controls at a ratio of 1∶1. Information regarding the previous and current use of contraceptives was collected. Multivariate logistic regression analyses were performed to calculate odds ratios (ORs) and the corresponding 95% confidential intervals (CIs). RESULTS:Previous use of intrauterine devices (IUDs) was associated with a slight risk of ectopic pregnancy (AOR1 = 1.87 [95% CI: 1.48-2.37]; AOR2 = 1.84 [1.49-2.27]), and the risk increased with the duration of previous use (P1 for trend <10-4, P2 for trend <10-4). The current use of most contraceptives reduced the risk of both unwanted IUP (condom: AOR = 0.04 [0.03-0.05]; withdrawal method: AOR = 0.10 [0.07-0.13]; calendar rhythm method: AOR = 0.54 [0.40-0.73]; oral contraceptive pills [OCPs]: AOR = 0.03 [0.02-0.08]; levonorgestrel emergency contraception [LNG-EC]: AOR = 0.22 [0.16-0.30]; IUDs: AOR = 0.01 [0.005-0.012]; tubal sterilization: AOR = 0.01 [0.001-0.022]) and unwanted EP (condom: AOR1 = 0.05 [0.04-0.06]; withdrawal method: AOR1 = 0.13 [0.09-0.19]; calendar rhythm method: AOR1 = 0.66 [0.48-0.91]; OCPs: AOR1 = 0.14 [0.07-0.26]; IUDs: AOR1 = 0.17 [0.13-0.22]; tubal sterilization: AOR1 = 0.04 [0.02-0.08]). However, when contraception failed and pregnancy occurred, current use of OCPs (AOR2 = 4.06 [1.64-10.07]), LNG-EC (AOR2 = 4.87 [3.88-6.10]), IUDs (AOR2 = 21.08 [13.44-33.07]), and tubal sterilization (AOR2 = 7.68 [1.69-34.80]) increased the risk of EP compared with the non-use of contraceptives. CONCLUSION:Current use of most contraceptives reduce the risk of both IUP and EP. However, if the contraceptive method fails, the proportions of EP may be higher than those of non-users. In the case of contraceptive failure in the current cycle, EP cases should be differentiated according to current use of OCPs, LNG-EC, IUDs, and tubal sterilization. In addition, attention should be paid to women with previous long-term use of IUDs.