Risk factors for ectopic pregnancy in women with planned pregnancy: a case-control study

To explore the risk factors for ectopic pregnancy (EP) in women with planned pregnancy.

This case-control study was conducted in women with planned pregnancy and included 900 women diagnosed with EP (case group) and 889 women with intrauterine pregnancy (IUP) as the control group matched in terms of age and gestational week. Socio-demographic characteristics, reproductive history, gynecological and surgical history, previous contraceptive use, and history of infertility were compared between the two groups. Blood samples were collected from all the participants to detect serum chlamydia trachomatis (CT) IgG antibody. The odds ratio (OR) with its 95% confidential interval (CI) of each variable was calculated by univariable conditional logistic regression analysis. Factors significantly different between both groups, as revealed by univariable analysis, were entered into a multivariable logistic regression model by stepwise selection.

The risk of EP was associated with previous adnexal surgery (adjusted OR=3.99, 95% CI: 2.40-6.63), uncertainty of previous pelvic inflammatory disease (adjusted OR=6.89, 95% CI: 3.29-14.41), and positive CT IgG serology (adjusted OR=5.26, 95% CI: 3.94-7.04). A history of infertility including tubal infertility (adjusted OR=3.62, 95% CI: 1.52-8.63), non-tubal infertility (adjusted OR=3.34, 95% CI: 1.60-6.93), and in vitro fertilization (IVF) treatment (adjusted OR=5.96, 95% CI: 1.68-21.21) were correlated with the risk of EP. Women who had previously used condoms were less likely to have EP during the current cycle (adjusted OR=0.27, 95% CI: 0.21-0.36).

Besides well-acknowledged risk factors for EP, attention should be paid to women with planned pregnancy who have a history of infertility and/or IVF treatment, to prevent complications from EP.