Risk factors and clinical features of ovarian pregnancy: a case-control study

Objective: To identify risk factors for ovarian pregnancy (OP) and compare clinical features between OP and tubal pregnancy (TP) patients. Design: Case–control study. Setting: University hospital. Participants: A case–control study was conducted from January 2005 to May 2014. Women diagnosed with OP were recruited as the case group (n=71), 145 women with TP and 146 with intrauterine pregnancy (IUP) were matched as controls at a ratio of 1:2:2. Women who refused interviews or provided incomplete information were excluded. Results: OP risk was lower than TP risk in women with serological evidence of Chlamydia trachomatis infection (adjusted OR1 0.17, 95% CI 0.06 to 0.52), previous adnexal surgery (adjusted OR1 0.25, 95% CI 0.07 to 0.95), and current levonorgestrel emergency contraceptive use (adjusted OR1 0.24, 95% CI 0.07 to 0.78). In vitro fertilisation-embryo transfer (IVF-ET) carried a higher risk of OP (adjusted OR1 12.18, 95% CI 2.23 to 66.58) than natural conception. When Controlle...