Association of anti-Chlamydia antibodies with ectopic pregnancy in Benin city, Nigeria: a case-control study

Background: Ectopic pregnancy remains a major public health problem especially in many developing countries where it is a significant contributor to pregnancy related morbidity and mortality Objective: To determine the association between prior Chlamydia trachomatis infection and the risk of ectopic pregnancy. Methods: A case-control study from two tertiary health care facilities in Benin City, Nigeria. Ninety eight women with ectopic pregnancy (cases) and another 98 women with uncomplicated intrauterine pregnancy (controls) matched for age, were interviewed using a semi-structured questionnaire and evaluated for serological evidence of prior Chlamydia trachomatis infection. Results: The antibody titres in cases (48%) were significantly higher than in controls (16.3%) (p<0.001). However, the association between Chlamydia antibodies and ectopic pregnancy was attenuated when the effects of indicators of previous pelvic infections, socio-demographic characteristics, contraceptive and sexual history were controlled for. Primary level of education (OR = 6.32; CI, 2.31 - 17.3), three or more lifetime sexual partners (OR = 5.71; CI, 2.39 - 13.65) and prior history of vaginal discharge (OR = 5.00; CI, 2.03 - 12.3) were more likely to be associated with ectopic pregnancy than with the presence of antibodies to Chlamydia trachomatis (OR = 2.82; 95% CI, 1.33 - 5.95). The Population Attributable Risk was 30.9%. Conclusion: Chlamydial infections play only a limited role in the pathogenesis of ectopic pregnancy.