No abstract

A matched case-control study of the prevalence of maternal serum anti-chlamydia1 IgG and the relation of such antibodies to ectopic pregnancy was examined.The odds ratio for ectopic pregnancy in patients with chlamydial antibodies compared with those without such antibodies was 3.29, 95 per cent confidence level 1.37-9.07. The attributable risk for ectopic pregnancy in those with chlamydial antibodies was 0.70, but the population attributable risk was only 0.25, 95 per cent confidence level, 0.11439. That is, only 25% of the ectopic pregnancies in the population are related to chlamydia1 antibodies.Serological evidence of maternal chlamydial infection is associated with a tripling of the risk of ectopic pregnancy. The population attributable risk suggests that such infections are associated with only a minority of ectopic pregnancies and offer only a partial explanation for the doubling in the incidence of this condition at our hospital.