Serum antibodies to Chlamydia trachomatis in women with ectopic pregnancy, normal pregnancy or salpingitis.

Serum antichlamydial antibodies were studied in three groups. Group A included 49 women with recent ectopic pregnancy, group B included 56 women with normal first trimester pregnancy, and group C included 20 women with a first episode of acute salpingitis. In the ectopic pregnancy group, a significantly higher percentage of women had IgG antichlamydial antibodies than in the normal pregnancy group (75.5% vs. 46.4%, P less than 0.001). Women with acute salpingitis had the same prevalence of IgG antibodies as patients who had an ectopic pregnancy (60% vs. 75.5%, P less than 0.10). In the ectopic pregnancy group, the women had a significantly higher geometric mean titer (GMT) of antichlamydial IgG antibodies than women with an intra-uterine pregnancy (70.4% vs. 27.3%, P less than 0.001). The results suggest that there is a positive relation between prior Chlamydia trachomatis infection and risk for tubal pregnancy.