Unsuspected Chlamydia trachomatis infection and in vitro fertilization outcome

Chlamydia trachomatis infections of the female genital tract, although a major cause of infertility, are often asymptomatic and undetected. Since many infertile women now seek in vitro fertilization, a procedure whereby fertilization and embryo implantation are precisely timed, we sought to determine the relation between an unsuspected C. trachomatis infection and the ability of embryos to implant and develop after their transfer to the uterus.

At the time of oocyte aspiration, endocervical samples were obtained from 216 women and assayed by enzyme-linked immunoassay for immunoglobulin A antibodies to C. trachomatis structural membrane components and to recombinant C. trachomatis heat shock protein. The presence of C. trachomatis in the cervices was assessed by the polymerase chain reaction. The outcome of each in vitro fertilization cycle was then ascertained.

Oocytes from 198 (91.7%) of the women were fertilized in vitro and subsequently transferred to the uterus. Term deliveries of healthy infants occurred after 68 (34.3%) of these transfers. Cervical immunoglobulin A antibodies to chlamydial heat shock protein were detected in 5 (7.3%) of the women with term births, and 1 (1.5%) also had immunoglobulin A antibody to chlamydial structural components; 3 (4.4%) were positive by the polymerase chain reaction for C. trachomatis. In contrast, among the 130 women whose embryo transfers did not result in an ongoing pregnancy, 36 (27.7%) had cervical antiheat shock protein immunoglobulin A (p = 0.0007) and 24 (18.5%) had antichlamydial structural component immunoglobulin A (p = 0.0002); 15 (11.5%) of these women had positive results of polymerase chain reaction for C. trachomatis. The majority of women with cervical antibodies to chlamydial structural antigens were also positive for antibody to heat shock protein. However, only 35% of the women with antibodies to heat shock protein were also positive for the other chlamydial antibodies. C. trachomatis was detected by polymerase chain reaction in 29.2% of women with anti-C. trachomatis antibodies and 7.8% of women with anti-heat shock protein antibodies. Women positive for antichlamydial immunoglobulin A were more likely to be undergoing a repeat in vitro fertilization cycle than were women who were antibody negative (p = 0.007).

Unsuspected C. trachomatis infection or reactivation of an immune response to the C. trachomatis heat shock protein may induce an inflammatory reaction in the uterus that impairs embryo implantation and/or facilitates immune rejection after uterine transfer of in vitro fertilized embryos.