Chlamydia trachomatis immunoglobulin G3 seropositivity is a predictor of reproductive outcomes in infertile women with patent fallopian tubes

Even in the presence of tubal patency, Chlamydia trachomatis immunoglobulin G3 seropositivity is associated with a lower likelihood of pregnancy and an increased risk of ectopic pregnancy.

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Anne Z. Steiner, M.D., M.P.H., Michael P. Diamond, M.D., Richard S. Legro, M.D., William D. Schlaff, M.D., Kurt T. Barnhart, M.D., M.S.C.E., Peter R. Casson, M.D., Gregory M. Christman, M.D., Ruben Alvero, M.D., Karl R. Hansen, MD, Ph.D., William M. Geisler, M.D., Tracey Thomas, M.P.H., Nanette Santoro, M.D., Heping Zhang, Ph.D., Esther Eisenberg, M.D., M.P.H. for the Reproductive Medicine Network

Volume 104, Issue 6, Pages 1522-1526



To determine if Chlamydia trachomatis (C. trachomatis) seropositivity, as detected by the C. trachomatis elementary body (EB)–based enzyme-linked immunosorbent assay [EB ELISA] predicts pregnancy and pregnancy outcome among infertile women with documented tubal patency.


Cohort study.


Outpatient clinics.


In all, 1,250 infertile women with documented tubal patency enrolled in 1 of 2 randomized controlled trials: Pregnancy in Polycystic Ovary Syndrome II; and the Assessment of Multiple Intrauterine Gestations From Ovarian Stimulation.


Sera were analyzed for anti–C. trachomatis immunoglobulin G (IgG)1 and IgG3 antibodies, using a research C. trachomatis EB ELISA. The optical density (OD)405 readings of ≥0.35 and ≥0.1 were considered positive for IgG1 and IgG3, respectively.

Main Outcome Measure(s):

Primary outcomes included pregnancy, live birth, and ectopic pregnancy. Log-linear regression was used to determine the relative risk after adjusting for age, race, treatment medication, smoking status, and current alcohol use.


A total of 243 (19%) women were seropositive for anti–C. trachomatis IgG3. They tended to be nonwhite and smokers. Anti–C. trachomatis IgG3 seropositive women were significantly less likely to conceive (risk ratio [RR] 0.65, 95% confidence interval [CI] 0.52–0.83) or to have a live birth (RR 0.59, 95% CI 0.43–0.80); these associations were weakened after adjusting for number of hysterosalpingography-documented patent tubes (RR 0.73, 95% CI 0.56–0.97) and (RR 0.73, 95% CI 0.50–1.04), respectively. Anti–C. trachomatis IgG3 seropositive women who conceived had a ×2.7 risk (95% CI 1.40–5.34) of ectopic pregnancy.


Even in the presence of tubal patency, anti–C. trachomatis IgG3 seropositivity is associated with a lower likelihood of pregnancy. Anti–C. trachomatis IgG3 seropositive women have as high as 3 times the risk of ectopic pregnancy.

Clinical Trial Registration Number:

PPCOSII: NCT00719186 and AMIGOS: NCT01044862.

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Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders. The journal publishes juried original scientific articles in clinical and laboratory research relevant to reproductive endocrinology, urology, andrology, physiology, immunology, genetics, contraception, and menopause. Fertility and Sterility® encourages and supports meaningful basic and clinical research, and facilitates and promotes excellence in professional education, in the field of reproductive medicine.