Gonorrhea infection was similar to chlamydia in terms of prior infection increasing risk of subsequent ectopic pregnancy and infertility, Australian researchers found.
Compared with women who tested negative for both infections, women who tested positive for gonorrhea only had a higher risk of ectopic pregnancy (adjusted IRR 1.30, 95% CI 0.87-1.93), while women who tested positive for chlamydia had a similar, slightly higher risk of ectopic pregnancy (aIRR 1.41, 95% CI 1.19-1.66), reported Bette Liu, PhD, of University of New South Wales in Sydney, and colleagues.
Point estimates also suggest that gonorrhea infection (with or without chlamydia infection) and chlamydia infection were each associated with higher risk of tubal infertility, though none of the rate ratios were significant, the authors wrote in Clinical Infectious Diseases.
They noted that both gonorrhea and chlamydia can cause pelvic inflammatory disease, and chlamydia has been shown to cause long-term reproductive problems, such as ectopic pregnancy and infertility. But “the risk associated with gonorrhea is less clear,” they stated.
Researchers examined population-based data from a birth cohort in Western Australia that was comprised of two datasets: birth registrations from 1974 onwards and the 2014 electoral roll. Participants were eligible if they had a birth registration or a record on the electoral roll and were born from 1974 to 1995. Data was linked to, among other things, laboratory chlamydia and gonorrhea test results and death registrations.
More than three-quarters of women testing positive for gonorrhea were Aboriginal women, and they comprised 81% of ectopic pregnancies and all eight tubal infertility cases, though the authors noted that the risk of ectopic pregnancy and tubal infertility did not differ significantly between Aboriginal women versus all women.
Of 314,846 women, 2,763 had an ectopic pregnancy, and of 315,037 women, there were 473 cases of tubal infertility. After adjustment, women who tested positive for both gonorrhea, with or without chlamydia, had a higher rate of ectopic pregnancy compared to women who tested negative for both infections (aIRR 1.10, 95% CI 0.82-1.49).
Examining tubal infertility, risks among women following chlamydia infection (aIRR 1.45, 95% CI 0.95-2.23) were similar as those for women following gonorrhea, with or without chlamydia infections (aIRR 1.38, 95% CI 0.67-2.86). There were not enough women who tested positive for gonorrhea only and had an infertility hospitalization to “reliably estimate risks for this group,” the authors said.
They noted that they were “unaware of any previous longitudinal study examining risks of ectopic pregnancy and infertility following gonorrhea infection,” and characterized their findings that these risks are not substantially greater following gonorrhea versus chlamydia as a “novel” finding.
“Our current findings suggest that the higher risk of clinically severe [pelvic inflammatory disease] following [gonorrhea] compared to chlamydia does not translate to greater risks of the long-term sequelae ectopic pregnancy and infertility,” the authors wrote, adding that a larger sample is needed to confirm these results.
The study was supported by the National Health and Medical Research Council (NHMRC).
Liu and several co-authors disclosed support from NHMRC fellowships.