Mycoplasma genitalium infection and adverse pregnancy outcomes among pregnant women in South Africa: prospective cohort study

Background: Sexually transmitted infections (STIs) and vaginal dysbiosis during pregnancy are associated with adverse pregnancy outcomes. Mycoplasma genitalium is the most recent STI implicated but evidence remains limited. The objectives of this study were to investigate 1) the association between M. genitalium infection during pregnancy and gestational age at delivery, preterm birth, miscarriage or stillbirth, and low birth weight and 2) the interaction with vaginal dysbiosis. Methods: We conducted a prospective cohort study in East London, South Africa. We enrolled pregnant women at gestational age <27 weeks, confirmed by ultrasound. We tested vaginal samples using nucleic acid amplification tests for M. genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, other genital mycoplasmas and Candida spp. We defined vaginal dysbiosis using Gram-stain criteria as a Nugent score 4-10. We used quantile regression to compare the outcome in women with and without M. genitalium across the gestational age distribution, adjusting for prespecified sociodemographic and clinical characteristics and co-occurring organisms. Results: From April 1, 2021 to August 29, 2023, we enrolled 603 women, followed up 584 and obtained pregnancy outcomes for 560 (93%). Median age was 28 years (interquartile range, IQR 24, 33) and 27% of women were living with HIV. M. genitalium was detected in 44/584 (8%, 95% CI 6, 10%) and vaginal dysbiosis in 375/584 (64%) of women. Median gestational age at delivery was 39 weeks +0 days (IQR 37+4, 40+1) in women with and 39 weeks +0 days (37+4, 40+0) in those without M. genitalium. In multivariable models, associations were not observed for any adverse birth outcomes. There was no interaction between M. genitalium and vaginal dysbiosis. Discussion: M. genitalium in pregnancy was not associated with earlier gestational age at delivery or with other adverse birth outcomes. These findings do not support routine testing and treatment for M. genitalium in pregnancy.