Sexually transmitted infections in pregnancy and adverse pregnancy outcomes: A retrospective cohort study

There is a high prevalence and incidence rate of asymptomatic sexually transmitted infections (STIs) during pregnancy in adolescent girls and young women in Africa. The association between STIs and pregnancy outcomes in a hyperepidemic HIV setting has not been well described.

Pregnant women, HIV-1 negative and <28 weeks' gestation at three primary health clinics in KwaZulu-Natal, South Africa were enrolled from February 2017 to March 2018. Vaginal swabs collected at the first and later antenatal visits were stored and retrospectively tested for HSV-2, Trichomonas vaginalis, Chlamydia trachomatis and Neisseria gonorrhoeae at the end of the study. The association between STIs detected at first and later antenatal visits and pregnancy outcome was assessed using multivariable logistic regression models adjusted for maternal age and treatment received for symptomatic STIs.

Testing positive Mycoplasma genitalium at the first antenatal visit was significantly associated with low birth weight (odds ratio [OR] 5.22; 95% confidence interval [CI]: 1.10-15.98). Testing positive for T. vaginalis at the repeat visit was significantly associated with preterm births (OR 2.37; 95% CI: 1.11-5.03), low birth weight (OR 2.56; 1.16-5.63) and a composite adverse pregnancy outcome (OR 2.11; 95% CI: 1.09-4.08). Testing positive for HSV-2 at the repeat visit was also likely associated with experiencing a preterm birth or any adverse pregnancy outcome (OR 3.39; 95% CI: 0.86-13.3) (P = 0.096).

Among predominantly asymptomatic STIs, M. genitalium detected at baseline visit was significantly associated with low birth weight, while T. vaginalis detected at the repeat visit in later pregnancy was significantly associated with preterm birth. Further research is warranted to study the impact of etiological testing of STIs at more than one antenatal visit and empirical treatment on pregnancy outcomes.