Objective: To evaluate the impact of screening and treating asymptomatic pregnant women for Chlamydia (C.) trachomatis and Neisseria (N.) gonorrhoeae infections on the frequency of preterm birth or low birthweight infants in Botswana.

Design: Non-randomised, cluster-controlled trial.

Setting: Four antenatal care clinics in Gaborone, Botswana.

Population: Pregnant women aged ≥15 years, attending a first antenatal care visit, ≤27 weeks of gestation and without urogenital symptoms were eligible.

Methods: Participants in the intervention clinics received screening (GeneXpert®, Cepheid) during pregnancy and at the postnatal visit. Participants in the standard-of-care clinics received screening at the postnatal visit only. We used multivariable logistic regression and post-estimation predictive margins analysis. Post-hoc analysis was conducted among sub-samples stratified by parity.

Main outcome measures: Preterm birth (<37 weeks of gestation) and low birthweight (<2500 g).

Results: After controlling for parity, hypertension, antenatal care visits and clinic site, the predicted prevalence of preterm birth or low birthweight was lower in the intervention arm (11%) compared with the standard-of-care arm (16%) (adjusted odds ratio [aOR] 0.59; 95% confidence interval [CI] 0.28-1.24). In post-hoc analysis, the intervention was more effective than the standard-of-care (aOR 0.20; 95% CI 0.07-0.64) among nulliparous participants.

Conclusion: A C. trachomatis and N. gonorrhoeae infection screening and treatment intervention among asymptomatic pregnant women may have reduced preterm birth or low birthweight outcomes, but results were not statistically significant. Post-hoc analysis found that the intervention reduced adverse outcomes among nulliparous participants.

Keywords: Chlamydia trachomatis; Neisseria gonorrhoeae; low birthweight; pregnancy; preterm birth; sexually transmitted infections; syndromic management.