Antenatal Screening for Sexually Transmitted Infections to Reduce Preterm Birth or Low Birthweight (Philani Ndiphile Study): A Randomized Three-Group Trial

SUMMARY Background Chlamydia trachomatis , Neisseria gonorrhoeae , and Trichomonas vaginalis are curable sexually transmitted infections (STIs) associated with adverse birth outcomes. Most infections are asymptomatic. Whether antenatal STI screening improves birth outcomes remains uncertain. Methods In a randomized three-group trial in South Africa, pregnant women aged 18 years or older were assigned before 27 weeks’ gestation to: (1) screening and treatment for Chlamydia trachomatis, Neisseria gonorrhoeae , and Trichomonas vaginalis at enrollment, with tests-of-cure (One-Time Screening); (2) screening and treatment at enrollment, repeated at 30 to 34 weeks (Two-Time Screening); or (3) Standard-of-Care (Syndromic management). The primary outcome was a composite of preterm birth (<37 weeks’ gestation) or low birthweight (<2500 g), analyzed in the modified intention-to-treat population of participants with live births. Components of the composite outcome were evaluated individually as the main secondary outcomes. The study was registered with ClinicalTrials.gov, NCT04446611 . Findings Of 2247 enrolled participants, 1910 had live births. The composite outcome occurred in 22·9% of the One-Time Screening group (risk ratio [RR] 0·99; 95% confidence interval [CI] 0·81–1·21), 20·6% of the Two-Time Screening group (RR 0·89; 95% CI 0·72–1·09), compared with 23·2% of the Standard-of-Care group. Preterm birth occurred in 18·9% of the One-Time Screening group (RR 1·00; 95% CI 0·80–1·26), 14·5% of the Two-Time Screening group (RR 0·77; 95% CI 0·60–0·99), and 18·8% of the Standard-of-Care group. Low birthweight occurred in 14·1% of the One-Time Screening group (RR 1·10; 95% CI 0·83–1·46), 12·9% of the Two-Time Screening group (RR 1·01; 95% CI 0·76–1·35), and 12·8% of the Standard-of-Care group. Interpretation Neither screening strategy for Chlamydia trachomatis , Neisseria gonorrhoeae , and Trichomonas vaginalis reduced the primary composite outcome of preterm birth or low birthweight, or low birthweight alone. The Two-Time antenatal STI screening strategy, however, reduced preterm birth by 23%.