Safety and efficacy of praziquantel in pregnant women infected with Schistosoma haematobium in Lambaréné, Gabon – Clinical results from the randomized, single-blinded, controlled freeBILy-Gabon trial

•Praziquantel (PZQ) is well-tolerated in pregnant women with previously known side effects.•PZQ-based treatment in pregnancy shows high efficacy for cure rate and egg reduction rate.•Treatment of urogenital schistosomiasis during pregnancy improves maternal anemia.•PZQ treatment during pregnancy has no impact on the birthweight of newborns.•There were no signs of increased adverse birth outcomes following treatment. Despite evidence of praziquantel's (PZQ) safety for treating schistosomiasis in pregnancy, many countries withhold treatment. Only two randomized controlled trials have investigated PZQ in pregnancy, none involving Schistosoma haematobium. Pregnant women during the second trimester in Lambaréné (Gabon) were screened for S. haematobium infection using urine microscopy and circulating anodic antigen detection. Participants positive for either test were randomized (3:1) to single-dose PZQ 40 mg/kg during pregnancy versus no treatment during pregnancy. Investigators were blinded for allocation. Primary outcomes were reduction of egg (egg reduction rate [ERR]) and antigen production (infection reduction rate [IRR]) while explorative outcomes included assessment of cure rate, adverse events, maternal hemoglobin levels, maternal anemia prevalence at delivery, pregnancy outcomes, and newborn anthropometric parameters. Of 761 women screened 165 were eligible and randomized (intervention n = 124, control n = 41). Of them, 124 completed the study (n = 90 and n = 34, respectively). Treatment led to a significantly higher ERR (95.0% [91-97%] vs 27.0% [−42-63%]) and IRR (95% [91-97%] vs 56% [14-78%]). Common adverse events were dizziness, nausea, and vomiting. Maternal anemia at delivery was significantly lower in the intervention group (odds ratio: 0.40 [0.16;0.96], P = 0.04). No increased risk for adverse pregnancy outcomes was observed. This first randomized controlled trial investigating PZQ in pregnant women with S. haematobium found PZQ to be safe, effective, and reducing maternal anemia. We recommend treating confirmed infections to prevent morbidity in pregnant women.