Abstract: Two cluster-randomized controlled trials (RCTs) (involving a total of 5455 women) met the inclusion criteria. The two included trials measured the effectiveness of the intervention in different ways, which meant that meta-analysis of the results was not possible. The overall quality of the two studies, as assessed using the GRADE approach, was low, with high risk of detection and attrition bias in both included trials. One trial (432 women enrolled) conducted in Canada was judged of low methodological quality. This trial did not report on any of the review's pre-specified primary outcomes and the secondary outcomes reported results only as P values. Moreover, losses to follow-up were high (34%, 147 out of 432 women initially enrolled). The authors concluded that prenatal education can effectively change pregnant women's behavior as it increased pet, personal and food hygiene. The second trial conducted in France was also judged of low methodological quality. Losses to follow-up were also high (44.5%, 2233 out of 5023 women initially enrolled) and differential (40% in the intervention group and 52% in the control group). The authors concluded that prenatal education for congenital toxoplasmoses has a significant effect on improving women's knowledge, whereas it has no effect on changing women's behavior. In this trial 17/3949 pregnant women seroconverted for toxoplasmosis: 13/2591 (0.5%) in the intervention group and 4/1358 (0.3%) in the control group. The rate of seroconversion detected during the study did not differ between groups (risk ratio (RR) 1.70, 95% confidence interval (CI) 0.56 to 5.21; participants = 3949; studies = one, low quality evidence). The number of events was too small to reach conclusions about the effect of prenatal education on seroconversion rate during pregnancy. No other randomized trials on the effect of prenatal education on congenital toxoplasmosis rate, or toxoplasmosis seroconversion rate during pregnancy were detected. Even though primary prevention of congenital toxoplasmosis is considered a desirable intervention, given the lack of related risks compared to secondary and tertiary prevention, its effectiveness has not been adequately evaluated. There is very little evidence from RCTs that prenatal education is effective in reducing congenital toxoplasmosis even though evidence from observational studies suggests it is. Given the lack of good evidence supporting prenatal education for congenital toxoplasmosis prevention, further RCTs are needed to confirm any potential benefits and to further quantify the impact of different sets of educational intervention.

Plain-language summary: This review included two randomized controlled trials (involving 5455 women). Data could not be combined because each trial measured effectiveness in different ways. One study was from Canada and involved 432 women randomly assigned to a 10-minute presentation during a prenatal class about toxoplasmosis prevention or to a usual prenatal class. Losses to follow-up were high and 285 completed the post-test questionnaire in the third trimester. Only 5% of the intervention women recalled having obtained information on toxoplasmosis prevention during prenatal classes. However, the authors concluded that prenatal education can effectively change pregnant women's behavior as it increased pet, personal and food hygiene. The other trial conducted in France involved 5023 pregnant women with no evidence of toxoplasmosis infection (seronegative) who were randomly assigned to receive a brochure and an audiotape containing information for toxoplasmosis prevention, or to a usual prenatal class. Losses to follow-up were high and 2790 completed both pre-test and post-test questionnaire on behavior (44.5% loss to follow-up), whereas 3949 women were tested for blood antibodies (22.4% loss to follow-up). Women's behavior did not change after the intervention. Similarly, the seroconversion rate did not differ between groups (13 out of 2591 women seroconverted in the intervention and four out of 1358 in the control group). Both trials were judged as having low methodological quality as assessed by the GRADE approach. This limits our confidence in the results. Evidence supporting prenatal education to prevent congenital toxoplasmosis is therefore limited.