Study	Reason for exclusion
Robinson 1965	This trial was excluded because it was not clear whether the comparisons had been made between randomized groups. The authors extended a series of metronidazole treated pregnant and nonpregnant women to include a group of women randomly allocated to a treatment and placebo. Consequently, there is an imbalance in the sample sizes of 2 groups and it is not possible to identify randomized groups in the tables presented.
Roos 1978	There was no randomized comparison.
Kigozi 2003	This study is excluded as it is a secondary analysis of a randomized trial designed for evaluation of interventions for STD control for prevention of HIV. In this trial the intervention was a community‐based trial of presumptive treatment of several antimicrobials including metronidazole as antitrichomoniasis agent. Therefore, to receive the treatment (or no treatment) the women were not required to have trichomoniasis in pregnancy. Also, the authors have acknowledged that some women in the intervention arm were likely to have received (presumptive) treatment before pregnancy.
Stringer 2010	The trial is a secondary analysis of a randomized trial where the main comparison is the use of several antenatal and intrapartum antibiotics for reduction of chorioamnionitis‐related perinatal HIV transmission against no use of antibiotics.

HIV: human immunodeficiency virus

STD: sexually transmitted disease