It seems to come up about once or twice a month about the safety of metronidazole in pregnancy.This has been very controversial over the years, but the current stance is that it is safe in pregnancy.In fact, untreated vaginal infections, bacterial vaginosis and trichomonas, have been associated with miscarriages and preterm labor, so the benefits outweigh the risks.
Below are two good references to add to your file in case you get into a debate with somebody quoting old data.
Safety of metronidazole during pregnancy: a cohort study of risk of congenital abnormalities, preterm delivery and low birth weight in 124 women. J Antimicrob Chemother 1999; 44: 854-855 http://jac.oxfordjournals.org/cgi/content/full/44/6/854
