Metronidazole: Trichomoniasis in Pregnancy

• Treatment reduces symptoms and signs of T. vaginalis infection and might reduce transmission. Likelihood of adverse outcomes in women with HIV also is reduced with T. vaginalis therapy

Recommended Regimen

• Metronidazole 2 g orally in a single dose
  OR
• Tinidazole 2 g orally in a single dose

Alternative Regimen 

• Metronidazole 500 mg orally twice a day for 7 days

• The nitroimidazoles are the only class of antimicrobial medications known to be effective against T. vaginalis infections.
• Of these drugs, metronidazole and tinidazole have been cleared by FDA for the oral or parenteral treatment of trichomoniasis

Rationale in Pregnancy

• Pregnancy Category : B. Use of metronidazole for trichomoniasis is contraindicated during the first trimester; the manufacturer makes no further recommendations regarding use during pregnancy
• T. vaginalis infection in pregnant women is associated with adverse pregnancy outcomes, particularly premature rupture of membranes, preterm delivery, and delivery of a low birthweight infant
• Although metronidazole treatment produces parasitologic cure, certain trials have shown no significant difference in perinatal morbidity following metronidazole treatment.
• One trial suggested the possibility of increased preterm delivery in women with T. vaginalis infection who received metronidazole treatment, yet study limitations prevented definitive conclusions regarding the risks of treatment.
• More recent, larger studies have shown no positive or negative association between metronidazole use during pregnancy and adverse outcomes of pregnancy
• If treatment is considered, the recommended regimen in pregnant women is metronidazole 2 g orally in a single dose.
• Symptomatic pregnant women, regardless of pregnancy stage, should be tested and considered for treatment.
• Treatment of T. vaginalis infection can relieve symptoms of vaginal discharge in pregnant women and reduce sexual transmission to partners.
• Although perinatal transmission of trichomoniasis is uncommon, treatment also might prevent respiratory or genital infection of the newborn
• Although metronidazole crosses the placenta, data suggest that it poses a low risk to pregnant women
• No evidence of teratogenicity or mutagenic effects in infants has been found in multiple cross-sectional and cohort studies of pregnant women
• Women can be treated with 2 g metronidazole in a single dose at any stage of pregnancy.

Reference:

1. https://www.cdc.gov/std/tg2015/trichomoniasis.htm
2. https://www.drugs.com/pregnancy/metronidazole.html