Yes, metronidazole can be taken during pregnancy. It is a recommended treatment for bacterial vaginosis (BV) and trichomoniasis in pregnant women, and major health organizations including the CDC endorse its use at any stage of pregnancy. The infections it treats actually pose more risk to your pregnancy than the medication itself.
Why It’s Prescribed During Pregnancy
Metronidazole is most commonly prescribed during pregnancy to treat two conditions: bacterial vaginosis and trichomoniasis. Both are linked to preterm birth and low birth weight, meaning a baby born weighing less than 5.5 pounds. BV is especially common during pregnancy, and leaving it untreated raises the chance of delivering too early.
For trichomoniasis, the CDC recommends that symptomatic pregnant women be tested and treated regardless of what stage of pregnancy they’re in. Metronidazole is the standard treatment for this infection, and there isn’t a widely used alternative. Some experts also recommend screening and treating BV in pregnant women who aren’t showing symptoms but have a higher risk of preterm delivery.
What the Evidence Says About Birth Defects
A meta-analysis pooling data from five studies found no relationship between metronidazole exposure during the first trimester and birth defects. The overall odds ratio was 1.08, with a confidence interval that crossed 1.0, meaning there was no statistically meaningful increase in risk. This is important because the first trimester is the period when organs are forming and medications are most likely to cause problems if they’re going to.
The CDC has also reviewed multiple cross-sectional and cohort studies examining both single-dose and multi-day metronidazole regimens in pregnant women. None found evidence of birth defects or genetic damage in infants. While no medication comes with a guarantee of zero risk, the available data on metronidazole is reassuring, and decades of use in pregnant women haven’t revealed a safety signal.
Oral Tablets vs. Vaginal Gel
Metronidazole comes in two main forms: oral tablets and a vaginal gel. The difference in how much medication reaches your bloodstream is significant. The vaginal gel delivers a peak blood level that’s roughly 2% of what you’d get from a standard oral dose. Total drug exposure over time is about 5% of the oral version. That means far less metronidazole circulates through your body and reaches the baby.
For BV, your provider may offer either form. The vaginal gel is typically applied once or twice daily for five days. For trichomoniasis, oral metronidazole is the standard because the infection isn’t limited to the vaginal area and needs systemic treatment. The CDC recommends 500 mg taken twice daily for seven days, which has been shown to cut reinfection rates in half compared to a single large dose.
Risks of Skipping Treatment
The worry about taking any medication during pregnancy is understandable, but leaving BV or trichomoniasis untreated carries its own risks. BV during pregnancy increases the likelihood of premature delivery. In one large study, a trichomoniasis diagnosis was associated with a 54% higher chance of preterm birth. Treating these infections isn’t just about relieving symptoms like discharge or odor. It’s about protecting the pregnancy itself.
Some trials among women at higher risk for preterm delivery suggest that screening for BV and treating it with oral metronidazole may actually reduce preterm birth. This is why certain experts recommend proactive screening even in women who don’t have noticeable symptoms.
Breastfeeding After Metronidazole
If you’re still taking metronidazole when your baby arrives, or if you need it postpartum, it does pass into breast milk at levels similar to what’s in your blood. Infant blood levels can approach the range used for treating babies directly, which is higher exposure than most mothers would want.
The practical option many nursing mothers use is pumping and discarding milk for the entire course of treatment plus 24 hours after the last dose, feeding the baby stored breast milk or formula during that window. This avoids any meaningful exposure to the infant while still allowing you to complete treatment and resume breastfeeding afterward.