Nitrofurantoin in Pregnancy — Is It Safe?
Last reviewed: · Source: US FDA drug label database
Nitrofurantoin is the usual UTI antibiotic through most of pregnancy — but it's avoided from around 36 weeks because of a newborn anaemia risk.
Is it safe to take Nitrofurantoin with Pregnancy?
Nitrofurantoin is first-line for urinary tract infections during most of pregnancy, with decades of reassuring use. The one firm rule: avoid it at term (from about 36 weeks and during labour), because it can trigger haemolytic anaemia in the newborn, whose red blood cells can't yet handle the oxidative stress. If you develop a UTI late in the third trimester, a different antibiotic — often cefalexin — is chosen instead.
How do Nitrofurantoin and Pregnancy interact?
Nitrofurantoin generates reactive oxygen intermediates within bacteria; the same oxidative mechanism can stress red cells deficient in glutathione protection. Neonates have immature erythrocyte enzyme systems (functionally G6PD-low), so drug crossing the placenta near delivery can cause haemolysis.
Data sourced from the US Food and Drug Administration (FDA) drug label database: OpenFDA nitrofurantoin label — neonatal haemolytic anaemia warning at term.
Who should be careful?
Women at 36+ weeks, anyone with known G6PD deficiency, and women whose UTI symptoms include fever or back pain (possible kidney infection — needs urgent review, not just standard tablets).
What if I've already taken Nitrofurantoin and Pregnancy?
Before 36 weeks: no concern — complete the course. At/after 36 weeks: contact your prescriber; the antibiotic will likely be switched and your midwife informed for newborn observation if delivery is imminent.
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Frequently Asked Questions
Is nitrofurantoin safe in pregnancy?
Yes through most of pregnancy — it's the standard UTI treatment. It's avoided from about 36 weeks due to newborn anaemia risk.
Why can't I take it near my due date?
Newborn red blood cells can't neutralise the drug's oxidative effect, risking haemolytic anaemia. A different antibiotic is used at term.
I'm 37 weeks with a UTI — what will I be given?
Usually cefalexin or another pregnancy-suitable alternative guided by your urine culture. Don't leave a UTI untreated at any stage.
Does nitrofurantoin affect breastfeeding?
Small amounts enter milk; it's usually fine except with premature babies or suspected G6PD deficiency. Check with your midwife.