USE OF NITROFURANTOIN IN PREGNANCY

Nitrofurantoin is an antibiotic used for the treatment and prophylaxis of acute or recurrent uncomplicated lower urinary tract infections (UTIs) and pyelitis. It is specifically indicated for the treatment of infections due to susceptible strains of Escherichia coli, Enterococcus, Staphylococcus, Citrobacter, Klebsiella, and Enterobacter.

There is no strong evidence of an association between in utero nitrofurantoin exposure and an overall increased risk of congenital malformation. While individual studies have suggested possible increased risks of hypoplastic left heart, talipes, hypospadias, an/microphthalmia, atrial septal defect, and cleft lip/palate, no pattern of defects is evident, the studies are limited by methodology, and ongoing research is required to confirm or refute these findings. The increase in risk, if any, of congenital malformation following exposure to nitrofurantoin is likely to be small, given that systemic absorption and transfer to the fetus is low.

No statistically significant increased risks of miscarriage, stillbirth, low birth weight, or preterm delivery have been identified, although data are limited for some of these outcomes. An increased incidence of neonatal jaundice has been observed in infants exposed to nitrofurantoin in the month preceding delivery.

Nitrofurantoin in the non-pregnant patient can, in rare cases, cause serious adverse reactions, including peripheral neuropathy, pulmonary toxicity, and fatal hepatic injury. It has also been associated with haemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Nitrofurantoin use is generally avoided during labour and delivery because of the theoretical possibility of haemolytic anaemia in the neonate due to immature erythrocyte enzyme systems.

Guidance on UTI in pregnancy suggests immediate antibiotic treatment, with nitrofurantoin as the recommended first-line option unless contraindicated or not tolerated. Treatment should be reviewed if culture and sensitivity testing of urine sampled before antibiotics were started suggests a more suitable alternative. Any possible risks to the fetus from the drugs used to treat maternal UTI should be weighed against the potential adverse effects for the mother and fetus from an untreated infection. Use of nitrofurantoin near term should be avoided due to a theoretical risk of haemolytic anaemia in the neonate owing to immature erythrocyte enzyme systems.

Exposure to nitrofurantoin at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, other risk factors may be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.