Most antibiotics during pregnancy are unlikely to cause neurological damage to fetuses

The majority of antibiotics prescribed during pregnancy do not increase the risk of term babies being born with epilepsy or cerebral palsy finds research by teams at the UCL Institute of Child Health, research partner of Great Ormond Street Hospital. 

While the finding, published in PLOS ONE, should provide reassurance to expectant mothers that antibiotic treatment during pregnancy is unlikely to harm their unborn baby, the work also highlights that a class of antibiotics known as macrolides — which are currently considered safe — may carry a small risk and so should be reviewed by the Medicines regulator.  

One-third of pregnant woman in the UK are prescribed antibiotics in order to treat bacterial infections, such as cystitis and some respiratory tract infections. These prenatally prescribed antibiotics are often needed to treat the mother and prevent infections from causing damage to the baby.

Current guidelines for expectant mothers state that most antibiotics are safe to take but the research team wanted to find out whether any types of antibiotics were for were associated with neurological damage in the fetus. The team studied nearly 196,000 mothers who gave birth to single children born at term (37 weeks onwards) between 1990 and 2010 and who were prescribed antibiotics by their GP during pregnancy. Two-thirds of the mothers prescribed antibiotics were given a type of penicillin, while 7% were prescribed macrolides. They followed up children using GP records to find out whether those who developed cerebral palsy or epilepsy were more likely to have been born to mothers who were prescribed certain types of antibiotics.

While most recommended antibiotics were found not to harm fetuses, the researchers found an increase in the number of children who developed cerebral palsy or epilepsy when mothers were prescribed macrolides instead of penicillin antibiotics – two antibiotics considered safe during pregnancy.  This increased risk is still relatively small though and for every 153 women treated with a macrolide instead of a penicillin antibiotic, there will be one additional case of cerebral palsy and/or epilepsy.

Ruth Gilbert, Professor of Clinical Epidemiology at the Institute of Child Health and honorary GOSH consultant who co-authored the study says, ‘The message for pregnant women is that they should not stop taking antibiotics when they are prescribed them for infection. Most antibiotics in pregnancy are not harmful to their child and can be very effective at reducing serious fetal damage due to infection. ‘

Our study adds to evidence from several studies over the last 10 years which have reported rare but harmful effects associated with macrolide antibiotics and so we recommend that the use of macrolides such as erythromycin during pregnancy should be reviewed by the Medicines regulator and reconsidered in national guidelines.’