The chances of pregnant women suffering a miscarriage can increase as much as 100% if they take antibiotics, a study has revealed.
Published in the Canadian Medical Association Journal and reported by the Royal College of Midwives, a link was found between several classes of antibiotic – including macrolides, quinolones, tetracyclines, sulphonamides and metronidazole – and the likelihood of miscarrying in early pregnancy.
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Researchers found that taking the drugs raised the chances of having a miscarriage by between 60% and 100%. However, nitrofurantoin – often used to treat urinary tract infections in pregnant women – had no effect on miscarriage risk and neither did the widely-used antibiotic erythromycin.
Lead author Dr Anick Bérard said: ‘Although antibiotic use to treat infections has been linked to a decreased risk of prematurity and low birth weight in other studies, our investigation shows that certain types of antibiotics are increasing the risk of spontaneous abortion, with a 60% to two-fold increased risk.
‘The increased risk was not seen for all antibiotics, which is reassuring for users, prescribers and policymakers.’
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Researchers looked at data from almost 9000 cases of miscarriage at an average time of 14 weeks into pregnancy, involving girls and women aged between 15 and 45.