Certain antibiotics can increase the risk of early miscarriage by up to 100%, a Canadian study has shown.
Researchers at the University of Montreal in Quebec found that some antibiotics raise the chances of spontaneous abortion - miscarriage in the first 20 weeks of pregnancy - by between 60% and 100%. The study looked at almost 9,000 cases of miscarriage in women and girls between the ages of 15 and 45, at an average time of 14 weeks, and accounted for factors such as that women who miscarry tend to be older and experience health issues.
The research has been published in the Canadian Medical Association Journal following a study of pregnancies in Quebec between 1998 and 2009. Antibiotics including macrolides, quinolones, tetracyclines, sulphonamides and metronidazole were all shown to raise the risk of miscarriage, although nitrofurantoin - commonly used to treat urinary tract infections in pregnant women - was not shown to increase the risk.
The drugs found to increase the chance of miscarriage are not routinely prescribed in the UK to women known to be pregnant, highlighting the potential risks facing female patients who don’t realise they are pregnant.