Warning: Some antibiotics have been linked to an increased risk of miscarriage

woman's hand with pills

A new study has highlighted how important it is for women to be super careful about the medications they take, as links are found between a number of common drugs and an increased risk of miscarriage.

Early pregnancy risk

While women who know they are pregnant are usually very vigilant about what they’re ingesting, experts warn that those who may not even realise they are pregnant may be most at risk.

This new Canadian study – just published in the Canadian Medical Association Journal – has detailed some worrying parallels between a few different antibiotics and pregnancy loss.

“Although antibiotics are widely used during pregnancy, evidence regarding their fetal safety remains limited. Our aim was to quantify the association between antibiotic exposure during pregnancy and risk of spontaneous abortion,” study co-author Dr Anick Berard of The Universite de Montreal wrote.

Sketchy details

The research honed-in on data from 9,000 cases of miscarriage in women aged 15 to 45.  

It found that women who miscarried were generally of more advanced maternal age, living alone and suffering from multiple health issues and infections – although all these factors were taken into account by the research team before they reached their findings.

The study concluded there MAY be a link between antibiotic use and these miscarriages, but other factors may be at play, too.

“Residual confounding by severity of infection cannot be ruled out,” the study found.

Benefits and risks

While antibiotics have some real benefits when correctly prescribed, the use of some types of these common drugs were linked to pregnancy loss. Dr Berard explained:

“Infections are prevalent during pregnancy. 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 60 per cent to two-fold increase.”

Which antibiotics have been flagged?

Antibiotics known as macrolides, quinolones, tetracyclines, sulfonamides and metronidazole were flagged as having links to miscarriage. However, the antibiotics erythromycin and nitrofurantoin were researched and found to have no links to miscarriage.

While many of the drugs deemed potentially unsafe for pregnant women by this study are rarely prescribed to expectant mums, they may be prescribed to those who don’t yet realise they are pregnant.

This highlights just how important it is to get the full health picture – including the possibility of pregnancy –  before prescribing these drugs to women of childbearing age. Hopefully this is something your GP is doing already.

There’s obviously much more work to be done to discover more about these links.


If you’re concerned about any medications you are taking – consult your doctor for up-to-date advice.

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