China’s capital, Beijing, has recorded unhealthy air pollution levels in past years, with particulate matter (PM) readings exceeding those recommended by the World Health Organisation (WHO). A recent study by a team of researchers from four local universities found that greater exposure to airborne particulate matter, including sulfur dioxide, ozone and carbon monoxide, was associated with a higher risk of missed miscarriage in early pregnancy.

Missed, or silent, miscarriages occur when a foetus dies or stops growing without the mother experiencing any noticeable symptoms, and are often only detected through routine medical check-ups.

In Beijing, the researchers tracked the pregnancies of over 250,000 women, including some 17,490 women who experienced missed miscarriages, using air monitoring stations near the women’s homes and workplaces to gauge their exposure to pollution.

While the risk increase is notably more severe with a higher pollutant concentration, Professor Shaun Brennecke, of the University of Melbourne’s Department of Obstetrics and Gynaecology, said much ethically-fraught lab experimentation would be required before determining a causal link between pollution and miscarriage risk.

Frederica Perera, a professor at Columbia University, also said that the findings are “consistent with other studies of air pollution and pregnancy loss/preterm birth”. The study is therefore hoped to support the Chinese government reduce ambient air pollution.