Health: Small reduction in preterm births during lockdowns in 2020 | Nature Human Behaviour | Nature Portfolio

During the first 3 months of COVID-19 lockdowns in 2020, there was a 3–4% reduction in preterm births across 18 high- and upper-middle-income countries, according to a meta-analysis published in Nature Human Behaviour. The study does not investigate the reasons behind these declines and further research is needed.

An estimated 14.8 million preterm births — when a baby is born before 37 weeks — occur annually worldwide, and complications associated with this are a leading cause of infant mortality. Previous research investigating decreases in preterm births during lockdowns has suggested reasons that include a lower risk of infection owing to social distancing, reductions in air pollution, and the possibility that high-risk pregnancies were not addressed with appropriate medical care, resulting in more stillbirths. However, the evidence is not consistent.

Meghan Azad and colleagues collected population-based data on over 51 million births between January 2015 and July 2020 in 18 countries, including Canada, the USA, Brazil, Finland, Australia and the UK, as part of a wider meta-analysis involving data from 26 countries. The authors designed a model to forecast monthly rates of expected perinatal outcomes assuming lockdown had not occurred, accounting for temporal trends and seasonality, for each country. They found that in these countries, preterm births reduced by 4% during the first two months of lockdown, and by 3% in the third month of lockdown, compared to the model projections. They suggest that almost 50,000 preterm births may have been averted during the first month of lockdown. The authors note that no changes were observed for the fourth month of lockdown, and this observation was the same for very preterm births (births before 32 weeks). Their meta-analysis of stillbirth rates did not identify evidence for changes in stillbirth rates in high-income countries.

The authors highlight that their findings do not address the reasons for the reduction in preterm births during the first weeks of lockdown, and they also do not account for the effects of infection with COVID-19 on preterm births. They conclude that further research into the pathways behind these trends is needed to understand the effect of lockdowns on preterm births.