Research press release


Nature Human Behaviour

Health: Small reduction in preterm births during lockdowns in 2020

2020年の新型コロナウイルス感染症(COVID-19)によるロックダウンの最初の3カ月間に、18の高所得国および高中所得国において早産件数の3~4%の減少が見られたことをメタ解析によって明らかにした論文が、Nature Human Behaviourに掲載される。ただし、この研究は早産減少の原因を調べたものではなく、さらなる研究が必要である。


Meghan Azadたちは、2015年1月~2020年7月のカナダ、米国、ブラジル、フィンランド、オーストラリア、英国を含む18カ国の5100万件の出産に関する人口ベースのデータを、26カ国のデータを含む、より広域のメタ解析の一環として収集した。Azadたちは、ロックダウンが実施されなかったと仮定して、予測される周産期転帰を月ごとに推定するモデルを構築し、時間的傾向および季節変化を各国について算出した。その結果、対象国における早産が、モデルの予測と比較して、ロックダウンの最初の2カ月間に4%、またロックダウンの3カ月間に3%減少していたことがわかった。研究グループは、約5万件の早産がロックダウンの最初の1カ月間に回避されていた可能性があるとしている。また、ロックダウンの4カ月目になると変化はみられず、この傾向は極早産(32週までの出産)についても同様であったと述べている。死産率に関するメタ解析では、高所得国における死産率の変化についてのエビデンスは得られなかった。


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.

doi: 10.1038/s41562-023-01522-y


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