Background

Although some studies have reported a decrease in preterm birth following the start of the COVID-19 pandemic, the findings are inconsistent.

Objective

This study aimed to compare the incidences of preterm birth before and after the introduction of COVID-19 mitigation measures in Scandinavian countries using robust population-based registry data.

Study Design

This was a registry-based difference-in-differences study using births from January 2014 through December 2020 in Norway, Sweden, and Denmark. The changes in the preterm birth (<37 weeks) rates before and after the introduction of COVID-19 mitigation measures (set to March 12, 2020) were compared with the changes in preterm birth before and after March 12 from 2014 to 2019. The differences per 1000 births were calculated for 2-, 4-, 8-, 12-, and 16-week intervals before and after March 12. The secondary analyses included medically indicated preterm birth, spontaneous preterm birth, and very preterm (<32 weeks) birth.

Results

A total of 1,519,521 births were included in this study. During the study period, 5.6% of the births were preterm in Norway and Sweden, and 5.7% were preterm in Denmark. There was a seasonal variation in the incidence of preterm birth, with the highest incidence during winter. In all the 3 countries, there was a slight overall decline in preterm births from 2014 to 2020. There was no consistent evidence of a change in the preterm birth rates following the introduction of COVID-19 mitigation measures, with difference-in-differences estimates ranging from 3.7 per 1000 births (95% confidence interval, −3.8 to 11.1) for the first 2 weeks after March 12, 2020, to −1.8 per 1000 births (95% confidence interval, −4.6 to 1.1) in the 16 weeks after March 12, 2020. Similarly, there was no evidence of an impact on medically indicated preterm birth, spontaneous preterm birth, or very preterm birth.

Conclusion

Using high-quality national data on births in 3 Scandinavian countries, each of which implemented different approaches to address the pandemic, there was no evidence of a decline in preterm births following the introduction of COVID-19 mitigation measures.

中文翻译：

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挪威、瑞典和丹麦采用 COVID-19 缓解措施后的早产：一项基于注册的差异研究

背景

尽管一些研究报告称，在 COVID-19 大流行开始后早产率有所下降，但研究结果并不一致。

客观的

本研究旨在使用基于人群的可靠登记数据，比较斯堪的纳维亚国家实施 COVID-19 缓解措施前后的早产发生率。

学习规划

This was a registry-based difference-in-differences study using births from January 2014 through December 2020 in Norway, Sweden, and Denmark. The changes in the preterm birth (<37 weeks) rates before and after the introduction of COVID-19 mitigation measures (set to March 12, 2020) were compared with the changes in preterm birth before and after March 12 from 2014 to 2019. The differences per 1000 births were calculated for 2-, 4-, 8-, 12-, and 16-week intervals before and after March 12. The secondary analyses included medically indicated preterm birth, spontaneous preterm birth, and very preterm (<32 weeks) birth.

Results

本研究共纳入 1,519,521 例新生儿。在研究期间，挪威和瑞典有 5.6% 的早产儿，丹麦有 5.7% 的早产儿。早产的发生率存在季节性变化，冬季发生率最高。在这 3 个国家中，从 2014 年到 2020 年，早产率总体上略有下降。没有一致的证据表明在引入 COVID-19 缓解措施后早产率发生了变化，估计值存在差异从 2020 年 3 月 12 日后的前两周每 1000 名新生儿中有 3.7 例（95% 置信区间，-3.8 至 11.1），到 2020 年 3 月 12 日之后的 16 周内每 1000 名新生儿中有 -1.8 例（95% 置信区间，-4.6 至 1.1） 2020 年 3 月 12 日。同样，没有证据表明对有医学指征的早产有影响，

结论

使用 3 个斯堪的纳维亚国家的高质量国家出生数据，每个国家都采用不同的方法来应对这一流行病，没有证据表明在采取 COVID-19 缓解措施后早产率有所下降。