Preterm birth, stillbirth and early neonatal mortality during the Danish COVID-19 lockdown

  1. Paula L. Hedley
  2. Gitte Hedermann
  3. Christian M. Hagen
  4. Marie Bækvad-Hansen
  5. Henrik Hjalgrim
  6. Klaus Rostgaard
  7. Anna D. Laksafoss
  8. Steen Hoffmann
  9. Jørgen Skov Jensen
  10. Morten Breindahl
  11. Mads Melbye
  12. Anders Hviid
  13. David M. Hougaard
  14. Lone Krebs
  15. Ulrik Lausten-Thomsen
  16. Michael Christiansen

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Abstract

Using provisional or opportunistic data, three nationwide studies (The Netherlands, the USA and Denmark) have identified a reduction in preterm or extremely preterm births during periods of COVID-19 restrictions. However, none of the studies accounted for perinatal deaths. To determine whether the reduction in extremely preterm births, observed in Denmark during the COVID-19 lockdown, could be the result of an increase in perinatal deaths and to assess the impact of extended COVID-19 restrictions, we performed a nationwide Danish register-based prevalence proportion study. We examined all singleton pregnancies delivered in Denmark during the COVID-19 strict lockdown calendar periods (March 12–April 14, 2015-2020, N  = 31,164 births) and the extended calendar periods of COVID-19 restrictions (February 27–September 30, 2015-2020, N  = 214,862 births). The extremely preterm birth rate was reduced (OR 0.27, 95% CI 0.07 to 0.86) during the strict lockdown period in 2020, while perinatal mortality was not significantly different. During the extended period of restrictions in 2020, the extremely preterm birth rate was marginally reduced, and a significant reduction in the stillbirth rate (OR 0.69, 0.50 to 0.95) was observed. No changes in early neonatal mortality rates were found.

Conclusion : Stillbirth and extremely preterm birth rates were reduced in Denmark during the period of COVID-19 restrictions and lockdown, respectively, suggesting that aspects of these containment and control measures confer an element of protection. The present observational study does not allow for causal inference; however, the results support the design of studies to ascertain whether behavioural or social changes for pregnant women may improve pregnancy outcomes.

What is Known: • The aetiologies of preterm birth and stillbirth are multifaceted and linked to a wide range of socio-demographic, medical, obstetric, foetal, psychosocial and environmental factors. • The COVID-19 lockdown saw a reduction in extremely preterm births in Denmark and other high-income countries. An urgent question is whether this reduction can be explained by increased perinatal mortality.
What is New: • The reduction in extremely preterm births during the Danish COVID-19 lockdown was not a consequence of increased perinatal mortality, which remained unchanged during this period. • The stillbirth rate was reduced throughout the extended period of COVID-19 restrictions.

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  1. Version published to 10.1007/s00431-021-04297-4
  2. ScreenIT

    SciScore for 10.1101/2021.06.09.21258622: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Ethicsnot detected.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • No funding statement was detected.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

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  3. Version published to 10.1101/2021.06.09.21258622v1 on medRxiv