Limited Effects of SARS-CoV-2 Pandemic-related Lockdowns and Reduced Population Mobility on Preterm Birth Rates: A Secondary Analysis of Bavarian Obstetric Quality Parameters from 2010 to 2020

Abstract

Introduction International studies on preterm birth rates during COVID-19 lockdowns report different results. This study examines preterm birth rates during lockdown periods and the impact of the mobility changes of the population in Bavaria, Germany.

Material and Methods This is a secondary analysis of centrally collected data on preterm births in Bavaria from 2010 to 2020. Preterm births (< 37 weeks) in singleton and twin pregnancies during two lockdowns were compared with corresponding periods in 2010 – 2019. Fisherʼs exact test was used to compare raw prevalence between groups. Potential effects of two fixed lockdown periods and of variable changes in population mobility on preterm birth rates in 2020 were examined using additive logistic regression models, adjusting for long-term and seasonal trends.

Results Unadjusted preterm birth rates in 2020 were significantly lower for singleton pregnancies during the two lockdown periods (Lockdown 1: 5.71% vs. 6.41%; OR 0.88; p < 0.001; Lockdown 2: 5.71% vs. 6.60%; OR = 0.86; p < 0.001). However, these effects could not be confirmed after adjusting for long-term trends (Lockdown 1: adj. OR = 0.99; p = 0.73; Lockdown 2: adj. OR = 0.96; p = 0.24). For twin pregnancies, differences during lockdown were less marked (Lockdown 1: 52.99% vs. 56.26%; OR = 0.88; p = 0.15; Lockdown 2: 58.06% vs. 58.91%; OR = 0.97; p = 0.70). Reduced population mobility had no significant impact on preterm birth rates in singleton pregnancies (p = 0.14) but did have an impact on twin pregnancies (p = 0.02).

Conclusions Reduced preterm birth rates during both lockdown periods in 2020 were observed for singleton and twin pregnancies. However, these effects are reduced when adjusting for long-term and seasonal trends. Reduced population mobility was associated with lower preterm birth rates in twin pregnancies.

Zusammenfassung

Einleitung Internationale Studien zu Frühgeburtenraten während den COVID-19-Lockdowns kommen zu unterschiedlichen Ergebnissen. Diese Studie untersucht die Frühgeburtenraten während den Lockdowns sowie die Auswirkungen von Änderungen der Bevölkerungsmobilität in Bayern auf die Frühgeburtenraten.

Material und Methoden Es handelt sich um eine Sekundäranalyse von zentral erhobenen Daten zu Frühgeburten in Bayern zwischen 2010 und 2020. Die Frühgeburten (< 37. Schwangerschaftswoche) bei Einlings- und Zwillingsschwangerschaften, die in der Zeit der beiden Lockdowns auftraten, wurden den Frühgeburten in den Vergleichszeiträume der Jahre 2010 – 2019 gegenübergestellt. Die Rohprävalenzen der Gruppen wurden mit dem exakten Test nach Fisher verglichen. Additive logistische Regressionsmodelle wurden eingesetzt, um die potenziellen Auswirkungen von 2 Lockdowns sowie von Änderungen der Bevölkerungsmobilität auf die Frühgeburtenraten im Jahre 2020 zu untersuchen. Die Effekte wurden dann zusätzlich auf langfristige und saisonbedingte Trends adjustiert.

Ergebnisse Die unbereinigten Frühgeburtenraten von Einlingsschwangerschaften während den 2 Lockdowns im Jahre 2020 waren signifikant niedriger (Lockdown 1: 5,71% vs. 6,41%; OR 0,88; p < 0,001; Lockdown 2: 5,71% vs. 6,60%; OR = 0,86; p < 0,001). Nachdem die Effekte auf langfristige und saisonbedingte Trends adjustiert worden waren, konnten die Auswirkungen aber nicht bestätigt werden (Lockdown 1: ber. OR = 0,99; p = 0,73; Lockdown 2: ber. OR = 0,96; p = 0,24). Die Unterschiede während der Lockdownzeiträume waren bei Zwillingsschwangerschaften weniger ausgeprägt (Lockdown 1: 52,99% vs. 56,26%; OR = 0,88; p = 0,15; Lockdown 2: 58,06% vs. 58,91%; OR = 0,97; p = 0,70). Eine geringere Bevölkerungsmobilität hatte keine signifikanten Auswirkungen auf die Frühgeburtenraten bei Einlingsschwangerschaften (p = 0,14), dafür aber auf die Frühgeburtenraten bei Zwillingsschwangerschaften (p = 0,02).

Schlussfolgerungen Es wurden niedrigere Frühgeburtenraten bei Einlings- und Zwillingsschwangerschaften während den beiden Lockdowns im Jahre 2020 beobachtet. Diese Effekte wurden teilweise gemindert, wenn sie auf langfristige und saisonale Trends adjustiert wurden. Die geringere Bevölkerungsmobilität war mit einer niedrigeren Frühgeburtenrate bei Zwillingsschwangerschaften assoziiert.

Key words

COVID-19 - SARS-CoV-2 - preterm birth - lockdown measures - preterm delivery

Schlüsselwörter

COVID-19 - SARS-CoV-2 - Frühgeburt - Lockdown-Maßnahmen

^* Joint senior authors.

Publication History

Received: 04 April 2022

Accepted after revision: 19 May 2022

Article published online:
15 July 2022

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