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

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.

Keywords: COVID-19; Epidemics; Infant, extremely premature; Infant, premature; Perinatal death; Stillbirth.

Fig. 1

The timeline of COVID-19 events in Denmark leading up to the lockdown. Different categories of events (orienting the public = orientation, published guidelines = guidelines, local cases and local transmission = cases/transmission, policy response = policy response, the WHO declaration of a pandemic = WHO, the declaration of the lockdown = lockdown declaration) are indicated by different colours. Data summarized from [31, 54, 55]

Fig. 2

Mean number of live births and stillbirths per month, from January to September. 2015–2019 (blue; error bars represent 1SD) and 2020 (red). A Live births (all gestational ages), B stillbirths (all gestational ages), C live births (extremely preterm, gestational age 22–28 weeks), and D stillbirths (gestational age 22–28 weeks). Statistically significant differences are indicated by asterisks. *represents p ≤ 0.05, and ** represents p < 0.01

Fig. 3

The effect of COVID-19 restrictions on combined extremely preterm stillbirth and live birth rates. Combined rates for 2020 (red columns) are compared to the aggregate rates from the same months in 2015–2019 (blue columns; error bars represent 1SD). The sum of the rates is significantly decreased in February and March 2020. Furthermore, the combined rate is decreased in all months except May and June 2020