Reduction in preterm births during the COVID-19 lockdown in Ireland: a natural experiment allowing analysis of data from the prior two decades

Abstract

Background: Aetiology of preterm birth (PTB) is heterogeneous and preventive strategies remain elusive. Socio-environmental measures implemented as Ireland s prudent response to the SARS-CoV-2 virus (COVID-19) pandemic represented, in effect, a national lockdown and have possibly influenced the health and wellbeing of pregnant women and unborn infants. Cumulative impact of such socio-environmental factors operating contemporaneously on PTB has never been assessed before. Methods: Regional PTB trends of very low birth weight (VLBW) infants in one designated health area of Ireland over two decades were analysed. Poisson regression and rate ratio analyses with 95% CI were conducted. Observed regional data from January to April 2020 were compared to historical regional and national data and forecasted national figures for 2020. Results: Poisson regression analysis found that the regional historical VLBW rate per 1000 live births for January to April, 2001 to 2019 was 8.18 (95% CI: 7.21, 9.29). During January to April 2020, an unusually low VLBW rate of just 2.17 per 1000 live births was observed. The rate ratio of 3.77 (95% CI: 1.21, 11.75), p = 0.022, estimates that for the last two decades there was, on average, 3.77 times the rate of VLBW, compared to the period January to April 2020 during which there is a 73% reduction. National Irish VLBW rate for 2020 is forecasted to be reduced to 400 per 60,000 births compared to historical 500 to 600 range. Conclusion: An unprecedented reduction in PTB of VLBW infants was observed in one health region of Ireland during the COVID-19 lockdown. Potential determinants of this unique temporal trend reside in the summative socio-environmental impact of the COVID-19 dictated lockdown. Our findings, if mirrored in other regions that have adopted similar measures to combat the pandemic, demonstrate the potential to evaluate these implicated interdependent behavioural and socio-environmental modifiers to positively influence PTB rates globally.

Impact of COVID-19 mitigation measures on the incidence of preterm birth: a national quasi-experimental study

“…Again, this is a large relative reduction but a small reduction in absolute terms. The observed reduction in preterm births in Denmark and Ireland predominantly affected the smallest babies, 2 , 3 whereas the decrease was fairly constant across gestational age strata in our study. The vast majority of preterm babies are born moderately to late preterm (ie, 32 weeks and 0 days to 36 weeks and 6 days), and our data suggest that prevention might be possible for all levels of prematurity.…”

“…Extension of the COVID-19 measures introduced 1 week and 2 weeks later had no significant effect on preterm births. Taken together with preliminary evidence from other countries, 2 , 3 these findings provide opportunities to identify novel preventive strategies for preterm birth.…”

“…In these studies, data on post-implementation births were available for 5162 2 and 1381 births. 3 The Netherlands has around 170 000 births annually, which translates into around 60 000 births after implementation of mitigation measures, including around 4000 preterm births. Given the positive findings in earlier studies, 2 , 3 which had much smaller sample sizes, we anticipated that our dataset would provide ample statistical power to identify an association of similar magnitude between the COVID-19 mitigation measures and preterm births in the Netherlands.…”

“…The sudden occurrence of the pandemic and the scale and immediacy of the policy responses taken provide a unique opportunity to evaluate their effects as a natural experiment. 1 Reports from Denmark 2 and Ireland 3 independently provided evidence indicating substantial reductions in the number of extremely preterm and very-low-birthweight births following national COVID-19 mitigation measures. Several potential underlying mechanisms have been proposed, including improvements in ambient air quality and reductions in maternal stress and incidence of infections.…”

“…Several potential underlying mechanisms have been proposed, including improvements in ambient air quality and reductions in maternal stress and incidence of infections. 3 …”