COVID-19 pandemic and population-level pregnancy and neonatal outcomes: a living systematic review and meta-analysis.

INTRODUCTION

Conflicting reports of increases and decreases in rates of preterm birth (PTB) and stillbirth in the general population during the COVID-19 pandemic have surfaced. The objective of our study was to conduct a living systematic review and meta-analyses of studies reporting pregnancy and neonatal outcomes by comparing the pandemic and pre-pandemic periods.

MATERIAL AND METHODS

We searched PubMed and Embase databases, reference lists of articles published up until 14 May 2021 and included English language studies that compared outcomes between the COVID-19 pandemic time period and pre-pandemic time periods. Risk of bias was assessed using the Newcastle-Ottawa scale. We conducted random-effects meta-analysis using the inverse variance method.

RESULTS

Thirty-seven studies with low-to-moderate risk of bias, reporting on 1 677 858 pregnancies during the pandemic period and 21 028 650 pregnancies during the pre-pandemic period, were included. There was a significant reduction in unadjusted estimates of PTB (28 studies, unadjusted odds ratio [uaOR] 0.94, 95% confidence [CI] 0.91-0.98) but not in adjusted estimates (six studies, adjusted OR [aOR] 0.95, 95% CI 0.80-1.13). The reduction was noted in studies from single centers/health areas (uaOR 0.90, 95% CI 0.86-0.94) but not in regional/national studies (uaOR 0.99, 95% CI 0.95-1.03). There was reduction in spontaneous PTB (five studies, uaOR 0.89, 95% CI 0.82-0.98) and induced PTB (four studies, uaOR 0.90, 95% CI 0.81-1.00). There was no reduction in PTB when stratified by gestational age <34, <32 or <28 weeks. There was no difference in stillbirths between the pandemic and pre-pandemic time periods (21 studies, uaOR 1.08, 95% CI 0.94-1.23; four studies, aOR 1.06, 95% CI 0.81-1.38). There was an increase in birthweight (six studies, mean difference 17 g, 95% CI 7-28 g) during the pandemic period. There was an increase in maternal mortality (four studies, uaOR 1.15, 95% CI 1.05-1.26), which was mostly influenced by one study from Mexico. There was significant publication bias for the outcome of PTB.

CONCLUSIONS

The COVID-19 pandemic time period may be associated with a reduction in PTB; however, referral bias cannot be excluded. There was no difference in stillbirth between the pandemic and pre-pandemic period.