COVID-19 must catalyse key global natural experiments

Impact of COVID-19 mitigation measures on perinatal outcomes in the Netherlands

OBJECTIVE

Investigate the acute impact of COVID-19 mitigation measures implemented in March 2020 on a comprehensive range of perinatal outcomes.

STUDY DESIGN

National registry-based quasi-experimental study.

METHODS

We obtained data from the Dutch Perinatal Registry (2010-2020) which was linked to multiple population registries containing sociodemographic variables. A difference-in-discontinuity approach was used to examine the impact of COVID-19 mitigation measures on various perinatal outcomes. We investigated preterm birth incidence across onset types, alongside other perinatal outcomes including low birth weight, small-for-gestational-age, NICU admission, low-APGAR-score, perinatal mortality, neonatal death, and stillbirths.

RESULTS

The analysis of the national-level dataset revealed a consistent pattern of reduced preterm births after the enactment of COVID-19 mitigation measures on March 9, 2020 (OR = 0.80, 95% CI 0.68-0.96). A drop in spontaneous preterm births post-implementation was observed (OR = 0.80, 95% CI 0.62-0.98), whereas no change was observed for iatrogenic births. Regarding stillbirths (OR = 0.95, 95% CI 0.46-1.95) our analysis did not find compelling evidence of substantial changes. For the remaining outcomes, no discernible shifts were observed.

CONCLUSIONS

Our findings confirm the reduction in preterm births following COVID-19 mitigation measures in the Netherlands. No discernible changes were observed for other outcomes, including stillbirths. Our results challenge previous concerns of a potential increase in stillbirths contributing to the drop in preterm births, suggesting alternative mechanisms.

Preterm birth and stillbirth rates associated with socioeconomic disparities during COVID-19 pandemic: a population-based cross-sectional study

BACKGROUND

Conflicting evidence exists on the impact of the COVID-19 pandemic restrictions on preterm birth (PTB) and stillbirth rates. We aimed to evaluate changes in PTB and stillbirth rates before and during the pandemic period and assess the potential effect modification of socioeconomic status (SES).

METHODS

Using the linked administrative health databases from Manitoba, Canada, we conducted a cross-sectional study among all pregnant women, comparing 3.5 years pre-pandemic (1 October 2016 to 29 February 2020) to the first year of the pandemic (1 March 2020 to 31 March 2021). We used generalised linear models to assess the quarterly rates of PTB (<37 weeks) and stillbirths. We calculated the predicted trends based on pre-pandemic period data. Finally, we evaluated the PTB and stillbirth rates among lower and higher SES pregnant women (average annual household income) using subgroup analysis and interaction models.

RESULTS

We examined 70 931 pregnancies in Manitoba during the study period. The risk of PTB increased by 7.7% (95%CI 1.01 to 1.13) and stillbirths by 33% (95% CI 1.08 to 1.64) during the pandemic period. Following COVID-19 restrictions implemented in March 2020, there were increases in the quarterly rates of both PTB (immediate increase (β2)=1.37; p=0.0247) and stillbirths (immediate increase (β2)=0.12; p=0.4434). Among the lower income groups, the pandemic restrictions resulted in an immediate relative increase in PTB and stillbirth rates by 20.12% (immediate increase (β2)=3.17; p=0.0057) and 27.19% (immediate increase (β2)=0.48; p=0.0852). However, over the pandemic, the overall PTB rate significantly decreased as a rebound effect by 0.85% per quarter (p=0.0004), whereas the overall stillbirth rate did not decrease significantly (slope decrease (β3) =-0.01; p=0.8296) compared with the pre-pandemic period. The quarterly rates during the pandemic among the higher income group decreased by 0.39% (p=0.1296) for PTB and increased by 0.07% (p=0.1565) for stillbirth. We observed an effect modification by SES for PTB rates (p=0.047).

CONCLUSION

While the onset of COVID-19 pandemic restrictions was not associated with significant effects on stillbirth rates, we observed an immediate and rebound effect on PTB rates. The impact of COVID-19 on preterm birth was dependent on SES, with higher influence on families with lower SES. Further studies are needed to detect future trend changes during pandemic waves after 2021 and assess potential underlying mechanisms.

Changes in fetal growth restriction and retinopathy of prematurity during the coronavirus disease 2019 pandemic: A cross-sectional study

Purpose

To investigate changes in the number of preterm infants, low birth weight infants, and infants with fetal growth restriction (FGR) or retinopathy of prematurity (ROP) during the coronavirus disease 2019 (COVID-19) pandemic.

Methods

In this retrospective cross-sectional study, we reviewed the medical records of infants born and admitted to the neonatal intensive care unit and growth care unit of Shiga University of Medical Science Hospital before the COVID-19 pandemic (April 1, 2019 to September 30, 2019) and during the pandemic (April 1, 2020 to September 30, 2020). Medical records of infants’ mothers were also collected. Preterm infants, low birth weight infants, infants with FGR, infant and maternal factors associated with FGR, and infants requiring treatment for ROP were compared between the two periods.

Results

There were fewer infants born at < 28 weeks of gestation, infants with birth weight < 1,500 g, and infants with FGR during the pandemic period than the pre-pandemic period (pre-pandemic: n = 4 vs. during pandemic: n = 0, P = 0.048; pre-pandemic: n = 15 vs. during pandemic: n = 6, P = 0.02; and pre-pandemic: n = 31 vs. during pandemic: n = 12, P = 0.0002, respectively). There were no significant differences in any infant or maternal factors associated with FGR. The number of infants requiring treatment for ROP decreased during the pandemic, although this difference was not statistically significant (pre-pandemic: n = 3 vs. during pandemic: n = 0, P = 0.08).

Conclusions

Our findings showed a reduction in the number of infants with FGR during the COVID-19 pandemic. The number of infants born at < 28 weeks of gestation and infants with birth weight < 1,500 g also decreased during the pandemic period. There was a trend toward fewer infants requiring treatment for ROP during the COVID-19 pandemic.

Adverse pregnancy outcomes during the COVID-19 lockdown. A descriptive study

BACKGROUND

The ongoing spread coronavirus disease worldwide has caused major disruptions and led to lockdowns. Everyday lifestyle changes and antenatal care inaccessibility during the coronavirus disease 2019 (COVID-19) pandemic have variable results that affect pregnancy outcomes. This study aimed to assess the alterations in stillbirth, neonatal-perinatal mortality, preterm birth, and birth weight during the COVID-19 national lockdown.

METHODS

We used the data from the Jordan stillbirths and neonatal death surveillance system to compare pregnancy outcomes (gestational age, birth weight, small for gestational age, stillbirth, neonatal death, and perinatal death) between two studied periods (11 months before the pandemic (May 2019 to March 2020) vs. 9 months during the pandemic (April 2020 to March 1st 2020). Separate multinomial logistic and binary logistic regression models were used to compare the studied outcomes between the two studied periods after adjusting for the effects of mother's age, income, education, occupation, nationality, health sector, and multiplicity.

RESULTS

There were 31106 registered babies during the study period; among them, 15311 (49.2%) and 15795 (50.8%) births occurred before and during the COVID-19 lockdown, respectively. We found no significant differences in preterm birth and stillbirth rates, neonatal mortality, or perinatal mortality before and during the COVID-19 lockdown. Our findings report a significantly lower incidence of extreme low birth weight (ELBW) infants (<1kg) during the COVID-19 lockdown period than that before the lockdown (adjusted OR 0.39, 95% CI 0.3-0.5: P value <0.001) CONCLUSIONS: During the COVID-19 lockdown period, the number of infants born with extreme low birth weight (ELBW) decreased significantly. More research is needed to determine the impact of cumulative socio-environmental and maternal behavioral changes that occurred during the pandemic on the factors that contribute to ELBW infants.

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

Background

Preterm birth is the leading cause of child mortality globally, with many survivors experiencing long-term adverse consequences. Preliminary evidence suggests that numbers of preterm births greatly reduced following implementation of policy measures aimed at mitigating the effects of the COVID-19 pandemic. We aimed to study the impact of the COVID-19 mitigation measures implemented in the Netherlands in a stepwise fashion on March 9, March 15, and March 23, 2020, on the incidence of preterm birth.

Methods

We used a national quasi-experimental difference-in-regression-discontinuity approach. We used data from the neonatal dried blood spot screening programme (2010–20) cross-validated against national perinatal registry data. Stratified analyses were done according to gestational age subgroups, and sensitivity analyses were done to assess robustness of the findings. We explored potential effect modification by neighbourhood socioeconomic status, sex, and small-for-gestational-age status.

Findings

Data on 1 599 547 singleton neonates were available, including 56 720 births that occurred after implementation of COVID-19 mitigation measures on March 9, 2020. Consistent reductions in the incidence of preterm birth were seen across various time windows surrounding March 9 (± 2 months [n=531 823] odds ratio [OR] 0·77, 95% CI 0·66–0·91, p=0·0026; ± 3 months [n=796 531] OR 0·85, 0·73–0·98, p=0·028; ± 4 months [n=1 066 872] OR 0·84, 0·73–0·97, p=0·023). Decreases in incidence observed following the March 15 measures were of smaller magnitude, but not statistically significant. No changes were observed after March 23. Reductions in the incidence of preterm births after March 9 were consistent across gestational age strata and robust in sensitivity analyses. They appeared confined to neighbourhoods of high socioeconomic status, but effect modification was not statistically significant.

Interpretation

In this national quasi-experimental study, initial implementation of COVID-19 mitigation measures was associated with a substantial reduction in the incidence of preterm births in the following months, in agreement with preliminary observations elsewhere. Integration of comparable data from across the globe is needed to further substantiate these findings and start exploring underlying mechanisms.

Funding

None.