Evidence Matters

Are COVID-19 Mitigation Measures Associated with a Reduction in Preterm Births?

BACKGROUND AND PURPOSE:

Been et al. (The Lancet, 2020) examined the impact of the COVID-19 mitigation measures on the incidence of preterm birth

Assessed response to mitigations implemented in Netherlands in a stepwise fashion (March 9, March 15, and March 23, 2020)
March 9
- Using paper handkerchiefs | Sneezing or coughing in one’s elbow | Regular handwashing | Advice against handshaking
- Stay at home when experiencing cold symptoms or fever or in contact with COVID-19-positive person or having visited a high-risk area
March 12
- Events of more than 100 individuals cancelled | Work from home when possible | Stay home if symptomatic (fever, respiratory complaints) | Advice against social interaction and visiting older people
March 15
- School closures and childcare facilities | Closures of hospitality industry and of non-essential services involving physical contact | Physical distancing introduced (1.5 meter rule)
March 23
- All events and gatherings cancelled | No groups of >3 people allowed in public areas (except households and children) | Fines for not complying with physical distancing | Municipalities can close busy places and shops
Data sources
- Neonatal dried blood spot screening program (2010 to 2020)
- National perinatal registry data
Study design
- Stratified analyses based on gestational age subgroups
- Researchers assessed potential modifiers
  - Neighborhood socioeconomic status
  - Sex
  - Small-for-gestational-age status

1,599,547 neonatal records analyzed
- 56,720 births occurring after implementation of COVID-19 mitigation measures (March 9)
There were consistent reductions in the incidence of preterm birth across various time windows surrounding March 9
- ± 2 months: Odds ratio (OR) 0.77 (95% CI, 0.66 to 0.91); p = 0.0026; n=531,823
- ± 3 months: OR 0.85 (95% CI, 0.73 to 0.98); p = 0.028; n = 796,531
- ± 4 months: OR 0.84 (95% CI, 0.73 to 0.97); p = 0.023; n = 1,066,872
Incidence of preterm birth experienced a decrease of smaller magnitude following the March 15 measures, but these were 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
- Confined to neighborhoods of high socioeconomic status, but effect modification was not statistically significant

Implementation of initial measures to stop the spread of COVID-19 on March 9 in the Netherlands was associated with a reduction in preterm births in the following months
The authors hypothesize the following factors that may account for this reduction
- Hygiene measures and behavioral changes on the part of pregnant women
- Less physically demanding work and less shift work and work-related stress due to business closures
- Reduction in air pollution
- Changes in obstetric practice or care-seeking behavior

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