SARS-CoV-2 infection and COVID-19 vaccination in pregnancy
SARS-CoV-2 infection poses increased risks of poor outcomes during pregnancy, including preterm birth and stillbirth. Viruses that cause pneumonia, including severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), have long been known to be of particular concern during pregnancy. Initially, lockdowns and a tendency towards risk avoidance masked some of the increased risks associated with SARS-CoV-2 infection in pregnancy, but with the passing of time the risks have become clearer.
Obstetric outcomes following SARS-CoV-2 infection
Pregnancy is associated with increased disease severity in those infected with SARS-CoV-2. According to a meta-analysis of 92 studies comparing outcomes for pregnant patients with COVID-19 with age and sex-matched non-pregnant patients, pregnancy increases the risk of the following:
- Intensive care: OR 2.13, 95% confidence interval (CI) 1.54–2.95
- Invasive ventilation: OR 2.59, CI 2.28–2.94
- Extracorporeal membrane oxygenation: OR 2.02, CI 1.22–3.34
A more recent meta-analysis of 111 studies, which compared outcomes for pregnant patients infected with SARS-CoV-2 with those who were not infected, found that infection significantly increased the odds of several critical conditions. Specifically, the data shows increased odds for:
- Premature delivery: OR 1.48, 95% CI 1.22–1.8
- Pre-eclampsia: OR 1.6, CI 1.2–2.1
- Stillbirth: OR 2.36, CI 1.24–4.46
- Neonatal mortality: OR 3.35, CI 1.07–10.5
- Maternal mortality: OR 3.08, CI 1.5–6.3
The increased risk of PTB associated with SARS-CoV-2 infection seems to be driven largely by iatrogenic PTBs, with doctors opting to deliver the infant to try to save the critically ill patient. There is also evidence that both maternal and neonatal outcomes were worse during the Delta wave of the SARS-CoV-2 pandemic than in preceding periods. Furthermore, there is developing concern over the effects of SARS-CoV-2 infection on the placenta, and these effects seem to vary between different viral variants.
Safety and effectiveness of COVID-19 vaccination
Despite these risks, many pregnant individuals have been reluctant to be vaccinated against the virus owing to safety concerns. Although pregnant people were excluded from the first trials of COVID-19 vaccines, the pressing need to protect this group meant that the vaccines were rolled out to them in advance of the completion of clinical trials. We now have extensive real-world data confirming the safety and effectiveness of the vaccines during pregnancy. While we now have extensive data confirming the safety and effectiveness of COVID-19 vaccination during pregnancy, it will also be necessary to determine the effectiveness of these vaccines specifically against newly emerging viral variants, including Omicron.