COVID-19 infection in pregnancy is not associated with stillbirth or early neonatal death, according to a new study.
However, the research, from over 4,000 pregnant women with suspected or confirmed COVID-19, also found women who had a positive test were more likely to have a premature birth.
The study is funded by the COVID-19 rapid research response by UK Research and Innovation (UKRI) and the National Institute for Health Research (NIHR).
The research, published in the journal Ultrasound in Obstetrics and Gynecology, used data from the UK and the USA.
Data from over 4,000 pregnant women
The study team looked at data from 4,004 pregnant women who had suspected or confirmed COVID-19. Of these women:
- 1,606 were from the UK, from a data registry called Pregnancy and Neonatal Outcomes in COVID-19 (PAN-COVID)
- 2,398 were from the US, from the American Academy of Pediatrics Section on Neonatal Perinatal Medicine (SONPM) data registry.
All the women gave birth between January and August 2020.
The research found that no babies died from COVID-19 in the study. There was also no increase in risk of stillbirth or low birth weight.
Higher risk of pre-term birth
However, both the UK and US data suggested a higher risk of pre-term birth (defined as birth before 37 weeks).
In the UK data, 12% of women with suspected or confirmed COVID-19 had a pre-term delivery – 60% higher than the national average rate of 7.5%. In the US data, 15.7% of women had a pre-term birth, 57% higher than the US national average of 10%.
The study team say part of this association may be due to doctors deciding to deliver the baby early due to concerns about the effect of COVID-19 infection on mother and baby. The rate of spontaneous pre-term birth was lower than expected.
Professor Christoph Lees, senior author of the study from Imperial College London, said:
The finding that COVID-19 infection does not increase the risk of stillbirth or baby death is reassuring. However, a suspected or confirmed COVID-19 diagnosis was linked to a higher risk of preterm birth, and it isn’t entirely clear why.
Dr Ed Mullins, co-author from Imperial College London, added:
This study supports the prioritisation of vaccination for women who are pregnant or who plan to become pregnant, and existing measures that protect women in pregnancy from infection, in order to reduce pre-term birth.
Professor Fiona Watt, Executive Chair of Medical Research Council, which helped fund the study, said:
It is obviously critical to understand how COVID-19 affects different groups of people. We’re proud to have funded the present study in which, for the past year, researchers have monitored the health of a substantial number of pregnant women and their babies.
The study’s findings, that there is no increased risk of stillbirth and early neonatal death in women who contracted COVID-19 while pregnant, are reassuring. However, the study highlights the need for more research to determine if, or how, COVID-19 affects maternal outcomes or premature birth.
Women testing positive for virus
The proportion of babies born to mothers with confirmed COVID-19, and who subsequently tested positive for the SARS-CoV-2 virus (which causes COVID-19) was:
- 2% in the UK study
- 8% in the US study.
The majority of women in the study had no pre-existing conditions such as diabetes or a respiratory condition such as asthma.
In the UK study eight of the women died, while four women died in the US study.
The study team say that although these death rates are higher than expected for women giving birth, they are similar to the expected death rates seen among adults with a confirmed COVID-19 infection. This suggests that women in pregnancy are not at a higher risk of death from COVID-19 than non-pregnant women.
Among women in the UK arm of the study:
- 66.5% were European or North American
- 1.9% were Middle Eastern
- 1.1% were North African
- 4.2% were African south of the Sahara or Caribbean
- 7.5% were from the Indian subcontinent
- 9.2% were South East Asian.
Among the US arm of the study:
- 37% were white
- 25% were Black or African
- 4.1% were Asian
- 0.4% were American Indian or Alaska Native American.
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