The risk of a stillborn child is about twice as high for pregnant women with Covid-19 as for those who have not contracted the disease, according to a large study by American health authorities published on Friday. The Centers for Disease Control and Prevention (CDC) analyzed more than 1.2 million childbirths between March 2020 and September 2021, from a database of hospitals. The public health agency considers a stillborn child from the 20th week.
In general, stillbirths were rare (0.65% of births, or about 8,150). But the risk of stillbirth was 1.90 times higher in women with Covid-19. Concretely, over this period, 1.26% of births were a stillborn child for women who contracted Covid-19, compared to 0.64% for the others.
An increased risk by the Delta variant
The Delta variant also increased this risk, noted the CDC, which analyzed the periods before and after this variant became dominant in the country, in July 2021. Compared to uninfected women, the risk was thus increased by 1.47 for mothers positive for Covid-19 during the pre-Delta period, and 4.04 once the majority variant. “Further studies are needed to examine the role of maternal complications related to Covid-19 on the risk of stillbirth,” the CDC wrote.
Some studies in the past have suggested that the cause may include inflammation and decreased blood flow to the placenta. The CDC study is the largest that has demonstrated the link between stillbirths and Covid-19 to date, they said. They said she could not determine if the women with Covid-19 were sick when they were hospitalized, or if they had been infected beforehand. The vaccination status of the women was also not available. The American health authorities strongly recommend that pregnant women get vaccinated against Covid-19, before or during their pregnancy.