The risk of stillbirth is almost twice as high for pregnant women with Covid-19 than for those without the disease, according to a large study conducted by the US health authorities on Friday.
The US Centers for Disease Control and Prevention (CDC) analyzed data from more than 1.2 million births between March 2020 and September 2021, from a hospital database. The American public health organization considers stillbirth the fetal death that occurs after the 20th week of pregnancy.
In most cases, 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.
Specifically, during the study period, 1.26% of births were stillbirths to pregnant women infected with Covid-19, compared with 0.64% for the rest.
The Delta variant of the new coronavirus also increased that risk, according to the CDC, which analyzed the time periods before and after the variant became dominant in the United States in July 2021.
Compared with uninfected women, the risk increased by 1.47 for mothers who were positive for Covid-19 in the pre-Delta period and by 4.04 when the variant prevailed.
“More studies are needed to examine the role of pregnancy complications by Covid-19 in the risk of stillbirth,” the CDC said.
Some studies in the past have suggested inflammation and reduced blood flow to the placenta as causes.
The CDC study is the most important to date and proves the correlation between stillbirth and Covid-19, they said.
The authors of the study stressed that it could not be determined whether the women with Covid-19 were ill at the time of their hospitalization or had been infected in the past. The vaccination regime for women was also not available.
U.S. health authorities strongly recommend that pregnant women be vaccinated against Covid-19 before or during pregnancy.
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