Last week, the Centers for Disease Control and Prevention (CDC) published two new studies that have shown pregnant women who are infected with the highly transmissible Delta strain are at increased risk of having a stillbirth or dying during childbirth, according to NBC News.

The findings expand on reports from doctors who have noticed a rise in pregnant women becoming severely ill with COVID-19, particularly since the Delta variant has taken hold.

Dr. Ellie Ragsdale, Director of Fetal Intervention at UH Cleveland Medical Center, said, “We are seeing loads of pregnancy complications from COVID-19 infection.”

Those pregnancy complications include premature deliveries, abnormally high blood pressure in pregnant women, as well as pregnancy loss, according to Dr. Ragsdale, who was not part of the CDC studies.

In one study, researchers analyzed the outcomes of over 1.2 million pregnancies from March 2020 to September 2021.

Generally, the rate of stillbirths was very low (0.59%) in the United States before the pandemic. And that rate remained similar even when the pandemic began, among women who were never infected with COVID-19. However, the rate of stillbirths increased to nearly 1% among pregnant women infected with the virus, according to the CDC report.

And since Delta become a dominant strain in July 2021, the rate of stillbirth increased exponentially by 2.7%.

The authors of the study wrote, “Although stillbirth was a rare outcome overall,” documented COVID diagnosis was associated with a marked increase in the risk for stillbirth, “with a stronger association during the period of delta variant predominance.”

The study does not prove Delta causes more fetal deaths, but OB/GYNs are noticing differences in how much oxygen fetuses can absorb, depending on whether their mothers have been diagnosed with COVID, according to NBC News.

Dr. Ragsdale said she and her colleagues have noted that pregnant women with COVID-19 infection have a difficult time getting oxygen-rich blood to their growing fetuses.

She said, “We’re seeing areas of the placenta that are oxygen-deprived. That’s the baby’s source of oxygen and survival in pregnancy.”

Experts said the CDC report did not analyze vaccination status, but unvaccinated pregnant women may be at particular risk.

In addition, the coronavirus can also be deadly to expecting mothers with underlying health conditions.

A separate CDC report looked at 15 deaths among COVID-positive pregnant women in Mississippi, who had some kind of chronic health condition, such as diabetes or high blood pressure. None of them had been fully vaccinated.

In September, the CDC issued guidance urging pregnant women to get vaccinated against Covid.

Dr. Zsakeba Henderson, Deputy Chief Medical and Health Officer for the March of Dimes, said, “We have evidence to show there is no increased risk of miscarriage or poor pregnancy outcomes from the vaccine. All evidence points to the safety of this vaccine.”

March of Dimes is a nonprofit organization that works to improve the health of mothers and babies.