Stillbirth Risk Spiked With Delta

For pregnant women with COVID-19 during the Delta period, the risk for stillbirth was four times higher if they had their diagnosis at delivery while mortality was increased fivefold in a small study from Mississippi, according to two CDC reports.

From March 2020 to September 2021, the risk for stillbirth was 90% higher among women who had a COVID-19 diagnosis at delivery versus those who did not, with a huge difference between the pre-Delta (adjusted relative risk [aRR] 1.47, 95% CI 1.27-1.71) and Delta period starting in July 2021 (aRR 4.04, 95% CI 3.28-4.97), reported Carla L. DeSisto, PhD, of the CDC, and colleagues, writing in the Morbidity and Mortality Weekly Report (MMWR).

A second MMWR report by Laurin Kasehagen, PhD, of the CDC, and colleagues, showed that the COVID-19 mortality rate among pregnant women in Mississippi increased from 5 per 1,000 infections (95% CI 1.7-10.3) in the pre-Delta period to 25 per 1,000 infections (95% CI 11.3-46.8) during Delta.

Stillbirth Risk

For their study, DeSisto's group analyzed the Premier Healthcare Database Special COVID-19 Release, identifying 1.24 million deliveries at 736 hospitals from March 2020 to September 2021.

Overall, there were 8,154 stillbirths, with 273 occurring among 21,653 deliveries involving patients with a COVID-19 diagnosis at delivery (1.26%) and 7,881 among the 1.22 million deliveries without such a diagnosis (0.64%).

The researchers were unable to assess vaccination status in the analysis. However, they noted that because only 30% of pregnant people were vaccinated by July, it is likely that the vast majority were unvaccinated.

"Although stillbirth was a rare outcome overall, a COVID-19 diagnosis documented during the delivery hospitalization was associated with an increased risk for stillbirth," wrote DeSisto and colleagues, "with a stronger association during the period of Delta variant predominance."

Kjersti Aagaard, MD, PhD, a professor of ob/gyn at Baylor College of Medicine in Houston, who was not involved in the study, told MedPage Today by email that the effects of Delta still need to be further examined due to the strain on healthcare systems during this time period, citing how lack of available hospital beds or other care limitations could have played a role in the findings as well.

Still, she said, vaccination against COVID-19 in the pregnant population is the best prevention strategy, and has the potential to reduce not only maternal disease severity and death, but also stillbirth.

"It is rare that we can offer solutions for the prevention of stillbirth," Aagaard said. "In this case, we can."

In the study, a higher risk for stillbirth among deliveries with COVID-19 was also seen when certain comorbidities or other factors played a part, including chronic hypertension, a multiple gestation pregnancy, an adverse cardiac event, placental abruption, sepsis, shock, acute respiratory distress syndrome, mechanical ventilation, and ICU admission. The associations for adverse cardiac events and ICU admission were stronger during the Delta period.

Approximately 15% of the pregnant patients had obesity, 11% had diabetes, 17% had a hypertensive disorder, 2% had multiple gestation pregnancies, and 5% smoked tobacco.

The authors noted several limitations, including the reliance on administrative data, whether the documented COVID-19 diagnosis was a past or current infection, and the possibility that mothers with more severe cases were tested due to a lack of universal COVID-19 screening.

Increased Mortality in Pregnancy

Kasehagen's group analyzed COVID-19 case and death data from the Mississippi State Department of Health from March 2020 to October 2021, finding 15 COVID-19-associated deaths among 1,637 pregnant people infected with SARS-CoV-2, for a mortality rate of 9 per 1,000 infections.

Of the 15 pregnant women who died, six died in the pre-Delta period (March 2020 to June 2021) and nine died in the Delta period (July to October 2021). Median age of the decedents was 30 years old. Median time from symptom onset to death was 18 days, both before and after Delta's arrival. All but one of the pregnant patients had underlying medical conditions. Nine of the 15 women were non-Hispanic Black, three were white, and three were Hispanic.

"CDC recommends COVID-19 vaccination for pregnant women to prevent serious illness, death, and adverse pregnancy outcomes from COVID-19," Kasehagen's group wrote. "Given existing disparities in vaccination rates among pregnant women, partnerships to address vaccine access, hesitancy, or other concerns about vaccination can enhance fair and just access to COVID-19 vaccination, including among Black persons and Hispanic persons."

All patients who died were admitted to the ICU, and all but one were put on mechanical ventilation. Seven of the patients had an emergency C-section, and three died during their pregnancy. One of the patients who died during pregnancy had a spontaneous abortion at 9 weeks' gestation, and two had stillbirths at 22 and 23 weeks of pregnancy. Twelve of the pregnant women died after birth, with the deaths occurring at a median 5 days' postpartum.

None of the patients received monoclonal antibodies and none were fully vaccinated (one was partially vaccinated). Five of the deaths occurred before COVID-19 vaccines became available in December 2020.

Limitations of the study included the difficulty of identifying pregnancy-related mortality via death certificates and potential underestimates in COVID-19 reporting systems. Also, because of the small number of deaths, the researchers did not determine statistical significance of the mortality rate differences between the pre-Delta and Delta time periods.

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