COVID-19 in Pregnancy: Higher Risk of Severe Illness, 2020

This page summarizes a CDC report published in November 2020, covering cases from January to October 2020. Its prevention advice reflects the guidance of that time, before COVID-19 vaccines were available.

Early reports suggested that pregnant women with COVID-19 might be at higher risk of severe illness than other women. This larger CDC analysis, of about 400,000 symptomatic women aged 15 to 44, confirmed it.

The data

From January 22 to October 3, 2020, 5,003,041 laboratory-confirmed SARS-CoV-2 infections were reported to CDC through national case surveillance, 1,300,938 (26.0%) of them in women aged 15–44. Pregnancy status was known for 461,825 of these women (35.5%): 30,415 (6.6%) were pregnant and 431,410 were not. The analysis was limited to the 409,462 women with symptoms, to avoid counting pregnant women found only through routine testing when they came to deliver. Of those, 23,434 (5.7%) were pregnant, close to the roughly 5% of women of this age who are pregnant at any given time.

Pregnant women with COVID-19 were more often Hispanic (29.7%) and less often non-Hispanic White (23.5%) than nonpregnant women (22.6% Hispanic, 31.7% White). Cough, headache, muscle aches and fever were the most common symptoms, and most symptoms were reported less often by pregnant women.

Severe outcomes

After adjusting for age, race and ethnicity, diabetes, cardiovascular disease (including high blood pressure) and chronic lung disease, pregnant women were significantly more likely to have every severe outcome studied:

There were 34 deaths among the 23,434 symptomatic pregnant women and 447 among the 386,028 who were not pregnant, a 70% higher risk of death with pregnancy. The absolute risks were low, but the added risk was clear.

Who was most affected

• Age. Whether pregnant or not, women aged 35–44 were more likely than those aged 15–24 to need intensive care or a ventilator or to die. Pregnant women aged 35–44 were 3.6 times as likely to need invasive ventilation as nonpregnant women of the same age, and twice as likely to die; among 15- to 24-year-olds the ventilation risk was 3.0 times higher.
• Race and ethnicity. The added risk of intensive care with pregnancy was especially high among Asian women (6.6 times) and Native Hawaiian or Pacific Islander women (3.7 times). Among Hispanic women, pregnancy was linked to 2.4 times the risk of death. Black women made up 14.1% of the women studied but 36.6% of all deaths (176): 9 of the 34 deaths among pregnant women and 167 of the 447 among nonpregnant women.

Hispanic women made up 30% and White women 24% of symptomatic pregnant women with COVID-19 whose race was known, compared with 24% and 51% of all women who gave birth in 2019, which suggests Hispanic pregnant women were infected disproportionately.

Why pregnancy may raise the risk

The authors point to physical changes of pregnancy: a faster heart rate and higher oxygen use, reduced lung capacity, a shift away from cell-mediated immunity and a higher risk of blood clots. Earlier data had shown more intensive care and ventilation among pregnant women; this analysis, with nearly five times as many symptomatic women, added a higher risk of ECMO and death. A meta-analysis had found no added risk of intensive care or death for pregnant women with seasonal flu, but earlier flu pandemics, including 2009 H1N1, did put pregnant women at higher risk of severe illness and death.

Limitations: case reporting is voluntary and varies between jurisdictions; pregnancy status was missing for 64.5% of cases, race and ethnicity for about a quarter of those with known status, and symptoms and underlying conditions for about half; and severe cases are more likely to be reported, so all cases were used as the denominator as a conservative estimate. Outcome data were updated through October 28, 2020, to allow time for severe outcomes to be recorded.

Advice at the time

The authors urged that pregnant women be told about their risk of severe COVID-19 and its warning signs, and encouraged to seek care promptly if they had symptoms. To lower their risk of infection, pregnant women were advised to limit unnecessary contact with people who might have been exposed, including within their household; to wear a mask, keep their distance and avoid unmasked people when out; to wash hands often; and to keep up with flu vaccination and prenatal care. Providers were pointed to guidelines on managing COVID-19 in pregnancy, and CDC adapted its Surveillance for Emerging Threats to Mothers and Babies Network (SET-NET) to follow pregnancy and newborn outcomes.

Sources

• Zambrano LD, Ellington S, Strid P, et al. "Update: Characteristics of Symptomatic Women of Reproductive Age with Laboratory-Confirmed SARS-CoV-2 Infection by Pregnancy Status — United States, January 22–October 3, 2020." MMWR 69(44). https://www.cdc.gov/mmwr/volumes/69/wr/mm6944e3.htm (as corrected)
• NIH COVID-19 treatment guidelines: https://www.covid19treatmentguidelines.nih.gov/