How deadly is Covid-19 for pregnant women? Risk of severe illness and death highest in 35-44 age group, says CDC
Pregnant women who are infected with the coronavirus are at a greater risk of severe illness and death compared to women who are not pregnant, according to researchers from the US Centers for Disease Control and Prevention (CDC). While the overall risk remains low, they found that intensive care unit (ICU) admission, invasive ventilation, need for life support, and death were more likely in pregnant women than in nonpregnant women.
While the increased risks for severe disease related to pregnancy “were apparent” in nearly all age groups studied, the analysis shows that pregnant women aged 35-44 years with Covid-19 were nearly four times as likely to require invasive ventilation and twice as likely to die than were nonpregnant women of the same age.
“Although the absolute risks for severe outcomes for women were low, pregnant women were at increased risk for severe Covid-19-associated illness. Pregnant women should be counseled about the risk for severe Covid-19-associated illness including death, measures to prevent infection with SARS-CoV-2 (the virus that causes coronavirus) should be emphasized for pregnant women and their families. These findings can inform clinical practice, risk communication, and medical countermeasure allocation,” write authors.
The experts say the finding might be related to physiologic changes in pregnancy. “This included increased heart rate and oxygen consumption, decreased lung capacity, a shift away from cell-mediated immunity, and increased risk for thromboembolic disease (when blood clots form in blood vessels),” they add.
The findings
During January 22-October 3, 5,003,041 laboratory-confirmed Covid-19 cases were reported to the agency, including 1,300,938 (26%) cases in women aged 15-44 years. Data on pregnancy status were available for 461,825 (35.5%) women, 30,415 (6.6%) of whom were pregnant and 431,410 (93.4%) of whom were nonpregnant. Among all women with known pregnancy status, 409,462 (88.7%) were symptomatic, including 23,434 pregnant women, accounting for 5.7% of all symptomatic women with coronavirus, and 386,028 nonpregnant women.
Compared with nonpregnant women, pregnant women more frequently were admitted to an ICU (10.5 versus 3.9 per 1,000 cases, adjusted risk ratio or ARR 3.0), received invasive ventilation (2.9 versus 1.1 per 1,000 cases, ARR 2.9), and received extracorporeal membrane oxygenation or ECMO (0.7 versus 0.3 per 1,000 cases, ARR 2.4). In ECMO, blood is pumped outside of the body to a heart-lung machine that removes carbon dioxide and sends oxygen-filled blood back to tissues in the body.
Thirty-four deaths (1.5 per 1,000 cases) were reported among 23,434 symptomatic pregnant women, and 447 (1.2 per 1,000 cases) were reported among 386,028 nonpregnant women, reflecting a 70% increased risk (ARR 1.7) for death associated with pregnancy.
The risk of receiving invasive ventilation among pregnant women aged 15-24 years was 3 times that of nonpregnant women. Among pregnant women aged 35-44 years, it was 3.6 times that of nonpregnant women. “Irrespective of pregnancy status, ICU admissions, receipt of invasive ventilation, and death occurred more often among women aged 35-44 years than among those aged 15-24 years,” the findings state.
Regardless of pregnancy status, non-Hispanic Black women experienced a disproportionate number of deaths relative to their distribution among reported cases. While non-Hispanic Black women made up 14.1% of women included in this analysis, they represented 176 (36.6%) deaths overall, including nine of 34 (26.5%) deaths among pregnant women and 167 of 447 (37.4%) deaths among nonpregnant women.
Pregnant Asian and Native Hawaiian/Pacific Islander women also appeared to be a disproportionately greater risk for ICU admission. Hispanic pregnant women of any race not only experienced a disproportionate risk for Covid-19 infection but also a higher risk for death compared with nonpregnant Hispanic women. “Increased risk for ICU admission among pregnant women was observed for all strata but was particularly notable among non-Hispanic Asian women and non-Hispanic Native Hawaiian/Pacific Islander women. In addition, among Hispanic women, pregnancy was associated with 2.4 times the risk for death,” says the team.
Risk of preterm delivery
A separate CDC study suggests that pregnant women could be at risk for preterm birth. Among 3,912 infants born to women with Covid-19 infection, 12.9% were preterm (that is, born before 37 weeks), higher than a national estimate of 10.2%. Among 610 (21.3%) infants with testing results, 2.6% had positive coronavirus results, primarily those born to women with infection at delivery.
Of the 4,527 fetuses and newborns, 4,495 (99.3%) were live births, including 79 sets of twins and one set of triplets. Further, 32 were miscarriages with 12 of them (0.3%) at less than 20 weeks’ gestation (time between conception and birth) and 20 (0.4%) at 20 weeks’ or longer gestation. Among 3,486 live births with weight, gestational age, and sex recorded (77.6%), 198 (5.7%) were small for gestational age. Nine of 4,495 infants (0.2%) died in the hospital.
“Because the majority of pregnant women with Covid-19 reported thus far experienced infection in the third trimester, ongoing surveillance is needed to assess the effects of infections in early pregnancy, as well the longer-term outcomes of exposed infants. These findings can inform neonatal testing recommendations, clinical practice, and public health action and can be used by healthcare providers to counsel pregnant women on the risks of coronavirus infection, including preterm births,” recommend authors. They add, “Pregnant women and their household members should follow recommended infection prevention measures, including wearing a mask, social distancing, and frequent handwashing when going out or interacting with others or if there is a person within the household who has had coronavirus exposure.”