Severe/critical COVID-19 may up perinatal risk

Critical or severe COVID-19 disease could raise the risk of negative perinatal outcomes in pregnant women, according to an observational study from the US.

“Compared with asymptomatic patients, those with severe/critical COVID-19, but not those with mild/moderate COVID-19, were at increased risk of perinatal complications,” said study author Dr Torri Metz from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units (MFMU) Network, Bethesda, Maryland, US, who presented the findings at SMFM 2021.

The study involved 1,219 pregnant women with singleton gestation who delivered between March and July, 2020, and who had a positive SARS-CoV-2 nucleic acid or antigen test, as diagnosed at one of 33 hospitals in the MFMU Network. COVID-19 was primarily asymptomatic (47 percent), while 27, 14, 8, and 4 percent of women had mild, moderate, severe, and critical disease, respectively, as per the National Institutes of Health severity classification. The women were followed up to 6 weeks postpartum while neonates were followed up until delivery hospitalization.

Women with severe/critical disease were generally older than those with moderate/mild or asymptomatic disease (age 30, 29, and 28 years, respectively; p_trend=0.006), and also had a higher median body mass index (32.3, 29.0, and 28.3 kg/m², respectively; p_trend<0.001). [SMFM 2021, abstract LB02]

Certain comorbidities were also more prevalent among women with severe/critical disease compared with those with mild/moderate or asymptomatic disease, namely asthma or chronic obstructive pulmonary disease (20.6, 17.0, and 8.8 percent, respectively; p_trend<0.001), pregestational diabetes (9.9, 3.6, and 2.9 percent; p_trend=0.002), chronic hypertension (11.3, 6.8, and 5.0 percent; p_trend=0.008), chronic liver disease (2.1, 0.4, and 0.2 percent; p_trend=0.01), and seizure disorders (3.5, 1.0, and 0.7 percent; p_trend=0.02).

The most common COVID-19 symptoms were cough (34 percent), dyspnoea (19 percent), and myalgias (19 percent).

Of the six maternal deaths that occurred, four were due to COVID-19 (0.3 percent).

Compared with women with asymptomatic disease, women with severe/critical COVID-19 had an elevated risk of Caesarean delivery (adjusted relative risk [adjRR], 1.57), hypertensive disorders of pregnancy (HDP; adjRR, 1.61), and postpartum haemorrhage (PPH; adjRR, 2.04). These risks were not higher in women with mild/moderate vs asymptomatic disease.

Venous thromboembolism incidence was higher in women with severe/critical disease than those with mild/moderate or asymptomatic disease (n=8, 1, and 0 respectively; p_trend<0.001).

The risk of preterm birth (<37 weeks) was also elevated among women with severe/critical vs asymptomatic disease (adjRR, 3.58), though not among women with mild/moderate disease. Foetal or neonatal death occurred in 6, 11, and 11 women with severe/critical disease, mild/moderate, and asymptomatic disease, respectively.   

Among women with live births, neonates born to women with severe/critical disease had lower mean birthweight (adjusted mean difference, -385 g vs asymptomatic disease), and a higher risk of admission to the neonatal intensive care unit (adjRR, 3.12).

The number of positive SARS-CoV-2 tests in neonates did not significantly differ according to disease severity (n=2, 3, and 7 in women with severe/critical, mild/moderate, and asymptomatic disease, respectively; p_trend=0.78).

“Overall, we saw a 1 percent rate of positive SARS-CoV-2 testing among the neonates during the delivery hospitalization,” said Metz.

The mean gestational age for COVID-19 infection was the late third trimester; as such, the study could not account for the risk of early pregnancy outcomes. Furthermore, many of the study sites were urban centres which limits generalizability to more rural settings, she continued.

“Our research shows that serious pregnancy complications appear to occur in women who have severe or critical cases of COVID-19 and not those who have mild or moderate cases,” noted Metz.

“This information helps us to counsel our patients more effectively. For pregnant women who have contracted a mild or moderate case of COVID-19, these findings can help to alleviate their fears that they are at an increased risk of having serious pregnancy complications due to the disease,” she said.