When it comes to COVID-19 and pregnancy, there is a lot we don't know. Now, a new report from the Centers for Disease Control (CDC) and a recent multi-center study on pregnant women with COVID-19 have provided a little bit more clarity.
Until recently, the effects of COVID-19 on pregnant women and birth results were a mystery because there just weren't many large studies on the topic. Pregnancy causes changes to the immune and respiratory systems, which has led to speculation that pregnant women might be more vulnerable to the disease.
Over the course of about six months, the CDC received more than 325,000 reports of women age 15 to 44 who had tested positive for SARS-CoV-2, the virus that causes COVID-19. Of those, more than 8,200 were pregnant.
When the CDC looked at how well these women did, they found good news and bad news. The good news is that pregnant women don't seem any more likely to die of COVID-19 than other groups. The bad news is that they do appear to be more likely to become extremely sick, and even become hospitalized, once they get infected.
Specifically, pregnant women were 5.4 times more likely to be hospitalized, 1.5 times more likely to be admitted to the ICU and 1.7 times more likely to be put on a ventilator. However, the CDC said that these results should be interpreted cautiously, because it's possible that some of these women were hospitalized due to issues related to their pregnancies and not necessarily COVID-19.
Despite worse symptoms seen in pregnant women with COVID-19, there was no difference in the risk of death between pregnant and nonpregnant women with COVID-19. Deaths occurred in 0.2% of both groups.
This finding roughly matches that of a recent peer-reviewed study published in the Obstetrics & Gynecology journal, which also reported similar news regarding COVID-19 pregnancy mortality rates.
Researchers at five New York City medical centers tracked more than 240 pregnant women in their third trimester with lab-confirmed COVID-19 infection. Upon admission to the hospital, around 60% of the women did not have any COVID-19 symptoms. The majority of this group remained asymptomatic throughout their delivery, with smaller numbers progressing to mild or severe COVID-19 symptoms, and one woman becoming critically ill.
There were no deaths, a positive yet unexpected result given the increased pregnancy death rates with other coronaviruses such as SARS and Middle Eastern respiratory syndrome (MERS).
"Our findings corroborate observational data that SARS-CoV-2 infection is associated with far less morbidity and mortality in pregnancy when compared to previous coronavirus epidemics, SARS-CoV-1 and MERS," said Dr. Rasha Khoury, M.D., M.P.H., a obstetrics & gynecology and women's health physician at Montefiore Health System and Albert Einstein College of Medicine.
However, a percentage of women in the study did experience serious symptoms. A little over a quarter had mild symptoms, 26% had severe COVID-19, and 5% were critically ill. Less than 10% were admitted to the ICU and nine were intubated. This includes one critically ill woman who suffered a heart attack due to respiratory failure caused by COVID-19 pneumonia.
Given the possibility that pregnant women might experience some of these severe problems, hospitals need to be prepared with adequate beds, ventilators and critical care providers, as patients, even those initially who are asymptomatic, can quickly progress to severe and critical symptoms, experts say.
"It is important to recognize the critical role of close observation regardless of initial lack of symptoms," Khoury said.
New York researchers also discovered an interesting trend in the rate of cesarean or c-section births. Across the country, overall about a quarter of women deliver through c-section. However, among the small group of women with COVID-19 who were studied in New York, a staggering 40% ended up giving birth via c-section.
The more severe her COVID-19 symptoms, the more likely a woman was to have a c-section. The same trend was seen with respect to preterm birth, defined as birth before 37 weeks. The more severe the COVID-19 symptoms, the higher the likelihood of preterm birth. Nevertheless, Khoury said, "nearly all neonates were unaffected, with uniformly good outcomes."
Obesity, defined as a BMI over 30, was the only condition associated with worse COVID-19 symptoms in Khoury's study. Age, race-ethnicity, insurance type or other underlying medical conditions were not associated with increased COVID-19 severity. However, that stands in contrast to data from the CDC which found that Hispanic and Black pregnant women might be disproportionately affected by SARS-CoV-2 infection during pregnancy.
Overall, there is a silver lining in these studies on pregnant women with COVID-19. Khoury notes that given asymptomatic spread, we still do not know the true prevalence of COVID-19, but he suggests that "the case fatality rate outside of pregnancy among women of reproductive age is likely as low as it is among pregnant women."
This is also borne out in the CDC data indicating that COVID-19 doesn't appear to be any more deadly in pregnant women than in nonpregnant women.
Nevertheless, additional studies investigating COVID-19 and pregnancy are needed.
"In a city and country where maternal and infant morbidity and mortality are disproportionately higher among communities of color, it is vital that we document and attempt to address the root causes of the disproportionate burden of SARS-CoV-2 infection and COVID-19 on these same communities," Khoury said.
Angela N. Baldwin M.D., M.P.H., is a pathology resident at Montefiore Health System in the Bronx and a contributor to the ABC News Medical Unit
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