Researchers found that half of the 600 participants in the study had symptoms after three weeks, while 25% reported symptoms after eight weeks.
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Unlike most COVID cases, only 12% of the pregnant participants reported fever as their first symptom, the authors found.
The most common first symptoms in the study included a cough and a sore throat, which 20 percent and 16 percent of participants reported respectively.
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It took an average of 37 days for symptoms to ease.
Vanessa Jacoby is a UCSF doctor and senior author of the study.
"One of the main takeaways is, we want pregnant people and their providers to recognize that you don't need to wait for a fever to consider COVID-19 in pregnancy," Jacoby says, "The most common symptoms, again, were cough and sore throat."
The study launched on March 22.
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Once completed, researchers will have substantial data on more than 1,300 participants, giving them a much better idea of the virus's impact on pregnant women.