(CBS) -- Diana Barron Gonzalez says her best friend, Maria Paniagua was seven months pregnant when she caught the flu.
She says the illness forced doctors to hold off performing a cesarean section as the heartbeat of Paniagua's unborn child faded. The California mother of four survived. Her baby did not.
"If they would have operated on her with the cesarean, they could have lost the mother or the baby or both," Gonzalez says.
At least 37 children have been killed by the flu this season.
"We've seen kids are really making up the predominant amount of influenza-like illness. And they're taking that back to school, it's getting transmitted there, and I think that's really what's driving a lot...the visits to the outpatient clinic right now," says Daniel Jernigan, director of the CDC's Influenza Division.
Schools across the country are racing to contain the virus. At least six school districts in Oklahoma closed because too many staff and students called out sick. And in Gulf County, Florida, more than 20% of students were absent because of flu-like symptoms.
"11 in this building alone – of the instructional staff – are out, either sick or tending to their sick child," said Gulf County Schools superintendent Jim Norton.
Everyone should get a flu shot and pregnant women are no exception to the rule. The CDC says it's not only safe for expecting mothers, but can also help protect infants from the virus for several months after they're born.