Need another reason to get the flu shot if you're pregnant?
A study out this week shows that pregnant women with the flu who are hospitalized in an intensive care unit are four times more likely to deliver babies prematurely and four and a half times more likely to have a baby of low birth weight.
Researchers compared 490 pregnant women with the flu and 1,451 who did not have the flu. Sixty-four of the women with flu were so ill that they were admitted to a hospital ICU. The results appear in the journal Birth Defects Research.
The study also found that babies of the most seriously ill women were eight times more likely to have low Apgar scores, a measure of a baby's health in the minutes after birth. The test assesses the baby's color, heart rate, reflexes, muscle tone and breathing.
It's not clear exactly how being in the ICU may have affected the newborns, says Dr. Sonja Rasmussen of the University of Florida College of Medicine, one of the study's authors. She doesn't think the virus itself causes the problems, but concedes there's not enough information to draw firm conclusions.
More likely, Rasmussen believes, the problems arise because pregnant women with the flu are at "greater risk of getting pneumonia, of needing to be hospitalized and even being admitted to an intensive care unit," she says.
"When moms are in the ICU, they often need help breathing, they need a ventilator to breath for them, and it may be that there is some period of time where they aren't breathing well enough to get adequate oxygen to the baby," says Rasmussen.
For pregnant women in the study who were diagnosed with flu but who were able to stay home — and even those with flu who were hospitalized but not admitted to the ICU — there was no significant increase in risk for adverse health outcomes for their babies.
Rasmussen says it's possible that nutrition plays a role in the newborns' problems. "When you're having trouble breathing, you have trouble eating and it may be that mom wasn't getting good nutrition during her time in the ICU."
Rasmussen says the findings underscore the importance of pregnant women receiving the influenza vaccine and getting prompt treatment with antiviral medications.
Prior to the 2009 pandemic, only about 20 to 30 percent of pregnant women got the flu vaccine. After doctors and health professionals strongly urged vaccination, the rate increased to about 50 percent.
"Since then, flu vaccine rates have stagnated" as memories of the pandemic have faded, says obstetrician-gynecologist Dr. Denise Jamieson of Emory University School of Medicine. The "vast majority" of pregnant women should be vaccinated, she says.
Jamieson says the reasons patients give for not getting the vaccine are numerous. Some say they've just never had the flu before and don't expect to get it while pregnant, which "doesn't mean they'll avoid the flu this season," she says.
Others say they got the vaccine in the past and it made them sick. That's unlikely, Jamieson says. The flu vaccine does not contain active virus, but rather is a "killed" virus vaccine, and therefore not infectious.
Still other patients worry the vaccine might not be safe for their developing baby. That's another fallacy, Jamieson says.
"This is a vaccine we have been giving in pregnancy for many decades and there is no indication of any problems," she says. "It's a safe vaccine and we know more about this vaccine than any other vaccine in pregnancy."
And, importantly, it has huge benefits which include "safeguarding pregnant women and their infants against what could be devastating complications of influenza," she says.
When women get vaccinated, they make antibodies to fight the virus. Those antibodies can cross the placenta and protect the baby from severe illness, which is important, Jamieson says, because infants' immune systems are still developing and they can't be vaccinated until they are 6-months-old.
So the vaccine "provides some protection from birth up to six months of age," she says.
And it's never too late or too early to get the vaccine, according to Jamieson. Pregnant women should get their flu vaccine as "soon as it's available," she says.
ARI SHAPIRO, HOST:
New research finds that pregnant women who get so sick from the flu they're hospitalized in an intensive care unit are at high risk of having a baby with health problems. NPR's Patti Neighmond reports on the study in the journal Birth Defects Research.
PATTI NEIGHMOND, BYLINE: Women's immune systems change when they get pregnant, and they're more susceptible to complications from the flu. Dr. Sonja Rasmussen with the University of Florida College of Medicine.
SONJA RASMUSSEN: That means they're more at risk of getting pneumonia. They're more at risk of needing to be hospitalized and even being admitted to an intensive care unit.
NEIGHMOND: As a pediatrician, Rasmussen wanted to know how this might affect newborns. She compared 490 pregnant women with the flu to more than 1,400 who did not have the flu. She found those who got severely ill from the flu and were hospitalized in intensive care units were significantly more likely to have babies with health problems.
RASMUSSEN: More likely to deliver their babies too early - prematurely - more likely to have a baby of low birth weight and were more likely to have babies with low Apgar scores. And that's those scores that tell how a baby's doing after birth.
NEIGHMOND: Measuring things like heart rate, reflexes and breathing. Women who got the flu but were able to stay at home and even those who were hospitalized but not admitted to the ICU had no increased risk of health problems for their newborns. Rasmussen says it's not clear how being in the ICU affected newborns. She doesn't think it's the flu virus itself.
RASMUSSEN: When moms are in an intensive care unit, they oftentimes are needing help with breathing. They're needing to have a ventilator breathe for them. So it may be that they had some period of time that they weren't getting good oxygenation - you know, weren't breathing well enough to get good oxygen to the baby.
NEIGHMOND: And when patients have trouble breathing, they're likely to have trouble eating, which could mean they weren't getting adequate nutrition. Rasmussen says the findings highlight the need for pregnant women to get vaccinated against the flu. OB-GYN Dr. Denise Jamieson with Emory University School of Medicine says only about half of all pregnant women today get the vaccine.
DENISE JAMIESON: We've been recommending the vaccine since the 1960s, yet we have not been able to increase the vaccination rates to protect most women.
NEIGHMOND: And their babies. Jamieson says some of her patients think the vaccine will make them sick. It can't, she says, because it's an inactive killed virus. Others think it's not safe. Not true, says Jamieson.
JAMIESON: This is a vaccine that we have been giving in pregnancy for many decades, and there's no indication that there are specific concerns in pregnancy. It's a safe vaccine.
NEIGHMOND: When women get vaccinated, they make antibodies to fight the virus. Those antibodies can cross the placenta and protect the baby, which is important, says Jamieson, because infants' immune systems are just beginning to develop. And they can't get the flu vaccine until they're 6 months old. Patti Neighmond, NPR News.
(SOUNDBITE OF YASUAKI SHIMIZU SONG, "108 DESIRES") Transcript provided by NPR, Copyright NPR.