Getting your flu shot is even more critical when you are pregnant or have recently given birth, a University of Arizona College of Medicine – Phoenix faculty member warns.

“Influenza is more dangerous in pregnant women than other women because the changes in the immune system while you are carrying your child,” said Maria Manriquez, MD, who is also an obstetrics/gynecological physician at Maricopa Medical Center. “That’s why it is imperative that pregnant women get their flu shot now that we are entering the season.”

The first Arizona flu case was reported earlier this month.

According to the federal Centers for Disease Control and Prevention, influenza is five times more likely to cause severe illness in pregnant women than in women who are not pregnant. Pregnant women undergo changes in their immune systems, heart and lungs while pregnant making them more susceptible. Pregnant women with the flu also increase their risk of premature labor and delivery, the CDC says.

Vaccination during pregnancy has been shown to protect both the mother and child up to six months of age. Flu vaccines are not given to children until six months after they are born.

“Millions of pregnant women have received flu shots over the last several years and it has not been shown that it did any harm to mothers or babies,” Dr. Manriquez said. “In fact, it likely saved many of these women from getting sick or passing on sickness to their infant.”

The CDC said women at any point in their pregnancy can receive a flu shot and should get the vaccine rather than the nasal spray. Physicians also say women should get inoculated after they have given birth, even if they are breastfeeding, and can receive either type of vaccine.