About twice as many pregnant women as usual got flu vaccines last year during the H1N1 swine flu pandemic, most because their doctors urged them to do so, federal government researchers reported on Thursday.

But still only about half of the women pregnant during the flu season got immunized, even though they are much more likely to become severely ill, die or lose their babies if they come down with the flu, the U.S. Centers for Disease Control and Prevention found.

Ironically, many of the women who did not get flu vaccines said they were afraid for their own health or the health of their babies, the CDC found.

The American College of Obstetricians and Gynecologists and the CDC’s Advisory Committee on Immunization Practices both strongly recommend that pregnant women get influenza vaccinations to protect themselves and their babies.

But historically, only 24 percent of those pregnant during the 2007-2008 influenza season got vaccinated and just 11 percent did the next year.

During the swine flu pandemic, virtually everyone in the United States was advised to get two vaccines - the seasonal influenza vaccine and a separate one for H1N1 swine flu.

Pregnant women were, as usual, named as a priority group - especially after early information suggested pregnant women were especially susceptible to H1N1.

CDC researchers looked at surveys of more than 16,000 pregnant women in 10 U.S. states.

They found that in these 10 states, just over 50 percent of pregnant women received a seasonal flu vaccine and 46 percent got a swine flu vaccine.

More than 60 percent of pregnant women whose doctors recommended the H1N1 vaccine got one, versus just under 6 percent who said they were not offered one. More than 67 percent said their doctors offered a seasonal vaccine and 75 percent were offered H1N1.

“With a novel virus, 2009 H1N1, the role of health-care providers in reassuring pregnant women might have been critical because of patient concerns regarding the new vaccine,” the CDC wrote in its weekly report on death and illness.

“Among 2,290 women who received the 2009 H1N1 vaccination, 50.9 percent reported receiving it at the office of their obstetrician/gynecologist, and 25.7 percent received it at a health department or community clinic,” the report adds.

Of the women who did not get an H1N1 vaccine, more than 60 percent said they were worried about their own safety or that of their unborn babies.

U.S. health officials are struggling to understand why Americans in general do not get flu vaccines. The CDC estimates virtually all the 115 million seasonal flu vaccine doses got used last season, but of 162 million H1N1 swine flu doses distributed, only 80 million were used.

In March, researchers reported that pregnant women in Australia and New Zealand who had pandemic H1N1 flu were 13 times more likely to become critically ill and be admitted to hospitals [ID:nLDE62H093].

In October, a study confirmed that newborn babies whose mothers got a flu shot while pregnant were less likely to get the flu or to be admitted to the hospital with a respiratory illness in the first six months of life [ID:nN04694658]

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By Maggie Fox, Health and Science Editor

WASHINGTON