Pregnant women are usually at a high risk for complications when they get the seasonal flu, but they have been affected much more by the H1N1 strain that emerged in the spring, experts say.

Compared to the general population, a greater proportion of pregnant women who have been infected with H1N1 flu have been hospitalized, according to the federal Centers for Disease Control and Prevention. In addition, 6 percent of fatal H1N1 flu cases have been in pregnant women, while only about 1 percent of the general population is pregnant at a given time.

Dr. James Sabetta, director of infectious diseases at Greenwich Hospital, said the physical and hormonal changes that occur during pregnancy create the greater risk. Lung capacity decreases as a woman's abdomen gets bigger, and her heart rate goes up. Pregnancy also alters the immune system.

"They don't do as well fighting infections," Sabetta said.

As a result, pregnant women are being encouraged to take the new H1N1 vaccine that is slated to arrive next month.

The vaccine will be distributed first among those in the high-risk group, which includes pregnant women, young children, caregivers for children less than 6 months old, health care workers and children and teens with chronic medical conditions.

William Gerrish, a spokesman from the state Department of Public Health, said the state has been recruiting health care providers, including obstetricians, to administer the vaccine, and the

state has so far registered more than 1,500 providers. It sent letters to the Connecticut chapter of the American College of Obstetricians and Gynecologists, encouraging doctors to educate their pregnant patients on the risks associated with swine flu.

Gov. M. Jodi Rell said Thursday that Connecticut is expected to begin receiving the H1N1 vaccine as early as the first week of October. By mid-October, the state is expected to receive more than 500,000 doses, with subsequent shipments of 200,000 per week. There has been no word on how much Greenwich will receive.

Gerrish said the initial supply the state is receiving will be the FluMist nasal spray vaccine, which is made with live, weakened flu vaccine and is not approved for use by pregnant women. They should get the flu shot made from fragments of dead influenza virus, according to the CDC.

Riverside obstetrician Russell Turk said he has heard rumors about the safety of the new vaccine, and worries about developing allergic reactions or Guillain-Barre syndrome, an autoimmune disorder that affects the peripheral nervous system.

"I'd say in the few weeks I have before it actually does come out, I'm still spending some time examining the safety profile," Turk said. "I'm not necessarily expecting to find something, but I want to be in a situation, when these questions are asked of me, that I'm confident I thoroughly looked into it."

Turk has seen how the H1N1 virus can be particularly risky during pregnancy. While he was on call recently at Stamford Hospital, there was a pregnant woman with the flu strain admitted to the intensive care unit. Turk said he will likely advise his patients to get vaccinated.

"It appears, especially for the pregnant population, that it's going to be a fairly clear recommendation," Turk said.