A stark reminder about how deadly the new H1N1 virus can be. During a news briefing Thursday, U.S. health officials said the virus has hit pregnant women especially hard.

“The CDC is aware of about 700 cases of 2009 H1N1 in pregnant women since late April or early May,” Tom Skinner, a spokesman for the Centers for Disease and Control and Prevention told FOXNews.com. “There have been about 100 pregnant women admitted to intensive care units and there have been 28 pregnant women who have died from 2009 H1N1.”

Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases at the CDC said these numbers “are really upsetting” and urged pregnant women to get the seasonal flu vaccine and the H1N1 vaccine.

“It’s safe and effective and we think it’s important to get this (H1N1) vaccine out as soon as it’s available,” Schuchat said at the briefing.

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Dr. Manny Alvarez, head of maternal fetal medicine at Hackensack University Medical Center in Hackensack, N.J., and managing editor of health at FOXNews.com, said there are two fundamental risk factors that pregnant women face when they get the flu.

“First, pregnant woman have an immune system that is slow – it’s like their immune system is on standby – and it’s not as reactive as a non-pregnant person’s,” Alvarez said. “And because of that, viruses, especially flu viruses of any sort can create a very severe infection.”

The second challenge women face is as the baby grows inside the womb, the anatomy of a woman’s chest changes.

“Their whole respiratory volume changes,” Alvarez said. “So if they get a secondary infection, such as pneumonia after the flu, it makes it very challenging and problematic for doctors to get airflow back into the lungs.”

Until now, the CDC has never really looked closely at influenza in pregnant women.

“It’s hard to say if what we’re seeing now is out of the ordinary compared to the how pregnant women have been affected by the seasonal flu,” said Tom Skinner, CDC spokesman. “But what we are hearing from physicians around the country is that they’ve never seen pregnant women impacted like this by the flu… and so we’re going to have to some more research to understand if this is a unique situation to the this new virus.”

Alvarez, who treats high-risk pregnancy patients, said at this time he’s making sure all of his patients know about the dangers of the flu.

“Just yesterday, a patient informed me that her son had the flu, so we immediately began administering antiviral medications, until the new vaccine becomes available.”

Unlike other patients, pregnant women cannot get the nasal spray FluMist, Skinner said.

“They must get the injectable vaccine, which will hopefully be available starting next week,” he added.


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