Other findings in the review:

In the first four months of the H1N1 flu outbreak this spring, pregnant women were hospitalized at four times the rate of other healthy adults infected with the virus, according to the CDC. Pregnant women made up 13 percent of all H1N1 deaths during that period, and most of the women who died were previously healthy. Pregnant women do not get infected with the flu more often than other adults, but they develop more serious complications and more often. Pregnant women with underlying conditions such as asthma or diabetes are at even higher risk for complications. During the 1918 Spanish flu pandemic, of the 1,350 flu-infected pregnant women who were studied, half developed pneumonia, and more than half of those who did so died, with most deaths occurring during the third trimester. During the 1957 pandemic, nearly half of all women of childbearing age who died of the flu were pregnant. Eleven clinical studies closely followed pregnant women and/or their fetuses after vaccination and found no evidence of harmful side effects in either the mother or the fetus. The Vaccine Adverse Event Reporting System database, a national repository of self-reports of adverse vaccine effects, showed 26 reports of adverse effects between 2000 and 2003, a period during which 2 million pregnant women were vaccinated against the flu. Of the 26 reports, six had to do with wrongly administered vaccine without any negative consequences; nine reports described brief injection site tenderness; eight involved systemic symptoms, such as malaise and fever; and three were miscarriages. Investigators point out that these are self-reported events and do not establish any evidence of cause and effect either with respect to either miscarriage or side effects.

Source: Johns Hopkins Medical Institutions