Pregnancy puts a lot of stress on a woman’s physiology. So it is not surprising that pregnant women are at increased risk from pandemic flu. One study reported that 25% of pregnant women who became infected with pandemic influenza in 1918 died (Mortimer, 2006). In the flu pandemic of 1958, pregnant women made up half of all the deaths among women of reproductive age in Minnesota (Freeman and Barno, 1959). We don’t know what the case fatality rate for pregnant women is from the current pandemic because we don’t know how many pregnant women have been infected. However, we do know that the risk of death for pregnant women is much higher than average. Although pregnant women make up only 1% of the US population, they have contributed to 6% of the deaths. In poorer countries, the death rate of pregnant women may be even higher.
The risks to unborn young are also substantial. Pregnant women infected with pandemic H1N1 appear to be at increased risk of spontaneous abortion. In the pandemic of 1958, there is some evidence of increased incidence of birth defects. There may be long term effects on the fetus as well. A recent study suggested that people who had been exposed to the 1918 pandemic virus while in the womb were 20% more likely to get heart disease (Mazumder et al. 2009).
The best way for pregnant women to stay safe is to avoid infection with the virus. This can be done by avoiding contact with infected people and by getting vaccinated. Although thimerosol has not been shown to cause any harm, thimerosol-free vaccine is available for pregnant women. Pregnant women should receive inactivated virus, the “shot”, not the attenuated virus “Flumist”. Because of their increased risk, pregnant women are at the top of the priority list for receiving vaccine. They may contact their doctor to find out where and when they can receive vaccine.
If a pregnant woman becomes ill, it is important that she receive rapid treatment for the best outcome. The antiviral drug Tamiflu has been approved for use by pregnant women. It is most likely to work if given within 48 hours after symptoms begin but may be effective after that. If a pregnant woman’s lungs are damaged, she may need to be put on a ventilator. Because some pregnant women do not survive this experience, there have been a number of babies who were delivered by Caesarean section while their mothers were in medically induced comas.
You can find a list of pregnant women who have died of pandemic flu at PFI_Forum on this thread (started and organsied by VA_MOM): US Deaths of Pregnant Women. Warning, this is very difficult reading. You can find video reports about pregnancy and pandemic flu at the PFI_Main Pregnancy page. Some of these can also be difficult to watch.
Local Government Board, 48th Annual Report 1918–1919. Supplement containing the report of the medical department. London: Her Majesty’s Stationery Office; 1919. p. 16.
Mazumder et al. (2009) Lingering prenatal effects of the 1918 influenza pandemic on cardiovascular disease. J. Dev. Origins Health Dis.
Jamieson et al. (2009) H1N1 2009 influenza virus infection during pregnancy in the USA. Lancet. 374:451-8
Mortimer (2006) Influenza-related Death Rates for Pregnant Women. Emerg Infect Dis.
Freeman and Barno (1959) Deaths from Asian influenza associated with pregnancy. Am. J. Obstet. Gynecol. 78:1172-1175.
2009 H1N1 Influenza Vaccine and Pregnant Women: Information for Healthcare Providers. CDC, November 2, 2009.