Pregnant women should be prioritised for the flu vaccine as soon as it is available, according to the authors of a study showing they are more at risk of complications and more likely to end up in hospital than other people.
Women expecting a baby should also be given antiviral drugs as soon as they get the flu, says the paper published online today by the Lancet medical journal. Little is known about the possible ill-effects of the drugs on the foetus but scientists say their benefits are likely to be greater than the risks.
The research comes from the US, where six pregnant women died of swine flu complications between 15 April and 18 May. In that month, 34 confirmed or probable cases of swine flu were reported to the Centres for Disease Control and Prevention (CDC) from 13 states. Eleven of them were admitted to hospital.
The rate of admission to hospital is four times higher than in the general population, say the authors, Dr Denise Jamieson from the CDC's division of reproductive health in Atlanta and colleagues. That could be because doctors are more nervous about the effects if flu on pregnant women and are more likely to admit them, but the death rate among pregnant women is high.
"Although the decision to admit a pregnant woman is complex and might include considerations beyond simply the severity of disease, that a high proportion (greater than 10%) of influenza-related deaths in the USA have been in pregnant women is concerning," they write.
"In the previous influenza pandemics of 1918 and 1957, mortality seemed to be higher in pregnant women than in non-pregnant populations ... During the pandemic of 1957, 50% of deaths due to Asian influenza in Minnesota among women of reproductive age occurred in pregnant women."
None of the women who died had been given antiviral drugs promptly, within the first 48 hours of symptoms occurring, they write.
Once a vaccine is available, pregnant women will be a high priority, the authors say. However they are concerned that women may not come forward to be vaccinated because of fear of any effect on their baby. Few pregnant women choose to be immunised against winter flu.