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Pregnancy raises risk of critical illness with swine flu

Pregnancy raises women's risk of critical illness by 13 times

OnMedical staff

Friday, 19 March 2010

Pregnant women who caught swine flu were 13 times more likely to be admitted to hospital with critical illness than women who had swine flu while not pregnant, according to research published on bmj.com.

The authors of the study conclude that 11% of mothers and 12% of babies died as a result of being admitted to intensive care with swine flu. However they emphasise that given the small numbers included in their research, there are limits to the conclusions that can be drawn from their results.

It was already known that pregnant women are at a higher risk of developing influenza complications, and this study was designed to assess the outcome for women admitted with swine flu to intensive care units (ICU) in Australia and New Zealand in winter 2009. The recent swine flu pandemic was the first “to occur in an era of modern obstetric and intensive care management”, say the authors, led by Dr Ian Seppelt from the Australian and New Zealand Intensive Care (ANZIC) Influenza Investigators in collaboration with the Australasian Maternity Outcomes Surveillance System.

Dr Seppelt and colleagues examined data on women admitted to an ICU with swine flu in Australia or New Zealand between 1 June and 31 August 2009. During that time, 209 women aged 15-44 years were admitted to an ICU with confirmed swine flu. Sixty-four (30.6%) of these women – 57 in Australia and seven in New Zealand – were either pregnant or had recently given birth.

They found that women who were more than 20 weeks pregnant were 13 times more likely to be admitted to an ICU than non-pregnant women who had swine flu. Forty-four (68.7%) of the women required mechanical ventilation and of these, nine women (14.1%) needed further assistance to help oxygen reach their heart and lungs.

Overall seven (11%) of the mothers and seven (12%) of the babies died and Dr Seppelt argues that “although a mortality of 11% seems low when compared to usual outcomes of respiratory failure in intensive care … a maternal morality of 11% is high when compared with any other obstetric condition.”

None of the women in this study had been immunised against seasonal flu despite recommendations that pregnant women should be immunised.

In an accompanying editorial, Dr Stephen Lapinsky from the Mount Sinai Hospital in Toronto, applauds the research team for their foresight and planning in investigating how swine flu affected pregnant women and those who recently gave birth.

He says the study “provides detailed data to enhance our understanding of maternal risk as well as the maternal and neonatal outcome”.

Meanwhile, the Department of Health is urging people travelling to the southern hemisphere, including the football World Cup in South Africa, to be vaccinated against swine flu to prevent them from catching the virus during the coming winter flu season and bringing it back to the UK.

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