News

Deadly swine flu risk to pregnant women uncovered in landmark study


19 March 2010

Researchers have warned of the potential risk to pregnant women of complications from swine flu ahead of the influenza season, which kicks off during the Easter period.

A study to be published in the British Medical Journal (BMJ) on Friday, 19 March, has found 11 per cent of pregnant women admitted to intensive care units (ICU) with 2009 A/H1N1 (swine flu) died, with 12 per cent of babies born to them dying from complications. None of the mothers had been immunised against seasonal flu.

The research is the first of its kind to study this area of the 2009 swine flu pandemic, the first such outbreak to occur in the era of modern obstetric and intensive care management.

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, assessed the data relating to all women with swine flu who were pregnant or who had given birth in the last 28 days and were admitted to an ICU in Australia or New Zealand between 1 June and 31 August 2009.

During the study period, 209 women of child-bearing age (15 to 44) were admitted to an ICU with confirmed swine flu. Sixty-four of these (30.6 percent) were either pregnant or had recently given birth and 57 were admitted to an ICU in Australia and seven to an ICU in New Zealand.

Dr Seppelt said the study found women with swine flu who were more than 20 weeks pregnant were 13 times more likely to be admitted to hospital with a critical illness.

"It has already been established that pregnant women are at a higher risk of developing influenza complications," Dr Seppelt said.

"The effects of influenza during pregnancy have been noted in previous pandemics, particularly the increased morbidity in pregnant women compared with the general population.

"Overall, seven (11 percent) of the mothers and seven (12 percent) of the babies died and although a mortality of 11 percent seems low when compared to usual outcomes of respiratory failure in intensive care, a maternal morality of 11 percent is high when compared with any other obstetric condition. Forty-four (68.7 percent) of the women had to be put on ventilators to assist with breathing and of these, nine women (14.1 percent) needed further assistance to help oxygen reach their heart and lungs.

"It is of great concern that none of the women in the study had been immunised against seasonal flu despite widespread recommendations that they should be immunised against swine flu.

"With strong predictions that swine flu will re-surface and amount for up to 75 percent of flu cases in 2010, we cannot stress enough how important it is for pregnant women to be immunised.

"The Australian flu season officially starts in May and we are encouraging expectant mothers to be prepared."


Media inquiries: Rachel Gleeson, 0403 067 342 or rachel.gleeson@sydney.edu.au

Research contact: Dr Ian Seppelt, Senior Staff Specialist, Department of Intensive Care Medicine, University of Sydney, 0412 595 647 or seppelt@med.usyd.edu.au