Study - Women in the later stages of pregnancy who have swine flu have a substantially higher risk of becoming critically ill - NZ author urges vaccination

[Sally Furniss]

Updated at 5:01pm on 19 March 2010

Women in the later stages of pregnancy who have swine flu have a substantially higher risk of becoming critically ill than other women of the same age.

That's the conclusion of a study published on Friday in the British Medical Journal, or BMJ.

The study is based on details gathered from intensive care units in New Zealand and Australia from June to September last year.

It says that compared with non-pregnant women of child-bearing age, those who were pregnant or had just given birth, and had swine flu were at greater risk of becoming critically ill.

The risk for women 20 or more weeks pregnant was 13 times higher than for non-pregnant women of similar age.

Pregnant women are eligible for a free flu vaccination this winter, because of the risk.

One of the study authors, Dr Colin McArthur, head of critical care medicine at Auckland City Hospital, is urging them to have it.

Copyright ? 2010 Radio New Zealand

http://www.radionz.co.nz/news/stories/2010/03/19/1247f8624e02

[tetano]

Re: Study - Women in the later stages of pregnancy who have swine flu have a substantially higher risk of becoming critically ill - NZ author urges vaccination

Published 18 March 2010, doi:10.1136/bmj.c1235
Cite this as: BMJ 2010;340:c1235
Editorials
Critical illness as a result of influenza A/H1N1 infection in pregnancy

Mortality is high, but lower than expected

The 2009 pandemic influenza A/H1N1 virus has a predilection for the lower respiratory tract. In some cases, infection results in a pneumonitis and severe acute respiratory distress syndrome, which can be difficult to manage despite advanced ventilatory techniques. The effects of H1N1 infection on pregnant women became cause for concern early in the course of the current pandemic because of initial experience1 and data from previous pandemics.2 3 4 In the linked study (doi:10.1136/bmj.c1279), the ANZIC influenza investigators provide a detailed analysis of a cohort of pregnant women who developed critical illness as a result of pandemic H1N1 infection in 2009.5

During pregnancy changes occur to a woman?s immune system to facilitate tolerance of paternally derived fetal antigens. While the pregnancy is recognised by the maternal immune system, the immune response is characterised by an altered TH1-TH2 (type 1-type 2 T helper cell) balance. The maternal immune response favours humoral immunity (TH2 response), and suppresses cell mediated immunity (TH1 response), which could be harmful to the fetus.6 This altered immune response may predispose pregnant women to increased severity of certain infections, including viral pneumonitis. Pregnant women have an increased risk of being admitted to hospital for pulmonary complications of seasonal flu, and the risk increases during later stages of gestation and with associated comorbidity,7 but flu related maternal mortality outside of a pandemic is low. In contrast, in previous flu pandemics, maternal mortality has been higher than that seen in the non-pregnant general population. During the 1918-9 pandemic, maternal mortality was reported to be 27% in a review of 1350 cases,2 and as high as 50% in an indigent population.3 In the 1957-8 epidemic, half of the women of child bearing age who died were pregnant.4

Public health agencies in the United States reported outcomes of pregnant patients with 2009 H1N1 infection from early on in the pandemic. An initial report in May 2009 from the Centers for Disease Control and Prevention (CDC) described 13 cases; three of these women were admitted to hospital, and one died.1 A more detailed report from the CDC published in August 2009 described 34 cases; six of these women died, and the hospital admission rate was estimated to be four times higher than that of the general population.8 A study from California that described 102 obstetric patients found that mortality was 8%, and it showed that early antiviral therapy improved the outcome.9 Compared with the usual maternal mortality from all causes in the United Kingdom of less than 100 women per year (0.014% of pregnancies), maternal mortality from H1N1 infection is strikingly high.10

The Australian and New Zealand Intensive Care (ANZIC) Influenza Study Investigators carried out a detailed inception cohort study of all critically ill patients in Australia and New Zealand with 2009 H1N1 infection,11 and also specifically looked at the pregnant and postpartum subgroup.5 Sixty four pregnant woman were admitted to intensive care for H1N1 infection in Australia and New Zealand between 1 June and 31 August 2009. This was around a seven times higher risk of admission compared with non-pregnant women of childbearing age. Forty four (69%) pregnant women admitted to intensive care needed mechanical ventilatory support, and nine women (14%) received extracorporeal membrane oxygenation.

The linked population based cohort study provides detailed data to enhance our understanding of maternal risk as well as maternal and neonatal outcome. Outcomes are better than in previous pandemics, but the results are still worrying. Mortality for these critically ill pregnant women was 11% (33% for those requiring extracorporeal membrane oxygenation) and fetal loss was 12%. Although this is a high figure for young pregnant women, it is a good outcome for a cohort of patients with severe acute respiratory distress syndrome. The study also confirmed that previously reported risk factors for severe disease?including indigenous population status, presence of comorbidity, and obesity?are associated with a worse outcome.

Pregnant women, particularly those in the second half of their pregnancy, have a greatly increased risk of developing severe pneumonitis associated with pandemic H1N1. Despite evidence of an increase in maternal mortality after infection with H1N1, in the later phases of the pandemic its effect on pregnant women has been less than was initially anticipated. This may be attributable to worldwide recommendations for pregnant women to be vaccinated against the 2009 H1N1 strain and advice to facilitate early access to antiviral treatment for pregnant women with symptoms of flu.12

Cite this as: BMJ 2010;340:c1235

Stephen E Lapinsky, associate professor of medicine

1 Interdepartmental Division of Critical Care, University of Toronto, Toronto, ON, Canada

http://www.bmj.com/cgi/content/full/340/mar18_3/c1235

[tetano]

Re: Study - Women in the later stages of pregnancy who have swine flu have a substantially higher risk of becoming critically ill - NZ author urges vaccination

Pregnant or postpartum women were seven times more likely than other women of childbearing age to be admitted to intensive care if they had the H1N1 pandemic flu, Australian and New Zealand researchers said.

The risk rose to 13 times at 20 or more weeks of gestation, according to Ian Seppelt, MB BS, BSc(Med), of Nepean Hospital in Sydney, and colleagues.

And 11% of those admitted to the ICU in the two countries died, the researchers reported online in BMJ.

The outcomes are strikingly worse than those usually seen. Seppelt and colleagues noted that between 1997 and 2005 in Australia, any form of infection led to 24 maternal deaths -- or just 1.1 deaths per 100,000 births.

But only one of those deaths was due to flu, they said.

In contrast, there were seven deaths among 64 pregnant or postpartum women admitted to the ICU with confirmed H1N1 pandemic flu between June 1 and Aug. 31 last year, they said.

The investigators studied outcomes for all women admitted to the 187 intensive care units in the two countries. They found that, during the study period:

* 209 women of childbearing age (defined as 15 to 44 years) were admitted to an ICU with confirmed 2009 H1N1 infection -- 57 in Australia and seven in New Zealand.
* 64 (or 31%) were either pregnant or postpartum. When flu symptoms started, 10 were at less than 20 weeks' gestation, 49 at 20 weeks' or more, and five had given birth.
* By the time of admission, 22 women were postpartum, two had miscarried, 14 gave birth during their stay in the ICU, and 26 were discharged still pregnant and later delivered.
* The proportions yielded a relative risk of 7.4 for admission to intensive care for pregnant or postpartum women. The relative risk was 13.2 if they were at 20 weeks or more of gestation.
* Of those admitted, 44 needed mechanical ventilation, including nine treated with extracorporeal membrane oxygenation.
* There were 60 births after 20 weeks' gestation, including four stillbirths and three infant deaths.
* 22 of the liveborn babies were preterm, and 32 were admitted to a neonatal ICU.

The authors concluded that pregnancy is a risk factor for critical illness if a woman becomes infected with the H1N1 pandemic flu.

But they cautioned that the numbers in the study are small, which may mean that "incidence, infection rate, and virulence of influenza infection may be different at other locations and at different stages of the pandemic."

The outcomes "are better than in previous pandemics, but the results are still worrying," according to Stephen Lapinsky, MB BCh, of the University of Toronto.

In an accompanying editorial, Lapinsky noted that mortality rates among pregnant women were as high as 50% in some populations during the 1918-19 pandemic. And, he added, in the 1957-58 epidemic, half of the women of childbearing age who died were pregnant.

The 11% death rate is high for young pregnant women, he said, although it's actually "a good outcome for a cohort of patients with severe acute respiratory distress syndrome."

The effect of the H1N1 pandemic on pregnant women is less than had been anticipated based on early evidence, he said, perhaps because of recommendations for early antiviral therapy and vaccination.

http://www.medpagetoday.com/InfectiousDisease/SwineFlu/19135

[kiwibird]

Re: Study - Women in the later stages of pregnancy who have swine flu have a substantially higher risk of becoming critically ill - NZ author urges vaccination

Swine flu blamed for rise in pregnancy deaths
By Alice Neville and Joseph Barratt 4:00 AM Sunday Mar 21, 2010 Facebook

Pregnant women are being encouraged to have the flu vaccine. Photo / Hawkes Bay TodayThe swine flu virus is being blamed for a leap in the number of pregnant women dying in New Zealand and Australia.

New research has found 11 per cent of pregnant mothers admitted to intensive care in Australia later died of swine flu, or H1N1. Twelve per cent of their babies also died.

The study, published in the British Medical Journal this week, comes from analysis of intensive care records during last winter.

Of 209 women of child-bearing age placed in intensive care with swine flu, 64 were pregnant or had recently given birth. Seven of those died, including four in New Zealand.

Researcher Claire McLintock, from Auckland Hospital, said the small numbers in the survey meant they could not draw wide-ranging conclusions about the high number of New Zealand women who died.

McLintock said: "There's normally very few deaths in pregnancy, only a handful each year. Worldwide there will be a big spike in pregnancy-related deaths for 2009 because of H1N1."

None of the 64 pregnant women had received the flu vaccine, despite it being free and encouraged for pregnant women.

Christchurch woman Melissa McDonnell was six months' pregnant when she contracted swine flu.

She said she was unsure what effect the virus would have on her and her unborn baby.

"No one knew what it was going to be like for pregnant women.

"I didn't want to take the Tamiflu vaccine; but if I had broken into a serious fever, I would have."

McDonnell said eating well and lots of sleep helped her through. She now has a healthy 5-month-old daughter, Georgia.

Norma Campbell from the New Zealand College of Midwives was not surprised by the findings.

"Certainly we do know pregnant women are far more at risk and it would seem to be they are later in pregnancy.

"All through history women who are pregnant are more at risk of influenza and H1N1 seems to be particularly so."

Almost 15,000 people died during the 2009 swine flu pandemic. Nineteen New Zealanders are believed to have been among them.

By Alice Neville and Joseph Barratt

http://www.nzherald.co.nz/medicine/news/article.cfm?c_id=255&objectid=10633381