Pregnancy and Flu: A Bad Combination

[indigo girl]

in a perspective, written by 3 cdc physicians (sonja a. rasmussen, denise j. jamieson, joseph s. bresee) and published in the cdc journal of eid article, pandemic influenza and pregnant women in february of 2008, we get this assessment of the historic impact of influenza on pregnant women.

although appropriate nonpregnant control groups were generally not available, mortality rates among pregnant women in the pandemics of 1918 and 1957 appeared to be abnormally high (5,7). among 1,350 reported cases of influenza among pregnant women during the pandemic of 1918, the proportion of deaths was reported to be 27% (5).

similarly, among a small case series of 86 pregnant women hospitalized in chicago for influenza in 1918, 45% died (6). among pregnancy-associated deaths in minnesota during the 1957 pandemic, influenza was the leading cause of death, accounting for nearly 20% of deaths associated with pregnancy during the pandemic period; half of women of reproductive age who died were pregnant

and during the opening months of the 2009 pandemic, we've seen a 4 to 6 fold increase in influenza-related hospitalizations among pregnant women compared to the rest of the population. sadly, we've received reports of numerous fatalities as well.

all of which has led doctors to advise that pregnant women receive antiviral treatment if infected, and be targeted for early vaccination when that becomes available.

one aspect of influenza infection during pregnancy that has been getting less attention, simply because the impact may not be as obvious or immediately apparent, are the effects prenatal exposure to the virus may have on the fetus.

there have been studies in the past that have linked such exposure to developmental problems, although the evidence is indirect. once again, the authors of the eid perspective weigh in:

although certain infections are well recognized to increase the risk for adverse pregnancy outcomes, the effects of maternal influenza infection on the fetus are not well understood. viremia is believed to occur infrequently in influenza (18), and placental transmission of the virus also appears to be rare (19).

however, even in the absence of fetal viral infection, animal studies suggest that adverse effects can still occur. prenatal influenza infection in the mouse has been associated with histopathologic changes in the brain (20) and behavioral alterations (21) in offspring. although influenza virus rna has not been detected in the fetal brain, these changes suggest that fetal effects could be secondary to the maternal inflammatory response, rather than the result of a direct viral effect (22).

in other words, it may not be so much the virus, but the immune response mounted by the mother, that can cause fetal damage. again they write:

associations between maternal influenza infection and childhood leukemia (23), schizophrenia (24), and parkinson disease (25) have been suggested by some studies. even if the influenza virus does not have a direct effect on the fetus, fever that often accompanies influenza infection could have adverse effects.

in april of this year, just days before the news of the novel h1n1 virus made the headlines, news of another retrospective study emerged reporting lower iq scores (on a population basis) among those born during the hong kong flu pandemic.

full commentary here: http://afludiary.blogspot.com/2009/10/pregnancy-flu-bad-combination.html

[HonestRN]

Oct. 1, 2009 -- H1N1 swine flu has killed 28 pregnant women in the U.S., raising the level of concern among obstetricians and CDC investigators.

The 28 women who died were among about 100 pregnant women who required intensive care because of severe H1N1 swine flu disease.

"Doctors around the country have never seen this kind of thing before," CDC respiratory disease chief Anne Schuchat, MD, said today at a news conference. "What we are seeing is quite striking."

The CDC has never before tracked the impact of flu on pregnant women. Although flu is a known risk both to a pregnant woman and to her fetus, it's not known for sure that H1N1 swine flu is any worse.

But that's the impression doctors are getting. Schuchat said that obstetricians at the CDC are in close contact with colleagues across the country.

"The obstetric caregivers here and the ones they are speaking with have rarely seen this kind of thing in practice," Schuchat said. "It has been very unusual."

Fortunately, there's a lot pregnant women can do.

Even though pregnant women are advised to avoid many medications, the flu drug Tamiflu is safe for pregnant women -- and should be given to them at the first sign of flu symptoms.

"Antiviral medicine can be a very important treatment for pregnant women who have respiratory symptoms or influenza-like illness," Schuchat said.

Moreover, the H1N1 swine flu vaccine and the seasonal flu vaccine -- the kinds that are given as a shot, not the kind given as a nasal spray -- are safe for use during pregnancy. Obstetricians and nurse midwives are urged to play a role.

"As the vaccine becomes available in appropriate formulations, we hope pregnant women and their caregivers will be taking advantage of it," Schuchat said. "We encourage caregivers to either vaccinate pregnant women or refer them to a place they can be vaccinated."

http://www.webmd.com/cold-and-flu/news/20091001/28-pregnant-women-dead-from-h1n1-swine-flu-in-us