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Going into the pandemic of 2009 one of the earliest dilemmas facing health officials and doctors was what to advise pregnant women regarding the use of antiviral medications.
The simple fact is, for most modern medicines, there is simply insufficient information available regarding their safety during pregnancy. Clinical trials using pregnant women are seldom performed because of the potential danger to the fetus.
As such, the FDA classifies many medications as Category C (insufficient information available to assess their potential risk and benefit during pregnancy). Animal studies are performed, of course, but they don’t always predict with accuracy a drug’s effects on humans.
Pregnancy, however, has long been recognized as a serious risk factor during a pandemic.
Researchers know that during the 1918 pandemic an abnormally high number of pregnant women died from the influenza, and those that survived endured a very high miscarriage rate.
Even during the much milder 1957 Asian Flu, pregnant women reportedly suffered disproportionately higher mortality rates than non-pregnant women of the same age.
The following anecdotal reports come from:
Rasmussen SA, Jamieson DJ, Bresee JS. Pandemic influenza and pregnant women. Emerg Infect Dis [serial on the Internet]. 2008 Jan [date cited].
Available from http://www.cdc.gov/EID/content/14/1/95.htm
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 (7).
Pregnant women also appear to be more susceptible to influenza than non-pregnant women, although the exact reasons for this aren't understood.
It is believed, however, that the normal protections of a woman's immune system are temporarily altered to allow her to carry what is essentially a foreign body- a fetus - without rejection.
And that alteration can place the mother (and child) at greater risk of infection during a pandemic.
Early in the outbreak of 2009 it became obvious that pregnant women were, once again, being hospitalized by the H1N1 virus at rates several times greater than for non-pregnant women.
Faced with a rising mortality rate among pregnant women, the decision was made by most public health officials to recommend antivirals, even without the benefit of better studies.
In July, a retrospective analysis of existing studies concluded that antivirals appeared safe in pregnancy, a study I covered in Canadian Medical Journal: Antivirals Safe for Pregnant And Nursing Mothers.
And by the end of July the World Health Organization was recommending the immediate use of antivirals for pregnant women infected with the virus (see WHO Recommending Immediate Antiviral Treatment For Pregnant Flu Victims).
Today, in April edition of the Journal Obstetrics & Gynecology, we get some more information that indicates that public health officials made the right call.
While limited in scope, this retrospective study showed no increase in adverse outcomes among pregnant women who received antivirals.
Obstetrics & Gynecology:
April 2010 - Volume 115 - Issue 4 - pp 711-716
doi: 10.1097/AOG.0b013e3181d44752
Original Research
Maternal and Neonatal Outcomes After Antepartum Treatment of Influenza With Antiviral Medications
Greer, Laura G. MD; Sheffield, Jeanne S. MD; Rogers, Vanessa L. MD; Roberts, Scott W. MD, MS; McIntire, Donald D. PhD; Wendel, George D. Jr MD
The entire study is a pay-per-view (follow above link for the abstract), but Medscape Today has an overview with the highlights. Follow the link to read it in its entirety.
Antepartum Antiviral Treatment of H1N1 Influenza Not Linked to Adverse Outcomes
Laurie Barclay, MD
April 8, 2010 — Antepartum antiviral treatment of H1N1 influenza is not linked to adverse maternal or neonatal outcomes, according to the results of a retrospective cohort study reported in the April issue of Obstetrics & Gynecology.
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