Pandemic Flu May Contribute Significantly to Pregnancy-Related Death Rate
Pandemic influenza may "notably increase" the overall death rate for pregnant American women in 2009. The prediction is based on data from pregnant or postpartum women who died of infection with the 2009 H1N1 virus in California during a 4-month period. An assessment of flu-related hospitalizations and deaths in this population is available in the latest issue of the NEJM.
Investigators from the California Pandemic (H1N1) Working Group collected data from 239 pregnant, postpartum, or nonpregnant women of reproductive age who were hospitalized with or died of probable or confirmed* pandemic flu between April 23 and August 11, 2009. Most (~78%) acquired infection in June or July.
Underlying chronic conditions, specifically asthma, were observed in substantial percentages of all women and particularly nonpregnant women—confirming that pregnancy itself is a risk factor for severe infection with the 2009 H1N1 virus.
|
Patient Feature |
Pregnant |
Postpartum |
Not Pregnant |
P Value [b] |
|
Chronic illness, % |
34 |
25 |
60 |
<.001 |
|
Asthma, % |
16 |
0 |
28 |
.04 |
|
Nongestational diabetes, % |
2 |
0 |
15 |
.002 |
|
Immunosuppression, % [c] |
3 |
0 |
15 |
.006 |
|
Neurologic disorder, % |
1 |
12 |
10 |
.009 |
|
Hypertension, % |
5 |
12 |
17 |
.009 |
|
Gastrointestinal disease, % |
2 |
0 |
14 |
.006 |
a. Percentages based on pregnant women for whom data were available.
b. Pregnant women vs nonpregnant women.
c. Related to cancer or transplantation.
Notable among pregnant women was a rapid clinical deterioration that looked qualitatively different from typical seasonal influenza. About 25% of pregnant women who required mechanical ventilation were intubated at the time of hospitalization, and several deliveries were made in intensive care units. ICU admission and death were about 4 times more likely in pregnant women who received antiviral treatment after 48 hours of symptom onset. Delay of antiviral treatment appeared to be associated with false-negative rapid-antigen test results.
During the 4-month period, the mortality ratio for pandemic flu in pregnant women was estimated at 4.3. Previous mortality ratios for all-cause death among pregnant women in California (2005) and in the United States (2006) were 19.3 and 13.3, respectively.
The authors urge pregnant women to be vaccinated against pandemic flu on the basis of their findings and preliminary vaccine-trial results.
RT-PCT = reverse-transcriptase polymerase chain reaction.
* Probable disease was defined as a positive result by real-time RT-PCR for influenza A that could not be subtyped H1 or H3. Confirmed disease was defined as a positive result by real-time RT-PCR that was specific of 2009 H1N1 influenza.
Depiction of H1N1 virus from Wikipedia.
