The CDC has announced that almost half of all pregnant women were vaccinated with the H1N1 or combined influenza vaccination during the "influenza" season of 2009/2010. Women who were told by their physicians to get the flu shot were three times more likely to get it, and women who were specifically told to get the H1N1 vaccination were a staggering 10 times more likely to accept the vaccination.
However, data presented to CDC's Advisory Committee on Children's Vaccines shows the rate of miscarriage attributed to vaccination during the same period rose by 700% compared to both 2007 and 2008 (view complete resources here). The report was presented to the CDC's Advisory Committee on Children's Vaccines by the National Coalition of Organized Women, who corroborated the miscarriage and stillborn rates reported on the CDC's VAERS (Vaccine Adverse Event Reporting System) database with an independent review of miscarriages associated with the influenza and H1N1 vaccination during the winter of 2009-2010.
VAERS showed that in the two years preceding the CDC's recommendation for all pregnant women to be vaccinated against influenza and H1N1, 7 miscarriages per year were reported as attributable to vaccination. In 2009, that number rose to 178. Health statisticians who use reporting methods like VAERS have shown that between 10-90% of cases are missed due to under-reporting, so they typically corroborate the information with another source and use a formula that gives a best-estimate of the actual numbers involved. By using this formula, NCOWs estimated that 1588 miscarriages (within a range of 946 to 3587) in 2009 were associated with pregnant mothers who were vaccinated with the H1N1 or combined influenza shot.
Eileen Dannemann, Director of NCOW, has presented the information to the CDC three times. The CDC's response? Despite being presented with the information from her own database three times, Dr. Marie McCormick, chair of the Vaccine Risk and Assessment Working Group, has reported publicly that "there were absolutely no H1N1 vaccine-related adverse events in pregnant women in 2009/10." (see link)
It's not like they haven't had the opportunity to figure it out- In their above survey on vaccination compliance, the CDC researchers didn't bother to ask any of the pregnant women if they contracted the flu while pregnant (the CDC stopped confirming actual H1N1 cases in July 2009) and didn't ask about any complications associated with the shot. In fact, the CDC has not reported on miscarriages or stillbirths in the US since 2008. They will release their own analysis through their Pregnancy Risk Assessment Monitoring System (PRAMS) when the next 3 year data gathering cycle completes in 2011.
CDC (2010). "Seasonal Influenza and 2009 H1N1 Influenza Vaccination Coverage Among Pregnant Women --- 10 States, 2009--10 Influenza Season." Morbidity and Mortality Weekly Report December 3, 2010 / 59(47);1541-1545.
Dannemann E., King PG, and Goldman GS (2010). "Exhibit 4 –November 2, 2010. A Comparison:
Probable 2009-A-H1N1-Flu-shot-related Fetal Losses and Maternal Deaths in Pregnant Women Attributed to Unverified H1N1-infection-related Complications; an Upside-down Risk-Benefit Reality."