An estimated 40% of Americans will be infected with the H1N1 virus this season.  Seasonal influenza causes about 20,000 deaths annually in the U.S.
 
Pregnant women appear to be at increased risk for complications from the H1N1 influenza because:

1. there is an alteration of normal immune status in pregnancy
2. pregnancy has effects on normal respiratory function due to pressure on the lungs
3. of possible hormonal effects.

There have been six recently reported deaths among pregnant women.  
The Centers for Disease Control and Protection (CDC) has issued an advisory for immunization efforts to be directed at five key or high risk populations in the U.S.:

 All pregnant women
 People who live with or care for children younger than 6 months of age
 Health care and emergency services personnel
 Persons between the ages of 6 months through 24 years of age
 People from ages 25-64 years who are at higher risk for novel H1N1 because of chronic health disorders or compromised immune systems

The Kentucky State Department of Public Health has issued an alert encouraging all pregnant women with an acute, febrile respiratory illness to be cultured with special medium (M4RT) for H1N1 virus. Women’s Care Center will be prepared for this situation.

The vaccine may be given in combination with the seasonal influenza vaccine. It is, however, recommended that two injections be given, likely 2 - 4 weeks apart.  The dose is 15 micrograms of antigen per vaccination.  Seasonal influenza is recommended to be given earlier than usual this year, probably in September or October. If all of the five at-risk categories are immunized, it will require 159 million doses for one shot each and 318 million for two shots each.

It is now estimated that there will be about 45 million doses available in early October with more to follow.  It will be distributed to health departments with distribution controlled by them at state and local levels.  

It will be important for all obstetricians to encourage their pregnant patients and ultimately the household contacts of their newborn infants to be immunized.  

It is of note that persons born before 1957 appear to be at a lower risk of infection than younger persons because of immunity acquired from an outbreak of swine flu at that time.