The CDC recommends pregnant women suspected with H1N1 obtain treatment within 48hrs of the onset of symptoms. Symptoms manifest as an “acute respiratory influenza-like illness (e.g., cough, sore throat, rhinorrhea) and fever.” http://www.cdc.gov/h1n1flu/clinician_pregnant.htm

Pregnant women are at high-risk for life-threatening infections including pneumonia as well as pregnancy complications. The CDC advises that while testing for H1N1 in pregnant women with symptoms is ideal, if testing and test results are not available within the first 2 days of onset of symptoms, the mother and child may be at risk if treatment is not provided due to the potential rapid progression of the illness as seen in other cases. 

The bottom line says the CDC, “The highest priority message is to treat pregnant women with influenza-like illness as soon as possible; treatment should not be withheld pending results of testing for influenza, if testing is done.”

For the full advisory from the CDC, Pregnant Women and Novel Influenza A (H1N1)
Virus: Considerations for Clinicians visit http://www.cdc.gov/h1n1flu/clinician_pregnant.htm