The government is warning doctors who perform in vitro fertilization that a drug combination given to some patients may have been a factor in a pregnant woman's death.

The 38-year-old woman who died from brain hemorrhaging in 1996 was taking aspirin and heparin in hopes of boosting her chances of a successful pregnancy, the Centers for Disease Control and Prevention in Atlanta reported Thursday.Though the drug combination increases chances of bleeding, the CDC did not conclude that it caused her death.