WASHINGTON, D.C. ? The abortion pill RU-486 was cleared as the reason for at least one woman’s death by federal health officials on Monday. A second woman’s death remains under investigation.

The Food and Drug Administration said the one death was unrelated to either abortion or use of the pill. The second woman showed symptoms of infection. Four other women have died of a rare but deadly infection after undergoing pill-triggered abortions.

In those four deaths, all involving Californians, the women tested positive for Clostridium sordellii. The FDA has warned doctors to watch for infection by the bacterium. However, the drug, also called Mifeprex or mifepristone, has not been proved to be the cause in any of those cases, the FDA has said.

The recent deaths sparked renewed calls to ban the abortion pill.