The most recommended agent is N-acetyl-p-aminophenol, acetaminophen, or APAP in short. Recent scientific studies showed, that APAP does more than relieving pain and reducing fever. The compound is able to alter our immune response. Being pregnant and taking this drug bears the risk of causing alterations in the immune system of the unborn child, too. This may lead to long term consequences like increased risk for asthma and probably other auto-immune diseases in the child. With this knowledge we want to learn more about the mechanisms APAP works and especially how exactly our immune system is affected. In recent studies we showed that hormone levels were altered and that stem cell numbers in the developing child were reduced.