About 50 °/c, of pregnancies are not planned and this information is very important when prescribing drugs to women in the generative phase. Studies on the use of medications in pregnancy have shown that as many of 80-99 % of pregnant women rake four to seven drugs during pregnancy. According to other studies, between 40 and 90 % of pregnant women rake one or more drugs during pregnancy. Most drugs can pass through the placenta and have potential pharmacological and teratogenic effects on the embryo and fetus. Unfortunately, also some untreated diseases can affect both mother and fetus. Therefore, a rational approach to drug development for pregnant women should incorporate assessment of the risks of untreated maternal illnesses and how an untreated disease may influence the health of the unborn child. When selecting therapy, two individual patients should be taken into account, the mother and the unborn child, and the decision should be based on the assessment of risks and benefits for both. Adverse effects of drugs on the pregnant woman and the child are tested on animals. The resulting data are still insufficient to ensure adequate assessment of the hazards in human pregnancy. For a more complete picture, use is made of the data obtained from various global databases of drug side effects and literature data about pregnant women unaware that they are pregnant taking a medication despite the risk of harming the fetus. Drug metabolism and pharmacokinetics are much more complicated in pregnancy because of the impact of altered physiological parameters in the mother that may affect ADME.