Knowledge about safety and efficacy of drugs prescribed during pregnancy and lactation is important for every clinician. Due to the fact that approximately 50% of pregnancies are unplanned, there is concern about possible adverse drug reactions (ADR) of drugs taken during the early and most vulnerable stage of pregnancy. Furthermore, many women with chronic illnesses that require treatment are planning to become pregnant. Although there is limited number of drugs that are contraindicated during pregnancy due to their teratogenic or other ADR, there is much fear about prescribing drugs to pregnant women. This raises as much concern about under prescribing drugs as overprescribing them. Inadequate recommendations on drug use during pregnancy may lead to unnecessary therapy cessation or inadequate therapy of chronic or acute illnesses leading to increased risk for adverse pregnancy outcomes. When consulting on pharmacotherapy during pregnancy, physicians should take the following approach: 1. Determine if drug therapy is necessary; 2. Choose the safest drug available; 3. Monitoring drug therapy (e.g. measurement of plasma drug concentration, ADR); 4. Advice on drug use (e.g. avoiding specific drug-drug combinations); 5. Seek advice from clinical pharmacologist. This article provides a review of rational pharmacotherapy for the most common clinical conditions during pregnancy.