Pregnancy is an exciting time in a woman's life. Changes in your body may be matched by changes in your emotions. During pregnancy, some medications are safe and some are not. Some require a higherthan usual dose, and some doses change with the advancing pregnancy. Physicians responsible for providing care to pregnant women are aware of these different medications and their restrictions. A mother taking illegal drugs during pregnancy increases her risk for anaemia, blood and heart infections,skin infections, hepatitis, and other infectious diseases. A woman's drug use can affect both her foetusand her newborn. Most drugs cross the placenta--the organ that provides nourishment to the foetus.Some can cause direct toxic (poisonous) effects and drug dependency in the foetus. After birth, some drugs can be passed to the baby through breast-feeding. More than 90% of pregnant women take prescription or nonprescription (over-the-counter) drugs or use social drugs (such as tobacco andalcohol) or illicit drugs at some time during pregnancy. Cocaine use can lead to premature delivery of the foetus, premature detachment of the placenta, high blood pressure, and stillbirth. The criticalperiod of embryonic development, when the major organ systems develop, starts at about 17 days post-conception and is complete by 60 to 70 days. In general, drugs, unless absolutely necessary,should not be used during pregnancy because many can harm the fetus. About 2 to 3% of all birth defects result from the use of drugs other than alcohol.