For the majority of hereditary diseases typical family affair distribution, ie, the repetition of the same disease among relatives over several generations.

In marriages between distant relatives, or among people living in areas where small migration of people, probability of birth of children with developmental disabilities is much higher. Currently, some hereditary diseases, if they are timely found (especially in the first days and weeks of life) have been successfully treated.

Major role in the pathology of the fetus and newborn belongs immunological incompatibility of blood between mother and fetus in Rh-factor, or blood group. When Rh-negative blood of pregnant women and Rh-positive blood, obtained fruit from his father, due to hit in the maternal blood in fetal erythrocytes a woman's body produced anti - rhesus antibodies. They penetrate through the placenta into the fetal blood and, being directed against the erythrocytes cause their destruction and anemia. The fetus is developing hemolytic disease.

This disease of the fruit may develop even in those cases where woman with Rh negative blood may flow was Rh-positive donated blood before pregnancy. Women with Rh negative blood should refrain from production of induced abortion, as during the operation rhesus positive fetal red blood cells can penetrate into the blood of mother and induce the formation of antibodies, disastrous for the fetus with subsequent - maintaining pregnancy. Among the many environmental factors that could cause disruptions in development of the fetus, neposlednee place belongs to the medicines.

Currently, about 80% of women during pregnancy are different medicines, including those active, as hormonal funds, antibiotics, tranquilizers, etc. In some countries, conducting special studies to identify teratogenic, iecausing deformity, properties of drugs, so Most of the recommended drugs for pregnant harmless to the fetus. Moreover, the drugs have a positive impact on development of the fetus with severe illness of the mother.