Prenatal diagnosis
Prenatal diagnosis (PND) is a complex of medical tests and diagnostics performed in order to reveal neural tube defects, Down syndrome, chromosome abnormalities, genetic diseases and other conditions. PND defines hereditary diseases, fetus development, general condition and sex of an embryo. 
There are different types of prenatal diagnosis. 
Non-invasive methods are absolutely safe and include ultrasound diagnostic of fetus and test for presence of biochemical markers in a blood of pregnant. 
Invasive methods presuppose medical intervention into uterus to retrieve material in order to define fetus caryotype. This is chorion biopsy, amniocentesis, placentacentesis, cordocentesis. The procedure involves retrieval of chorion cells or placenta, amniotic fluid, blood from cord. 
It is clear that prenatal methods are connected with a risk of pregnancy complications and have to be applied only in case of serious reasons. 
Medical indications for prenatal diagnosis: 
  - Pregnant women over the age of 35; 
  - Pregnant women with a high risk of child birth with chromosome abnormality; 
  - Women who have previously had premature babies or babies with a birth defect; 
  - Women who have family histories or ethnic backgrounds prone to genetic disorders, or whose partners have these diseases; 
  - Women who are pregnant with multiples (twins or more); 
  - Women who have previously had miscarriages