Preconception genetic testing is done by drawing blood. Pre-pregnancy genetic testing is mainly a test of human chromosomes, which can be done by drawing blood, mainly by extracting DNA fragments from cells and checking for chromosomal abnormalities. This test can screen out some recessive genetic diseases of chromosomes. If both spouses or one of them have some autosomal recessive genetic diseases, the doctor will judge the risk of developing the disease according to the specific conditions of the people who are preparing for pregnancy, and if necessary, can avoid the birth of children with genetic diseases through some interventions, such as carrying out the 3rd generation of in vitro fertilization and so on. Pre-conception genetic testing for eugenics has a very important significance, it is recommended that pregnant couples actively cooperate with the doctor to carry out the examination, pre-pregnancy testing in addition to genetic testing, but also to do some other aspects of the examination, it is best to get pregnant under the state of health.