“Auntie, my unit just had a physical last week, everything is normal, can I not do the marriage test?” I gestured for her to do it first and said, “You are Ali, I already have your information on my computer.” I told Ali: “Although your unit has done a general health examination results are normal. But a marriage examination is different from an ordinary medical examination.” The Law of the People’s Republic of China on Maternal and Child Health, adopted by the Standing Committee of the National People’s Congress in October 1994, stipulates that premarital medical health care includes: i. Premarital medical examination ii. Premarital medical guidance iii. Premarital medical consultation Seeing that Ali was listening attentively, I was encouraged to continue: “In layman’s terms, premarital health care is centered around the possible effects of In layman’s terms, premarital health care is a series of medical examinations, counseling and guidance around diseases that may affect marriage and childbirth. It will especially incorporate family genetic disorders, such as hemophilia if the subject’s father is a hemophiliac, which will have a different impact on her having a boy or girl!” I noticed that Ari’s mouth was half-open and her eyes were wide open as she spoke. My heart sank as I pondered what I had said wrong? “Auntie doctor, what a coincidence, my father is a dozen years ago when the surgery check out hemophilia, because it is not too heavy, also did not care too much. If you say so, I happen to need a consultation.” According to the premarital medical examination process, she was first given a detailed medical examination program (including medical history inquiry, physical examination, routine auxiliary examinations and other special examinations). When all the test results are available, she is given an appointment specifically for guidance and counseling. Ali’s father has hemophilia A, a deficiency of the pro-coagulant component of factor VIII (VIII:C), which is characterized by impaired production of active thromboplastin, prolonged bleeding time, a lifelong tendency to bleed after minor trauma, and “spontaneous” bleeding in severe cases without significant trauma. Hemophilia is a sex-linked recessive disorder that is transmitted to females and develops in males. The gene that controls the synthesis of factor VIII clotting components is located on the X chromosome. When Ali heard this, she was so anxious that she hurriedly interrupted me and asked, “Will I never be able to have a healthy son? Our son is the only child of a single heir.” I reassured her that there must be a solution to the problem, so continue to listen to the science lesson we gave you. As you know, the male karyotype is 46XY and the female karyotype is 46XX. one of the X chromosomes in a daughter is from the father. There are four ways to inherit hemophilia A: 1. A hemophilia A patient married to a normal female will have a normal son and all daughters will be carriers. 2. A normal male marries a female carrier and has a son who is 50% likely to have hemophilia A and a daughter who is 50% likely to be a carrier. 3.A hemophilia A patient marries a female carrier, the probability of her daughter being a hemophilia patient and a carrier is 50% each, and the probability of her son being born with the disease is 50%. 4. People of both sexes who are hemophiliacs have children who are patients. Allie herself is a hemophilia A carrier and her lover is normal. 50% of their sons born after marriage are likely to have hemophilia A and 50% of their daughters are likely to be carriers. That is, Ali needs to be sexed during her pregnancy, and if it is a male baby, further prenatal diagnosis i.e. genetic testing for hemophilia will be required. Finally, Ali smiled and breathed a long sigh of relief. In the first year of her marriage, she gave birth to a girl. Two more years later, she became pregnant again, and at 14 weeks of pregnancy, she underwent a medically necessary sex determination for a male baby and went to a tertiary hospital in Shanghai for genetic testing for hemophilia A. The result was a healthy male. The result was a healthy baby boy. The family is lucky and we wish them the best of luck! But millions of unfortunate families are suffering. China is a country with a high incidence of birth defects, with a total incidence of birth defects of about 5.6% and up to 900,000 new cases of birth defects each year. The “three levels of prevention” measures to reduce birth defects: primary prevention includes prevention of birth defects, i.e. premarital screening, genetic counseling. Secondary prevention is to prevent the birth of defective children, mainly during pregnancy through screening and prenatal diagnosis methods, early identification of fetal congenital defects. Tertiary prevention is the early screening of newborn diseases, early diagnosis, timely treatment, avoidance or mitigation of disabilities, and ensuring the quality of life of the affected children. Premarital medical examination is of great importance to reproductive health. Premarital medical examination refers to the examination of hereditary diseases, infectious diseases and mental illnesses conducted by health care institutions for people who intend to get married. Premarital medical examination can control the birth of many children with genetic defects and improve the quality of the population; secondly, it can control the spread of infectious diseases such as sexually transmitted diseases; it can detect reproductive system diseases and promote marital happiness.