Mother-to-child transmission, also called vertical transmission, is a form of transmission from parent to offspring. Mother-to-child transmission is, as the name suggests, a process of transmission from mother to child, which is also called vertical transmission. It is a process whereby a mother can transmit possible pathogens to her offspring during the perinatal period through contact with the fetus in the placenta, in the birth canal, and during breastfeeding after pregnancy. Mother-to-child transmission can generally be categorized into four ways: 1. Transplacental transmission: Pregnant women infected with rubella, AIDS, syphilis and hepatitis B transmit the pathogens to the fetus through the placental bloodstream causing intrauterine infection. 2. Ascending transmission: streptococcus, staphylococcus, Escherichia coli, herpes simplex virus, cytomegalovirus, etc. reach the chorionic villus or the placenta from the vagina of pregnant women and cause intrauterine infection in the fetus. 3. Transmission during delivery: gonococcus, conjunctivitis inclusion bodies, herpes virus, etc. are infected in the skin, mucous membranes, respiratory tract or intestinal tract when the fetus is exposed to the severely infected birth canal during delivery. 4. Breastfeeding transmission: Hepatitis B virus and HIV can be passed to the fetus through breast milk, which is a rare form of transmission. Therefore, before starting a pregnancy, you should be sure whether you have mother-to-child transmission of pathogens, and if you do, you should be treated in time to avoid harming the health of the fetus.