Chinanews, Beijing, Sept 19 – The Peking University Reproductive Health Research Institute recently listed the five major reasons that will easily lead mothers to give birth to babies with prenatal birth defects.The five major reasons are: women who get pregnant when she is already 35 years old or even older; women who are infected by virus cells, especially the Rubella virus, during her early days of pregnancy; women who encounter trace element deficiency, especially iodine or folic acid deficiency during her early days of pregnancy; pregnant women who are exposed to X rays or other harmful chemical elements during her early days of pregnancy; women who take pills without consulting doctors in her early days of pregnancy.The Peking University Reproductive Health Research Institute has reached the conclusion after carrying out a survey of 20 million babies and children. Some of the babies covered by the investigation are not yet born while some are already seven years old. The investigation lasted for more than ten years.For pregnant women who might encounter one or several of the above situations, the doctor in charge of the research program suggests that they should take the type-B ultrasonic medical checks in their early days of pregnancy. The ultra sound monitoring can identify most of the cases related with fetal congenital heart disease, abnormalities of nerve cords, cleft lip, etc. Related research shows if expectant mothers take enough folic acid supplements during their early days of pregnancy, they can avoid the abnormality of nerve cords, and also avoid 35% of fetal congenital heart disease and 15% of other abnormalities of the babies.