第七版妇产科--第十一章妊娠时限异常（The seventh edition of Obstetrics and Gynecology, the eleventh chapter abnormal pregnancy time）.doc

第七版妇产科--第十一章妊娠时限异常（The seventh edition of Obstetrics and Gynecology, the eleventh chapter abnormal pregnancy time） The first day of abortion 28 weeks of gestation, fetal weight is less than 1000g and the terminator called abortion (abortion). Abortion occurred in 12 weeks of pregnancy who say early abortion, pregnancy occurred in 12 weeks less than 28 weeks that late abortion. Abortion is divided into spontaneous abortion and artificial abortion, the contents of this section is limited to natural abortion. About the incidence of spontaneous abortion was accounted for 15%. The majority of early pregnancy abortion. There are many reasons why l [causes of abortion, mainly in the following aspects. 1. genetic defects in early spontaneous abortion, fetal chromosomal abnormalities accounted for 50% to 60%, was followed by an abnormal number of chromosomes, chromosome structural abnormalities. Three, X monomer and triploid chromosome number abnormality; fracture, inversion, deletion and translocation of abnormal structure. The majority of embryonic chromosomal abnormalities for ending abortion, pull the minority may continue to develop into a fetus, but also have certain function abnormality or malformation after birth. If abortion, pregnancy outcome and sometimes only a empty gestational sac or degenerated embryos. Many of the 2. environmental factors influence the reproductive function of adverse external factors, directly or indirectly to the embryo or fetus damage. Too much exposure to certain harmful chemical substances (such as arsenic, lead, benzene, formaldehyde, chloroprene, ethylene oxide etc.) and physical factors (such as radiation, noise and high temperature, etc.) can cause abortion. 3. maternal factors (1) systemic disease: suffering from acute disease of pregnancy, high fever can cause uterine contraction caused by abortion; bacterial toxin or virus (herpes simplex virus, cytomegalovirus) into the fetal blood circulation through the placenta, fetal death an