先天异常系对出生时存在的形态或功能异常而言,从广义上讲胎生期死亡和发育迟缓也包括在内。先天异常的成因有三:(1)遗传起决定性作用;(2)环境起决定性作用;(3)遗传与环境共同影响。Brent指出人类先天异常的成因以(3)为主。先天异常多数在器官形成期即受精后第三至八周(临床上由末次月经第一天算起满4～9周)遭受侵害时而发生的,在这以前(受精后2周左右)遭侵害时多数发生胎儿死亡,如免于死亡则可继续发育。生殖生理学是研究从生殖细胞形成、受精、着床到胎盘形成这段过程中母体方面的 Congenital anomalies at birth, the existence of morphological or functional abnormalities, in a broad sense, the epigenetic death and stunting are also included. There are three causes of congenital anomalies: (1) genetic play a decisive role; (2) the environment plays a decisive role; (3) genetic and environmental common impact. Brent pointed out that the cause of human antecedent abnormalities mainly (3). Most of the congenital anomalies occur during the third to eighth weeks after organogenesis (ie, from the first day of the last menstrual period on the first day of the menstrual cycle) to infringement, and were infringed before (about 2 weeks after fertilization) When the majority of fetal deaths, such as death from death can continue to develop. Reproductive physiology is to study from the germ cell formation, fertilization, implantation of the placenta formation in the process of maternal aspects