胎儿在母亲子宫内。生存和生长发育所需要的氧和营养物质完全依赣母亲的供给,胎儿各脏器的生理状况也适应于依赖母亲。到正常足月出生时.随着脐带的结扎,标志着胎儿期的结束和新生儿期的开始。这种变化,不仅是生活环境发生重大变化,更重要的是新生儿重要脏器功能和生理状况发生重大变化,以适应在外界环境的独立生存。正常情况下,这种变化是有序发生的,是生理性的,胎儿能够安全适应这种变化。从而顺利过渡到新生儿。 Fetus in the mother’s womb. Oxygen and nutrients required for survival and growth are entirely dependent on the supply of the mother, and the physiology of the various organs of the fetus is also adapted to depend on the mother. By the time of normal full-term birth, the ligation of the umbilical cord marks the end of the fetal period and the beginning of the neonatal period. This change is not only a major change in the living environment, more importantly, important changes in the function and physiological status of important organs of the newborn to adapt to the independent survival in the external environment. Under normal circumstances, this change occurs orderly, is physiological, the fetus can safely adapt to this change. So that a smooth transition to newborns.