Child Birth of mammals

Child Birth of mammals

        During pregnancy, the uterus of a women enlarges into a huge sac having of about 4000 cc. Delivery or parturition occurs on the average at the time of the tenth missed menses that 280 days after the last menstrual period. 

        In human, at birth, the placenta and the remaining extra- embryonic membranes and lining of the uterine wall slough off and follow the new born infant down the birth canal as the after birth. As the foetus passes through the tight-fitting birth-canal, umbilical cord remains attached to the placenta, and until the moment the child takes his first breath, nourishment and oxygen are received from this source. 

        Upon exposure to the external world, stimulation coming from being chilled and from the high CO2 in his first breath. At the time of birth, the child is bluish in color but later on, he gradually becomes pink as the circulation is separated into its pulmonary and systemic parts due to the closure of foramen ovule. If the foramen ovale does fail to close, the body remains bluish in color, a condition given the term blue baby. 

        He is bluish in color because the oxygenated and reduced blood are mixed, just as they are during foetal life.