Parturition and Lactation | NEET Biology

PARTURITION

Parturition is the act of expelling the full - term young one from the mother's uterus at the end of gestation .

Gestation ( pregnancy ) is completed in about 266 days from conception .

Process of parturition is induced by both nervous system and hormones secreted by the endocrine glands of the mother .

The signals for childbirth ( parturition ) originate from the fully matured fetus and placenta which induce mild uterine contractions called fetal ejection reflex

This causes quick release of oxytocin which promotes contraction of uterine muscles from the maternal posterior lobe of pituitary gland . The amount of oxytocin is increased just before and during " labour pains “ ( pains of childbirth )

Relaxin secreted by the placenta increases the flexibility of the pubic symphysis and ligaments of the sacroiliac and sacrococcygeal joints and helps to dilate the uterine cervix during labour pains .

The hormone most recently found to be produced by the placenta is corticotropin - releasing hormone ( CRH ) , which in non - pregnant women is secreted only by neurosecretory cells in the hypothalamus .

LACTATION

The mammary glands of the female undergo differentiation during pregnancy and start producing milk towards the end of pregnancy by the process called lactation .

Secretion of milk is influenced by prolactin , secreted by anterior lobe of the pituitary gland and ejection of milk is stimulated by oxytocin , secreted by posterior lobe of the pituitary gland . This helps the mother in feeding the new born .

The first milk which comes from the mammary glands of mother produced during initial 2 or 3 days after childbirth is called colostrum . Colostrum contains antibodies ( IgA ) that provide natural passive immunity to the new born infant .

Manish Mevada

M.Sc, M.Phil, B.Ed