The process of giving birth to the young one is known as parturition .
A developing foetus secretes hormones from its adrenal glands . These hormones diffuse into the maternal blood and accumulate to stimulate the release of oxytocin from the mother's posterior pituitary gland .
Oxytocin causes the forceful contraction of smooth muscles of myometrium called labour pains .The foetal membranes burst and amniotic fluid is released but foetal membrane remain behind .This labour pain pushes the young gradually out through the dilated cervix and vagina with the head foremost .
It is aided by a reflex and voluntary contraction of abdominal muscles .
In the beginning the labour pain occurs once every half or quarter of an hour but soon becomes more frequent .
It is followed by the expulsion of the umbical cord placenta and foetal membranes after birth .
Sometimes the foetus fails to come out then the body is delivered by surgical procedure .Such a baby' called caesarean .
Relaxin - It causes widening of pelvis by relaxing the public symphysis of the pelvicgirdle.
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