Q. 275.0( 3 Votes )
Gestation period refers to the average duration of human pregnancy, i.e. about 9 months. Vigorous contractions at the end of pregnancy cause the ejection or delivery of the foetus and are called parturition (child birth). Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition arise from a fully developed foetus and placenta which induce mild uterine contractions called foetal ejection reflex. This triggers the release of oxytocin from maternal pituitary. Oxytocin acts on uterine muscles and causes stronger uterine contractions which stimulate further secretion of oxytocin. The stimulatory reflex between uterine contractions and oxytocin secretion continues resulting in stronger contractions and finally leads to expulsion of the baby out of the uterus through the birth canal – parturition.
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