Q.

Which of these is not an important component of initiation of parturition in humans              [2015]

1 Release of oxytocin  
2 Release of prolactin  
3 Increase in estrogen and progesterone ratio  
4 Synthesis of prostaglandins  

Ans.

(2)

Process of parturition is induced by both nervous system and hormones secreted by the endocrine glands of the mother. The signals for child birth (parturition) originate from the fully developed fetus and placenta which induce mild uterine contractions called fetal ejection reflex. This causes quick release of oxytocin from the maternal posterior lobe of pituitary gland which induces labour pains. Prostaglandins, progesterone and estrogen also play a role. Prolactin is the hormone which induces lactation and has no role in parturition.