Human Reproduction – Parturition and Lactation: NEET MCQs with Answers

Explanation: Prolactin is concerned with milk production after delivery. Parturition is initiated by prostaglandins, oxytocin and a rise in the oestrogen to progesterone ratio.

Explanation: The signals for parturition originate from the fully developed foetus and the placenta, which together induce mild uterine contractions called the foetal ejection reflex. This triggers oxytocin release from the maternal pituitary, which strengthens the contractions in a positive feedback loop until the baby is expelled.

Explanation: Colostrum is rich in immunoglobulin-A (IgA), also called secretory immunoglobulin. Transfer of these ready-made antibodies to the newborn provides natural passive immunity during its first days of life.

Explanation: Oxytocin, a peptide hormone produced in the hypothalamus and released by the posterior pituitary, causes contraction of the uterine smooth muscle in the foetal ejection reflex and contraction of the myoepithelial cells of the mammary glands in the milk ejection reflex.

Explanation: Prolactin is not involved in the initiation of parturition; it is released after childbirth to stimulate milk secretion from the mammary glands. Parturition is initiated by a rise in the oestrogen–progesterone ratio, synthesis of prostaglandins and release of oxytocin from the maternal pituitary.

Explanation: The reflex is set off by signals from the mature foetus and placenta, which stimulate mild contractions of the uterus. These in turn provoke the release of oxytocin, which strengthens the contractions and so provokes further oxytocin release — a positive feedback that culminates in delivery.

Explanation: Both true. Colostrum's antibodies (IgA) explain why early breastfeeding is essential — passive immunity.

Explanation: Colostrum is the early milk rich in IgA antibodies. Signals from the fully developed foetus and placenta produce mild contractions called the foetal ejection reflex. Human pregnancy lasts about nine months, and parturition is the expulsion of the baby through the birth canal.

Explanation: The roles are reversed in the incorrect statement: prolactin stimulates the synthesis of milk, while oxytocin causes milk ejection. The other statements are true, since colostrum is the early milk, the glands differentiate during pregnancy, and breast feeding is advised for healthy infant growth.

Explanation: The mammary glands differentiate during pregnancy under the combined action of estrogen, progesterone and prolactin, whose levels rise in the maternal blood. Oxytocin acts later to eject milk, while FSH and LH regulate the ovarian cycle.

Explanation: Alveolar cells secrete milk, which finally leaves through the lactiferous duct. Prolactin from the anterior pituitary stimulates milk synthesis. Oxytocin from the posterior pituitary causes ejection of milk when the baby suckles.

Explanation: Signals from the fully developed foetus and placenta first induce mild uterine contractions, called the foetal ejection reflex. This triggers the release of oxytocin from the maternal pituitary, and oxytocin causes stronger contractions that stimulate still more oxytocin secretion. The increasingly strong contractions expel the baby through the birth canal. The placenta is expelled from the uterus soon after the infant is delivered.