Read the given passage and answer the following questions :
The average duration of human pregnancy is about 9 months which is called the gestation period. Vigorous contraction of the uterus at the end of pregnancy causes expulsion/delivery of the foetus. This process of delivery of the foetus (childbirth) is called parturition. Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex. This triggers release of oxytocin from the maternal pituitary. Oxytocin acts on the uterine muscle and causes stronger uterine contractions, which in turn stimulates further secretion of oxytocin. The stimulatory reflex between the uterine contraction and oxytocin secretion continues resulting in stronger and stronger contractions. This leads to expulsion of the baby out of the uterus through the birth canal – parturition. Soon after the infant is delivered, the placenta is also expelled out of the uterus. The mammary glands of the female undergo differentiation during pregnancy and starts producing milk towards the end of pregnancy by the process called lactation. This helps the mother in feeding the new- born. The milk produced during the initial few days of lactation is called colostrum which contains several antibodies absolutely essential to develop resistance for the new-born babies. Breast-feeding during the initial period of infant growth is recommended by doctors for bringing up a healthy baby.
Given below are two statements:
Statement I: hCG, hPL and relaxin are produced in women only during pregnancy.
Statement II: During pregnancy, the levels of hormones like estrogens, progestogens, cortisol, prolactin and thyroxine are decreased several-folds in the maternal blood.
In the light of the above statements, choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Statement I is correct but Statement II is incorrect.
During pregnancy the placenta also works as an endocrine tissue, and the hormone pattern of the mother changes. Some hormones appear only in pregnancy, while the levels of several others go up.
Statement I: hCG, hPL and relaxin are produced in women only during pregnancy. — True. hCG (human chorionic gonadotropin) and hPL (human placental lactogen) are made by the placenta, and relaxin is secreted by the ovary in the later phase of pregnancy. None of them is made outside pregnancy.
Statement II: During pregnancy, the levels of hormones like estrogens, progestogens, cortisol, prolactin and thyroxine are decreased several-folds in the maternal blood. — False. The levels of these hormones are increased several-folds, not decreased. The rise is needed for the growth of the foetus, the metabolic changes in the mother and the maintenance of pregnancy.
NCERT Extract:
Pregnancy and Embryonic Development – “… Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens, etc. In the later phase of pregnancy, a hormone called relaxin is also secreted by the ovary. Let us remember that hCG, hPL and relaxin are produced in women only during pregnancy. In addition, during pregnancy the levels of other hormones like estrogens, progestogens, cortisol, prolactin, thyroxine, etc., are increased several-folds in the maternal blood. Increased production of these hormones is essential for supporting the fetal growth, metabolic changes in the mother and maintenance of pregnancy.”