Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason R.

Assertion (A): As long as the mother breast-feeds the child fully, chances of conception are almost nil up to six months following parturition.

Reason (R): If fertilisation occurs, progesterone secreted by the corpus luteum, plays a role in preventing further ovulation.

In the light of the above statements, choose the most appropriate answer from the options given below 

Assertion (A) is true. As long as the mother breast-feeds the child fully, chances of conception are almost nil. However, this method has been reported to be effective only upto a maximum period of six months following parturition.

Reason (R) is true. Progesterone, produced by the corpus luteum, suppresses the release of luteinizing hormone (LH), preventing the final maturation and release of an egg (ovulation) from the ovary. It also causes the cervical mucus to thicken, creating a barrier that makes it difficult for sperm to pass through the cervix and reach the egg. Progesterone also influences the motility of the fallopian tubes, affecting the transport of the egg and sperm and reducing the likelihood of successful fertilisation.

(R) does not explain (A). The contraceptive effect of breastfeeding is through the action of prolactin but not progesterone. Breastfeeding stimulates the release of the hormone prolactin. Prolactin plays a crucial role in promoting lactation and has the additional effect of suppressing the secretion of gonadotropin-releasing hormone (GnRH). GnRH is responsible for triggering the release of luteinising hormone (LH) and follicle-stimulating hormone (FSH), which are essential for ovulation. The suppression of GnRH, in turn, suppresses ovulation, reducing the likelihood of conception.