42.

How can the scientific understanding of the mentrual cycle of human females help as a contraceptive measure ?

Scientific understanding of menstrual cycle of human females is very important as a contraceptive measures.

It helps in the following ways :

(i) Safe period (Rhythm method) A week before and a week after menstrual bleeding is considered as the safe period for sexual intercourse. The idea is based on the following facts :

(A) Ovulation occurs on 14th day of cycle and ovum survives for about 2 days.
(B) Sperms remain alive for about 3 days. This method reduces the chances of pregenancy by about 80%.

(ii) Pills used by females are also dependent on the menstrual cycle. The pills have to be taken daily for a period of 21 days starting preferably within the first five days of the menstrual cycle. It is repeated again after a period of 7 days. These inhibit ovulation and implantation as well as alter the quality of cervical mucus to prevent/retard entry of sperms.