Question

Which of the following processes are directly affected by hormonal contraceptives?

I. Fertilisation
II. Implantation
III. Ovulation
IV. Capacitation

• A. I and II only
• B. I, II and IV
• C. II, III and IV
• D. I and III only

Answer 1

The correct option is C II, III and IV

Hormonal contraceptives are a kind of chemical contraceptives. Chemical contraceptives use chemical constituents to prevent pregnancy. When the chemicals used are steroid hormones, they are known as hormonal contraceptives. Hormonal contraceptives aim at preventing a number of processes that could lead to fertilisation and subsequently implantation. The hormonal contraceptives contain small doses of progesterone alone, or progesterone-estrogen combinations which are given to women. Progestogen is equivalent to progesterone and is a natural or synthetic steroid hormone. Progestin is a synthetic progestogen.
Progestin suppresses the release of GnRH from the hypothalamus. As a result, there is no release of LH and FSH from the anterior pituitary. There is no FSH or LH peak obtained during the menstrual cycle. This prevents ovulation (the release of secondary oocyte from the mature follicle). In the absence of FSH, there is no growth and development of ovarian follicles, so no estrogen is released. The estrogen component of the contraceptives compensates for this absence of estrogen and maintains the normal thickening of the uterus. The uterus cells don’t proliferate because of low levels of estrogen and hence are not prepared for implantation. If by chance, there is fertilisation somehow, the embryo won’t be implanted in the endometrium.
Progestin also inhibits the capacitation of sperms. Capacitation of sperms is required for them to be able to penetrate through the layers of the secondary oocyte to bring about successful fertilisation.
As we can see, fertilisation is not directly affected by hormonal contraceptives. The processes that might lead to successful fertilisation are affected. Fertilisation occurs in some cases. In case successful fertilisation occurs by bypassing all the steps, implantation is inhibited. Thus pregnancy is avoided altogether.