Injectable contraceptives inhibit ovulation by–

Correct option is D

Sol. Injectable contraceptives like Depo-Provera (DMPA) work through multiple mechanisms. They primarily suppress ovulation by preventing the LH surge and reducing FSH levels, which halts follicular development. They also thicken cervical mucus, making it hard for sperm to reach the egg, and alter the endometrium, reducing the chances of implantation. Additionally, they may slow down the movement of the ovum through the fallopian tubes, enhancing contraceptive efficacy.
Explanation of each option:
· (a) Preventing the LH surge and lowering FSH and LH – This is the primary mechanism. LH and FSH are essential for follicle maturation and ovulation. Suppressing these hormones prevents the release of an ovum, stopping pregnancy from occurring at the first step.
· (b) Thickening the cervical mucous and rendering the endometrium less suitable – This is the secondary mechanism. The thick mucus acts as a barrier to sperm, and the thin endometrium is unsuitable for implantation, even if fertilization occurs.
· (c) Hindering the rate of ovum transport – Slowing ovum transport means that the timing between ovulation and fertilization is disturbed, lowering the chance of successful conception. Although not the main mechanism, it contributes to efficacy.
· (d) All of these – Correct. Injectable contraceptives act via all three mechanisms, making them highly effective and long-acting methods for birth control.