The principle of emergency contraceptive pills, it is important to understand this knowledge

The contraceptive principles of various contraceptives are different. For example, some contraceptives achieve the contraceptive effect by inhibiting ovarian ovulation, some contraceptives prevent the combination of egg and sperm, and some contraceptives achieve the purpose of contraception by changing the normal peristalsis of the fallopian tubes.

1. Inhibit ovarian ovulation. After a woman reaches sexual maturity, she releases an egg from her ovary every month. This is done under the interaction and control of the hypothalamus, pituitary gland and ovary. The hypothalamus secretes a substance called gonadotropin-releasing hormone, which acts on the pituitary gland, causing it to secrete a substance called gonadotropin. Under its action, the follicles in the ovaries develop and mature, release eggs, and secrete estrogen and progesterone. The estrogen and progesterone produced by the ovaries in turn act on the pituitary gland in the hypothalamus, affecting their secretory functions. When the ovaries secrete more estrogen and progesterone, they inhibit or reduce the secretion of gonadotropin by the pituitary gland through the hypothalamus. When gonadotropin is suppressed or reduced, the follicles in the ovaries will not mature and ovulate. Because oral contraceptives and contraceptive injections contain estrogen and progesterone, these two hormones in the human body increase, inhibiting the secretion of gonadotropin-releasing hormone in the hypothalamus. Therefore, the secretion of gonadotropin by the pituitary gland is also inhibited, thereby inhibiting the development, maturation and ovulation of follicles, thus achieving a contraceptive effect. After stopping the medication, the ovaries quickly resume ovulating.

2. Change the morphology of the endometrium. The endometrium also changes shape cyclically during the menstrual cycle. When it is affected by estrogen and progesterone, the glands of the endometrium proliferate, the spiral arteries grow, and the entire endometrial layer thickens and becomes rich in nutrients, making it easier for the fertilized egg to implant. However, after taking birth control pills or getting birth control injections, the endometrium is relatively thin, has fewer glands, and has poor secretion. This underdeveloped endometrium cannot accept the fertilized egg to implant, so pregnancy will not occur.

3. Change the properties of cervical mucus. The mucus in your cervix also changes with your menstrual cycle. When menstruation just starts, there is not much estrogen in the body and the amount of cervical mucus is also small. When ovulation is approaching, the estrogen level in the body increases, and more mucus is produced, which is thin and transparent, facilitating the passage of sperm and protecting its vitality. After ovulation, under the influence of progesterone secreted by the ovaries, the mucus secreted by the cervix becomes viscous and opaque, which is not conducive to the passage of sperm. The progestin in oral contraceptives or contraceptive injections can make the mucus secreted by the cervical glands thicker, which is not conducive to the passage of sperm and can play a contraceptive role.

4. Change the normal peristalsis of the fallopian tube. The estrogen in oral contraceptives and contraceptive injections can accelerate the movement of the fallopian tube, and the progesterone has a certain effect on the cilia and secretory cells of the fallopian tube epithelium, which speeds up the movement of the fertilized egg in the fallopian tube. When the fertilized egg reaches the uterus, the endometrium is still immature, which is not conducive to the implantation of the fertilized egg.