Is it useful to take short-acting contraceptive pills after sex?

Regardless of the use, emergency contraception is generally taken for a few days beforehand, and only birth control pills, such as Yuting and Jin Yuting, are taken afterwards. After that, as long as you take birth control pills within 72 hours, they will be effective. The sooner you use them, the better the effect will be. In most cases, the success rate can reach 90%.

The main functions of emergency contraception: inhibit ovulation, change the cervical mucus, make it difficult for sperm to penetrate, or reduce the production of glycogen in the uterine glands to make it difficult for the embryo to survive, or change the movement of the uterus and fallopian tubes to block the transport of sperm and egg.

The mechanism of action is multi-stage and multifaceted, and varies depending on the ingredients, Chinese herbal preparations, dosage and method of use. For example, combined preparations of estrogen and estrogens are mainly used to inhibit ovulation, low-dose estrogens are mainly used to block fertilization, and large doses of estrogens are mainly used to prevent embryo implantation. The classification of the above application principles is relative.

1. Steroidal estrogens that inhibit ovulation

After oral administration, the blood concentration of estrogen and estrogens increases, which inhibits the secretion of growth hormone released by the hypothalamus-pituitary gonadotropin through a negative feedback effect; in addition, the estrogen in the blood also has a direct inhibitory effect on the anterior pituitary gland, which can reduce the secretion of gonadotropin in the anterior pituitary gland, and the levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the blood are reduced. Because FSH secretion is inhibited, the growth and maturity of the egg is hindered, there are no perfect eggs available for ovulation, and the estrogen peak before ovulation is also eliminated. Because the LH surge in the middle and late stages of the menstrual period disappears, the ovulation process is suppressed.

2. Steroidal estrogens that block fertilization

After oral administration of high doses of estrogen, the physical and chemical properties of cervical mucus are changed, preventing fertilization. Estrogen can inhibit the secretion of cervical mucus, making the amount of mucus less but the viscosity higher, the cellular component increased, which is not conducive to the penetration of sperm, making it difficult for sperm to pass through, and achieving the effect of blocking fertilization. When estrogen is dominant, sperm capacitation is inhibited and the fertilization ability is lost, thus affecting fertilization. Continuous use of estrogen throughout the menstrual cycle can prevent fertilization. Its advantage is that it does not contain estrogen and has fewer side effects, but its contraceptive effect is worse than that of estrogen and estrogen combination preparations, and the incidence of non-menstrual bleeding is higher. Rarely used.