避妊法

Vasectomy is a surgical procedure that severs and seals the vasa deferentia, preventing sperm from mixing with semen during ejaculation. The procedure does not affect testosterone production or sexual function, as the testes continue producing hormones normally. Vasectomy is highly effective, with a success rate near 99.85%, though rare cases of spontaneous reconnection can occur.

Tubal ligation is the most common female sterilization method, involving closure and severance of the fallopian tubes using clips, clamps, or cutting and burning techniques. This prevents eggs from traveling to the uterus for fertilization. The Essure procedure, which used metallic coils to promote scar tissue formation, has been discontinued in many countries due to reported complications including chronic pain and device migration.

Combined oral contraceptives contain estrogen and progestin, which suppress ovulation to prevent pregnancy. Progestin-only pills work differently by thickening cervical mucus to hinder sperm mobility. Hormonal methods also offer additional benefits like cycle regulation and reduced risks of certain cancers, though they may not be suitable for smokers due to increased cardiovascular risk.

Copper IUDs create an inflammatory response in the uterine lining that is toxic to sperm and eggs, preventing fertilization. Hormonal IUDs release progestin, which thickens cervical mucus to block sperm, thins the uterine lining, and may suppress ovulation. Both are highly effective long-term contraceptive options, though potential side effects include discomfort, expulsion, or irregular bleeding.

Barrier methods including male and female condoms, diaphragms, and cervical caps physically prevent sperm from reaching the egg. Condoms uniquely offer protection against sexually transmitted infections in addition to contraception. These methods are often combined with spermicides, substances that neutralize sperm on contact, to increase effectiveness.

The sympto-thermal method, or STM, is a periodic abstinence strategy that tracks multiple fertility indicators including basal body temperature and cervical mucus characteristics to identify fertile periods. Success rates vary due to menstrual cycle irregularity, making it less reliable than surgical or hormonal methods. Abstaining from sex during identified fertile days can prevent pregnancy when cycles are regular.

Emergency contraception pills should be used shortly after unprotected intercourse to prevent pregnancy. While hormonal birth control methods like combined pills and patches are highly effective for regular use, emergency options provide a backup when primary contraception fails. Long-term methods such as the Depo-Provera injection, lasting three months, offer more consistent protection than emergency approaches.