After a man ejaculates, the semen needs to liquefy before it can swim into the vagina, and the liquefaction time varies widely among individuals, mostly within 5 minutes. Within a few minutes, if the woman wishes to use vaginal douching or other methods to achieve contraception, it is unrealistic and unreliable. An intrauterine device (IUD) or a long term oral short-acting oral contraceptive pill is much more effective. Usually, the condom device is about 80% effective, while the morning-after pill is about 80%-90% effective, and the short-acting oral contraceptive pill and IUD, the contraceptive efficiency is more than 99%. Nowadays, efficient and scientific contraceptive measures are promoted, which currently include sterilization, the pill and the placement of IUDs. If there is a desire to conceive, intercourse can be arranged during ovulation to increase the chances of conception.