It is not uncommon in medicine for pregnancy to occur simply from sexual organ contact. Generally speaking, during pregnancy in this case, the hymen is basically kept intact. Even if there is no actual sexual intercourse, the woman may become pregnant. This chance is relatively small. The main reason for this is that men ejaculate outside the vagina during sexual excitement, but some sperm have already entered the vagina, and the woman happens to be in the ovulation period. The man is young and strong and in an exciting environment, the man ejaculates. The amount of semen must be at a high level. Therefore, although there is no ejaculation in the vagina, part of the semen may flow into the vagina due to the large amount of semen. Although the woman has a hymen blocking the vaginal opening, there are many gaps in the normal hymen. As long as there is When a drop of semen flows into the vaginal opening, the sperm will enter the uterus along the ovulatory tube and mate with the egg, causing the woman to become pregnant.

Especially when women are in ovulation and orgasm, they are more likely to become pregnant. During normal sexual intercourse, semen is stored in a place called the posterior cavity (semen pool) deep in the vagina, which is closest to the cervix. This makes it easy for sperm to pass through the cervix and uterus to the fertilization site in the outer third of the fallopian tube. If the sperm fails to enter the cervix, it can only survive in the acidic environment of the vagina for a short period of 6-8 hours. Usually a man's sperm must be very healthy and have strong vitality to conceive. The fact that the sperm is not destroyed by the acidic environment in the vagina is due to the woman's ovulation period. During the ovulation period, the secretion of the cervix increases, and when sexual desire is highly excited, the amount of secretion can continue to increase. The liquid is weakly alkaline, which can neutralize the acidic environment of the vagina, thereby protecting the sperm remaining in the vagina and extending its life. In addition, the sperm needs to undergo a "capacitation" process in order to be able to fertilize. " process, the capacitation of sperm usually starts from the cervix, but when the woman's sexual desire is strong, a large amount of liquid secreted by the cervix flows into the vagina. At this time, the capacitation of sperm can be advanced. After capacitation, The sperm appears healthier and livelier, and its tail swings faster, showing a specific "whipping-like" movement pattern, allowing it to not only survive in the vagina, but also swim into the uterus at a faster speed, thus resulted in conception.