First, in the young and exciting environment of men, the amount of semen injected is generally at a high level (generally 2-6 ml). Although there is no ejaculation in the vagina, due to the large amount of semen, it may partially flow into the vagina. Although women have hymen to block the vaginal opening, there are many gaps in the normal hymen. As long as a drop of semen flows in the vaginal opening, it will enter the uterus along the ovulation tube, which may lead to pregnancy.
Secondly, sperm is not destroyed by the acidic environment in the vagina, which is also an important cause of pregnancy. During ovulation, the cervical secretion increases to 0.5 ml per day (0. 1 ml per day in other periods), and the liquid secreted by the cervix is weakly alkaline, which can neutralize the acidic environment in the vagina, thus protecting the sperm remaining in the vagina and prolonging its life. Therefore, even if there is no direct sexual intercourse, it may lead to pregnancy.
Why does IVF pregnancy happen? You know, men have 200 million or 300 million sperm at a time. Sperm can shoot up to 50 cm, and sperm activity 1 hour can run 65 kilometers. Sperm near the vagina can enter the uterine cavity within 1.5 to 3 minutes and reach the fallopian tube within 30 minutes. Sperm can survive for 24 to 48 hours in vitro.
Physiologically, teenage girls are the most fertile period, and as long as they ovulate, the pregnancy rate is also the highest; When sexually excited, vaginal secretions can flow outside to mix with semen, and sperm can swim into vagina, cervix and uterus along the mixed solution. At this time, the egg that has just returned from the fallopian tube will become pregnant. However, if the semen of interrupted sexual intercourse remains in the woman's vagina and is not washed immediately, it is also possible that the sperm will survive in a warm and humid environment.
From this point of view, it is also possible to get pregnant without direct sexual intercourse. Therefore, gynecologists remind parents to pay attention to the sex education of adolescent children.