Different positions of intercourse do have the effect of promoting or avoiding pregnancy. Positions that facilitate ejaculation deep in the vagina help conception. It is best to keep the ejaculated semen concentrated at the cervical opening and the penis remains erect while remaining in the vagina, acting as a plug. If the semen is not ejaculated deep in the vagina and quickly flows out of the body, it is not easy to conceive. Sperm are anaerobic and lose their vitality quickly when they encounter oxygen. When small bubbles are created in the vagina, the sperm are attracted for a few seconds and then lose their vitality and are crippled. When the penis continues to thrust after ejaculation, more air enters the vagina and small bubbles are produced, which prevents conception. Therefore, in order to increase the chance of conception, it is not advisable to lift and thrust before and after ejaculation, but to thrust as deep as possible at the moment of ejaculation, and to leave the penis in the vagina for a while after ejaculation before carefully withdrawing it. It is not necessary to have an orgasm to conceive, but the presence of an orgasm can increase the chances of conception. The pressure inside the uterine cavity drops sharply to negative pressure after orgasm, and the process of returning to normal produces suction, which makes it easy for sperm to swim in; the position of the uterus rises during orgasm, making the cervical opening closer to the semen; orgasm increases the secretion of vaginal fluid and increases the PH value, which is more suitable for sperm activity. The timing of sexual intercourse is also the key to improving the chances of conception. The human egg has a maximum life span of 12 to 24 hours after ovulation. The duration of sperm viability is influenced to a greater extent by the environment in the female reproductive tract. If sperm remain in the vagina for 8 hours after ejaculation, they will die; if they enter the cervix and the mucus in the cervical canal is of a suitable nature and pH, they can survive for 3 (or possibly 5) days. Therefore, the maximum time frame for conception is 4 days. Therefore, it is generally advisable to allow the sperm to enter the female reproductive tract a few days earlier to wait for the egg and meet it, so that the chances of fertilization are higher.