How long can sperm survive in a woman's body?

Since women's ovulation periods vary and the timing of sexual intercourse is not fixed, the sperm must wait for the egg to increase the chance of meeting. Therefore, the length of time sperm survives in the female reproductive tract is closely related to fertility.

1. Sperm retention time in the female reproductive tract:

The pH of vaginal acidic secretions is usually 3.5-4. Although theoretically fertilization can occur as long as there is one living sperm, in reality, due to the acidic environment of the vagina, most sperm die soon after entering the vagina. Only with the buffering of a certain amount of semen can the survival time of a very small number of sperm with strong vitality be extended, giving them the opportunity to enter the uterus and fertilize.

Without the sacrifice of a large number of sperm, without a certain amount of semen buffering to improve the acid-base environment in the vagina, a single sperm or a very small number of sperm would not be able to survive and fertilize in the acidic environment of the vagina.

Generally speaking, the survival time of sperm in the vagina is: 90% die 2 hours after sexual intercourse; after 36 hours, even the dead ones cannot be seen. In a pregnant woman's vagina, the stronger the acidity, the faster the sperm die.

2. Sperm retention time in the cervix:

Changes in the acidity and alkalinity of cervical mucus have a great impact on sperm penetration. When the pH is less than 6.5, sperm stops moving. At pH 7, it has slight penetration ability. At pH 7.5, the penetration ability is normal. At pH 8.2, the penetration ability is even stronger.

There is a lot of mucus blockage at the external opening of the cervix, which causes many sperm to be unable to penetrate and die outside. Cervical mucus is thick and tough just after menstruation; as ovulation approaches, the mucus becomes more abundant, clearer, and more stringy due to the increase of estrogen in the blood; during ovulation, the mucus is more abundant, clearer, and flows out, making it easier for sperm to penetrate.

Sperm penetrates cervical mucus by relying on the hydrolysis of enzymes. Trypsin-containing chymotrypsin and hyaluronidase can hydrolyze cervical mucus, reduce viscosity, and eliminate sticky thread formation, which is conducive to the passage of sperm.

Generally speaking, the survival time of sperm in the cervix is: inside the cervix, sperm can be found in the cervical mucus 15 minutes after sexual intercourse; one hour later, sperm enters the internal opening; inside the uterine cavity, sperm is found in the uterine cavity 1 hour after sexual intercourse, 6 hours later, all are active sperm, 12 hours later, 5/6 of the sperm are still alive, 36 hours later, 1/4 of the sperm are still alive, and after three days, there are no live sperm. But sometimes some individual sperm survive particularly long.

3. Sperm retention time in the fallopian tube:

In the fallopian tube, there are active sperm 14 hours after sexual intercourse, and sometimes there are still active sperm 35 days later. Generally, those after 14 days are the most active, and some enter the abdominal cavity. Those that move slowly are pushed back into the uterine cavity by the ciliary flow.