How long is the survival period of sperm?

If a man and a woman have sex without taking proper contraceptive measures, and the woman is ovulating, it is very easy to get pregnant. Male sperm has a certain survival period, so it is possible to get pregnant within a few days. So how long is the survival period of sperm? The survival time of sperm is related to the acidity of the female vagina. Most of them are from two hours to three days, but almost most sperm will die within 36 hours.

1. Sperm residence time in the female reproductive tract

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

Without the sacrifice of a large number of sperm, and without a certain amount of semen buffering to improve the acid-base environment in the vagina, it is impossible for a single sperm or a very small number of sperm to survive and fertilize in the acidic environment of the vagina.

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

2. Sperm retention time in the cervix

Changes in the pH of cervical mucus have a great impact on sperm penetration. When the pH is less than 6.5, sperm activity stops, at pH 7, there is a slight ability to penetrate, at pH 7.5, the ability to penetrate is normal, and at pH 8.2, the ability to penetrate is stronger.

There is a lot of mucus blocking the external opening of the cervix, which prevents many sperm from penetrating and causing them to die outside. Cervical mucus is thick and tough just after menstruation; near ovulation, due to the increase of estrogen in the blood, the mucus becomes more abundant, clearer, and more stringy; during ovulation, the mucus is more abundant, clearer, and flows out, making it easier for sperm to penetrate.

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

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 that are 14 days old are the most active, and some enter the abdominal cavity. Those that move slowly are pushed back into the uterine cavity by the cilia.