What are factors related to male fertility? How many days can sperm survive inside a woman?

For most people who are trying to conceive (TTC), sperm count may be the first indicator appearing in their mind, which is related to male fertility. According to World Health Organization (WHO), typical count should be around 40 million per 2ml semen sample. Besides sperm count, healthy sperm motility and morphology (correct shape and structure) are also important to male fertility.

Given normal male fertility, the life of sperm inside a woman depends on the following factors:

• Individual longevity of sperm.
• The internal metabolic capacity of sperm.
• The environment of the vagina (body temperature, PH level and etc.)
• The presence and quality of cervical mucus.
• The ability of the sperm to swim to cervix and into uterus.
• The presence of sperm antagonists like immunity securing white blood cells.

If all of above conditions are perfect, sperm may be able to live up to seven days, which is around a quater of menstrual cycle. However, in most cases, some factors may decrease sperm longevity or prevent sperm movement. If the sperm gets no luck to swim into womb, it can only live for a few hours. If the sperm gets to move into uterus, it may survive longer. Normally, it is expected that the sperm can survive just one day or two.

Obviously, more and more sperm die as time goes on and thus possiblility of conception gest lower. Therefore, the ideal TTC strategy is to make love daily during the fertile time window.