Semen pH is an indicator of acidity or alkalinity of the seminal fluid. Under normal conditions, semen is slightly alkaline with a pH ranging from 7.2-8.0 according to WHO guidelines.
Semen helps nourish and protect sperm. Having the optimum pH level in semen is important to keep sperm cells healthy and mobile, while the alkalinity helps to neutralize the acidic vaginal environment. If the semen pH is abnormal, either acidic or too alkaline, it can interfere with the sperm quality, causing subfertility or infertility.
FertilitySmarts explains Semen pH
pH is a measurement of hydrogen ions in a solution. The pH value indicates if the solution is acidic or basic. pH can range from 0-14, 0 being the strongest acid and 14 the strongest base. Pure water is considered neutral and has a pH of 7.
Semen is produced mainly by the seminal vesicles, two glands located behind the bladder and the prostate. Secretions from the seminal vesicles are basic, while prostrate secretions are slightly acidic, so semen formed by mixing of these fluids remains slightly alkaline and provides the optimum environment for sperm.
Vaginal fluid is acidic with a pH ranging from 3.5-4.5. This is largely due to lactic acid produced by beneficial bacteria growing in the vagina. The acidic pH prevents disease-causing bacteria and fungi from growing and keeps the vagina healthy. However, this environment is not ideal for sperm, therefore, sperm rely on the ability of the semen (along with cervical mucus) to neutralize the vaginal acid and achieve a more neutral pH, so sperm can effectively swim across the vagina and uterus to the fallopian tubes to fertilize the egg.
What impacts semen pH levels?
Abnormal semen production, such as infection or seminal vesicle blockage can cause suboptimal semen pH levels.
How is it assessed?
If male subfertility is diagnosed or suspected, a semen analysis is indicated. Semen pH is routinely tested during a semen analysis, so abnormalities in pH can be detected.
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Zhou J, et al.
The Semen pH Affects Sperm Motility and Capacitation.