Menstruation is a natural physiological process where the body sheds the uterine lining, resulting in a flow of blood and tissue. Many people who menstruate wonder about the practicalities of swimming or bathing without internal protection like a tampon or menstrual cup. This common question often stems from the observation that flow seems to stop entirely upon entering the water. Understanding the science behind this phenomenon can provide clarity and allow for informed decisions about water activities during a period.
Does Menstrual Flow Truly Stop
The process of menstruation does not actually stop when the body is submerged in water. The internal biological mechanism, which involves the uterus shedding its endometrial lining, continues uninterrupted, regardless of the external environment. This shedding is governed by hormonal signals and uterine contractions.
The perception that the period has stopped is due to the flow being temporarily inhibited or dramatically slowed down. Menstrual fluid continues to collect within the vaginal canal while submerged, and the temporary pause in external flow is solely a physical effect related to external forces, not a biological cessation of the cycle.
How Water Pressure Affects Flow
The apparent cessation of flow is a direct result of simple physics, specifically the principle of hydrostatic pressure. Hydrostatic pressure is the force exerted by a fluid at equilibrium at a given point. When the body is submerged, the surrounding water exerts an external pressure against the vaginal opening. This external water pressure acts as a temporary counter-force that is greater than the pressure inside the vagina pushing the menstrual fluid out, effectively creating a seal. Conversely, actions that increase internal abdominal pressure, such as a forceful cough or sneeze, may temporarily overcome the external water pressure and cause a small amount of fluid to escape.
Exiting the Water and Hygiene Considerations
When a person exits the water, the external hydrostatic pressure is immediately removed, and gravity once again becomes the dominant force. This sudden removal of the counter-pressure often leads to a noticeable gush of collected menstrual fluid that had been temporarily held inside the vaginal canal.
The risk of blood contamination in large bodies of water like pools or the ocean is minimal due to the high volume of water and rapid dilution. Public swimming pools use chlorine and other chemicals designed to maintain water quality and neutralize bodily fluids. For personal hygiene, it is advisable to have a dark towel or an immediate change of clothes ready upon exiting the water, though using a menstrual cup or a tampon provides a more secure and discreet experience.