The question of whether menstrual flow continues when submerged in water is common, often leading to confusion about swimming while menstruating. The internal biological process of shedding the uterine lining does not stop just because the body is in water. However, the external manifestation of the flow, the blood leaving the body, is temporarily altered by the surrounding water. Understanding this dynamic involves looking at basic physics and body mechanics, which clarifies concerns many people have about water activities during their cycle.
The Physics of Menstrual Flow Underwater
The appearance that menstrual flow stops or pauses when entering water is entirely due to a principle of physics called hydrostatic pressure. This is the pressure exerted by the surrounding water when the body is submerged, acting against the vaginal opening.
This external pressure counteracts the force of gravity, which normally aids the downward and outward flow of menstrual fluid when a person is standing or sitting. The water effectively creates a temporary barrier that resists the exit of the fluid. This mechanism does not halt the shedding process in the uterus, but it momentarily balances the internal flow dynamics, making it seem as if the period has stopped.
If a person coughs, sneezes, or laughs while submerged, the change in internal abdominal pressure can momentarily overcome the external hydrostatic pressure. This shift in pressure may cause a small amount of fluid to be released into the water, particularly if the flow is heavy. Once a person exits the water and the external pressure is removed, the normal flow resumes as gravity again becomes the dominant force.
Practical Management for Water Activities
Since hydrostatic pressure only slows the flow and is not a guaranteed preventative measure, internal collection methods are the most effective way to manage menstruation during water activities. External products like traditional pads or panty liners should be avoided because they are designed to absorb liquid and will quickly become saturated with water, rendering them ineffective for collecting menstrual fluid. They can also lose their adhesive quality and become uncomfortable or displaced in the water.
Tampons are a common and effective choice for swimming because they are inserted internally and absorb the fluid before it exits the body. It is recommended to use a low-absorbency tampon and change it immediately after exiting the water, as tampons can absorb some of the surrounding water and chemicals, like chlorine.
Menstrual cups and discs are also highly suitable options, as they collect fluid rather than absorb it, creating a seal that prevents leakage and does not absorb pool or ocean water. These internal methods provide containment and comfort, ensuring that any potential leakage is managed before it can occur in the water. Prompt removal or changing of the product upon leaving the water is an important hygiene step, as the flow will restart once the hydrostatic pressure is gone.
Dispelling Myths About Swimming While Menstruating
Concerns about swimming while menstruating often stem from misinformation regarding hygiene and safety. A common anxiety is that a small amount of menstrual fluid in a swimming pool will contaminate the water for others.
In reality, modern swimming pools are treated with chemicals, such as chlorine, specifically to neutralize and sanitize bodily fluids, including sweat and urine. The small volume of menstrual fluid that might be released, especially when using an internal product, is quickly diluted and treated by the pool’s established filtration and chemical maintenance systems. Health organizations confirm that there is no evidence of increased health risk from swimming in a properly maintained pool while menstruating. The pool’s chemical balance is designed to handle far more concerning contaminants.
Another pervasive myth involves the fear that menstrual blood attracts sharks in open water settings, like the ocean. There is no scientific evidence to support the idea that the volume or composition of menstrual blood draws sharks any more than other minor cuts or bodily fluids. The amount of blood lost during menstruation is significantly less than what might be released from a small wound, and sharks are not specifically attuned to human blood as a primary food source. Swimming and water activities remain safe during menstruation, and there is no medical reason to avoid them.