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Why are urinary tract infections much more common in women than in men?

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The most common cause of urinary tract infection is invasion into the urethra of Escherichia coli, a type of bacterium that normally inhabits the bowel. — urinary tract infection The most common cause of urinary tract infection is invasion into the urethra of *Escherichia coli*, a type of bacterium that normally inhabits the bowel.

Urinary tract infections (UTIs) are significantly more common in women than in men, with women being affected approximately 30 times more often. The primary anatomical factor contributing to this disparity is the length of the urethra.1

In women, the urethra is much shorter—measuring only about 4 cm (1.5 inches)—compared to the male urethra, which is approximately 18 to 20 cm (7 to 8 inches) long. This shorter distance makes it easier for microorganisms, such as bacteria, to travel into the bladder and cause an infection.21

Several other factors also increase susceptibility in women:
* Sexual activity: Intercourse can facilitate the transmission of bacteria, and the use of diaphragms for contraception is associated with higher risk.1
* Pregnancy: Pressure on the urinary tract can lead to partial stagnation of urine, creating an environment conducive to infection.1
* Postmenopause: Decreasing levels of estrogen can cause the thinning of the vaginal epithelium, which reduces the body's natural defenses against bacterial invasion.1
* Biological markers: Evidence suggests that certain antigens in the P blood group system may act as adhesion sites for bacteria, further facilitating infection in some women.1