A bladder infection, medically referred to as a lower urinary tract infection, usually develops when bacteria travel from the gut area near the urethra, enter the urethra, and then multiply in the bladder. The culprit in most cases is Escherichia coli, often abbreviated as E. coli. This is a bacterium that occurs naturally in the gut, where it's usually harmless, but it can cause symptoms when in the wrong place.
Women get bladder infections considerably more often than men. The main explanation is anatomical: a woman's urethra is shorter than a man's, meaning bacteria have a shorter distance to travel to reach the bladder. In addition, the urethra, vagina, and anus are located close together. This makes it easier for gut bacteria to end up near the urethra. More than half of all women will have at least one bladder infection in their lifetime.
A number of factors can play a role in the development of a bladder infection:
Sexual activity
In younger women, factors such as a new sexual partner, more frequent vaginal sex, and the use of spermicide-based contraception are associated with a higher likelihood of recurring urinary tract infections. That doesn't mean sex is "the cause," but it does mean sexual contact can make it easier for bacteria to move toward the urethra.
Menopause
After menopause, the decline in estrogen plays a particularly important role. Hormonal changes also affect the vaginal environment: it becomes less acidic, and the share of lactobacilli can be disrupted. This makes it easier for bacteria to establish themselves. Other factors, such as urinary leakage, a prolapsed bladder, or urine that remains after urinating, can also contribute to recurring symptoms.
Diabetes
Several studies show that women with diabetes have a higher likelihood of recurring urinary tract infections. Glucose in the urine may play a role here, among other things, as it can create a more favorable environment for bacteria.
Pregnancy
A lot changes in the body during pregnancy. The growing uterus can put pressure on the bladder, and progesterone causes the urinary tract to work somewhat more slowly. As a result, urine can sometimes sit for longer, making it easier for bacteria to grow. Because urinary tract infections during pregnancy can have consequences for both mother and child, urine is monitored extra closely during prenatal checkups.
Not drinking enough
Not getting enough fluids can also play a role. Drinking less often means urinating less often, giving bacteria more time to attach and multiply. In women who drink little and get bladder infections often, drinking more water can help reduce the number of infections.
It's important to realize that there's rarely a single identifiable cause. For most women, a bladder infection results from a combination of anatomy, behavior, hormones, and sometimes medical factors. That also makes it a topic nobody needs to feel ashamed about: it happens to a great many women, regardless of hygiene or lifestyle.
