A standard urinary tract infection that stays in the bladder is unlikely to cause infertility on its own. But when a UTI goes untreated and bacteria spread beyond the bladder into the reproductive organs, the resulting damage can make it harder to conceive. This applies to both women and men, though the pathways differ.
The key distinction is between a lower UTI (confined to the bladder and urethra) and an infection that climbs upward. Most UTIs are treated quickly and resolve without lasting harm. The fertility risks emerge when infections become chronic, recurrent, or are ignored long enough for bacteria to reach the kidneys, fallopian tubes, uterus, or male reproductive tract.
How Infection Spreads Beyond the Bladder
The most common UTI-causing bacterium, E. coli, doesn’t just affect the urinary system. When it migrates into the reproductive tract, it can trigger inflammation in the fallopian tubes, contribute to blockages, and even promote endometriosis, a condition where uterine tissue grows outside the uterus. E. coli infections can also interfere with fertilization itself, disrupting the moment when egg and sperm join to form an embryo.
This migration is more likely when a UTI is left untreated for days or weeks, or when someone experiences repeated infections over months. Each round of infection and inflammation adds to the cumulative damage in the reproductive tract.
Fallopian Tube Damage in Women
The most direct path from infection to infertility in women runs through the fallopian tubes. When bacteria cause chronic or repeated inflammation in the reproductive tract, scar tissue can form inside or around the tubes. In some cases, this scarring progresses to tubal occlusion, meaning the tubes become partially or fully blocked. Since the fallopian tubes are where fertilization normally happens, any blockage can prevent sperm from reaching the egg or stop a fertilized egg from traveling to the uterus.
Research published in the journal Fertility and Sterility found that women with a predisposition to excessive scarring (similar to the tendency that causes raised, thickened scars called keloids on the skin) may be especially vulnerable. In these women, the inflammatory response triggered by chronic or repeated infections generates more adhesions and scar tissue than usual, increasing the likelihood of tubal blockage. This excessive scarring response isn’t limited to the skin. It can also occur in the reproductive tract, raising the frequency of infertility in women who are prone to it.
It’s worth noting that sexually transmitted infections like chlamydia are a far more common cause of tubal scarring than UTIs. Chlamydia is considered one of the principal causes of tubal injury worldwide. Part of the reason UTIs sometimes get blamed for infertility is that UTI symptoms can overlap with STI symptoms, and the two can coexist without the person realizing they have both. If you’ve been dealing with recurrent urinary symptoms and are having trouble conceiving, testing for STIs alongside UTI cultures gives a much clearer picture of what’s going on.
Effects on Male Fertility
In men, urinary tract infections can travel into the reproductive system through a slightly different route, reaching the epididymis (the coiled tube behind each testicle where sperm mature) or the prostate. When bacteria from a UTI cause epididymitis, the acute infection typically leads to a temporary drop in sperm quality. What’s less well known is that even after the infection clears completely with antibiotics, persistent damage to sperm is not uncommon.
A review in the journal World Journal of Urology examined how urogenital infections affect semen quality across different parts of the male reproductive tract. The findings were notable: chronic urethritis (ongoing inflammation of the urethra) can silently damage sperm quality without causing obvious symptoms. Men with chronic pelvic pain syndrome showed abnormal sperm shape and changes in the fluid that carries sperm. And in men who had recovered from epididymitis, detrimental effects on semen persisted in a significant number of cases even after bacteriological testing showed the infection was gone.
E. coli specifically causes inflammation and problems with sperm when it infects the male genital tract, potentially reducing a man’s ability to get a partner pregnant. The longer the infection lingers, the greater the chance of lasting reproductive effects.
Recurrent UTIs Carry More Risk Than a Single Episode
A single UTI that’s caught early and treated with a short course of antibiotics is very unlikely to affect your fertility. The real concern is with infections that are left untreated for extended periods, infections that keep coming back, or infections that have already spread to the kidneys or reproductive organs by the time treatment begins.
Each episode of infection triggers an inflammatory response, and inflammation is the mechanism that causes scarring and tissue damage. One mild inflammatory episode usually heals cleanly. But repeated rounds of inflammation in the same tissue can lead to the kind of cumulative scarring that narrows or blocks reproductive passages. This is true for both fallopian tubes in women and the epididymis or vas deferens in men.
People who get frequent UTIs (generally defined as three or more in a year) should pay particular attention to getting each infection fully treated. Stopping antibiotics early because symptoms improve, or relying on home remedies instead of proven treatment, leaves bacteria alive and capable of causing deeper infection.
What Actually Protects Your Fertility
The most protective step is straightforward: treat UTIs promptly and completely. Most uncomplicated bladder infections resolve within a few days of starting antibiotics, and at that stage the infection hasn’t had time to cause reproductive damage.
If you’re experiencing recurrent UTIs, getting a proper culture each time matters. A urine culture identifies the specific bacteria involved and confirms which antibiotics will work against it. This is especially important because antibiotic-resistant strains of E. coli are increasingly common, and using the wrong antibiotic gives bacteria more time to spread.
For anyone struggling with fertility and a history of frequent urinary or genital tract infections, comprehensive testing that includes STI screening alongside standard UTI workups provides the most useful information. Chlamydia and gonorrhea can cause symptoms that mimic or overlap with UTIs, and these STIs carry a much higher and more direct risk of tubal damage and infertility. Identifying and treating the right infection is the single most important factor in preventing long-term reproductive harm.