Pregnancy

UTIs in Pregnancy: Small Infection, Real Stakes

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A urinary tract infection in pregnancy gets treated promptly because a minor bladder infection can spread to the kidneys and increase the chance of preterm labor. Pregnancy makes the urinary tract more vulnerable, so prenatal visits include a routine urine test even without symptoms. A urine culture confirms whether treatment is needed.

Last updated: July 2026

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Why is a UTI a bigger deal in pregnancy?

Pregnancy changes the urinary tract in ways that let a routine infection turn serious. Rising progesterone relaxes the muscular walls of the ureters, and the growing uterus presses on the bladder, so urine drains more slowly and bacteria have more time to multiply. According to NICE antenatal guidance, treating urinary infection in pregnancy lowers the risk of a kidney infection and its complications 1. Outside pregnancy, a mild bladder infection is often uncomplicated and sometimes even watched. During pregnancy the same infection carries a higher chance of reaching the kidneys, in some estimates up to 1 in 3 of untreated cases, and has been linked with preterm birth, so the threshold to treat is deliberately lower.

What is asymptomatic bacteriuria?

Asymptomatic bacteriuria means bacteria are growing in the urine without causing any noticeable symptoms. Outside pregnancy, this finding is usually left alone, because treating it offers little benefit and can encourage antibiotic resistance. In pregnancy the calculus flips: according to NICE, screening for and treating asymptomatic bacteriuria reduces the chance that it progresses to a symptomatic kidney infection 1. Roughly 2 to 10 percent of pregnant people have bacteria in the urine without symptoms, and a share of untreated cases go on to a kidney infection. That is the main reason a urine sample is collected early in pregnancy and cultured in a lab, rather than judged by how you feel.

How do prenatal visits screen for UTIs?

Prenatal visits build in urine testing from the very first appointment, usually before 12 weeks. According to the Office on Women's Health, a urine sample is a standard part of prenatal care and can flag infection, protein, or sugar 2. Early in pregnancy a urine culture checks for hidden bacteria, while later visits often use a quick dipstick. If a culture grows bacteria, a clinician selects an antibiotic chosen for use in pregnancy and may recheck the urine afterward to confirm it cleared 1. Symptoms such as burning or urgency overlap with a yeast infection or vaginal irritation, so a lab test rather than a guess guides treatment 3. Reporting new symptoms between visits helps catch infection sooner.

What are the warning signs of a kidney infection?

A kidney infection, or pyelonephritis, is the complication prenatal screening is designed to prevent. Warning signs include fever and chills, pain in the side or back below the ribs, nausea or vomiting, and worsening burning with urination. According to NICE, pyelonephritis in pregnancy raises the risk of preterm labor and other complications, which is why it is treated urgently, often in a hospital 1. Symptoms of a lower urinary tract infection, such as burning, urgency, and cloudy or strong-smelling urine, are milder but still worth prompt attention. Across the lifespan, urinary infections are common in adolescence, again in pregnancy, and once more after menopause, yet pregnancy is the stage where prompt treatment matters most for two people at once.

When a UTI in pregnancy needs a clinician

Any urinary symptom in pregnancy is a reason to check in with a clinician rather than wait it out. Burning, urgency, cloudy or bloody urine, low pelvic pressure, or a sense that something is off all deserve a same-week call. Fever, back or flank pain, chills, or vomiting suggest the infection may have reached the kidneys and warrant urgent evaluation. Because a urine culture is quick and treatment options that are safe in pregnancy exist, there is little reason to tolerate symptoms or to ride out an infection at home. A short course of the right antibiotic almost always clears the infection well before it becomes a threat to the pregnancy. Gale can help you prepare for that conversation and track what to mention at your next prenatal visit.

Common questions

Bacteria in the urine without symptoms, called asymptomatic bacteriuria, is treated in pregnancy because it can progress to a kidney infection that raises the risk of preterm labor. Outside pregnancy this finding is usually left alone, but the stakes are higher when you are expecting, which is why early urine testing is routine.

An untreated urinary infection that climbs to the kidneys has been linked to preterm labor and other complications. Prompt treatment lowers that risk, which is why clinicians screen and treat readily in pregnancy. A simple bladder infection caught and treated early is very unlikely to cause harm.

Yes, several antibiotics are considered appropriate to use in pregnancy, and a clinician chooses the option and timing based on your stage of pregnancy and the bacteria found on culture. Leaving an infection untreated generally carries more risk than a suitable antibiotic does.

Burning, urgency, and cloudy urine suggest a UTI, but similar symptoms can come from a yeast infection or vaginal irritation. Because the symptoms overlap, a urine test rather than a guess is the reliable way to tell. Reporting symptoms to your prenatal team lets them test and treat the right thing.

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When urinary symptoms in pregnancy need urgent care

  • —Fever, chills, or back and side pain with urinary symptoms may signal a kidney infection and is a reason to seek urgent evaluation
  • —Nausea or vomiting alongside burning urination is a reason to seek same-day clinician review
  • —Blood in the urine is a reason to contact your prenatal team promptly
  • —Regular tightening or cramping before 37 weeks with a suspected infection is a reason to seek urgent labor and delivery review
  • —Being unable to keep down fluids while feeling feverish is a reason to seek immediate care

If you have a fever with back or side pain, cannot keep down fluids, or have regular contractions before 37 weeks, seek urgent evaluation right away through your prenatal team, an urgent care clinic, or the nearest emergency room.

This article is general health education, not medical advice. Whether you have a urinary infection and how it should be treated in pregnancy is a decision for a clinician such as a primary care provider, nurse practitioner, midwife, or obstetrician.

References

  1. 1.National Institute for Health and Care Excellence (2024). Antenatal care (NG201). National Institute for Health and Care Excellence (NICE). link ✓Routine screening of urine for asymptomatic bacteriuria in early pregnancy and treatment to reduce the risk of pyelonephritis and related complications, including preterm labor
  2. 2.Office on Women's Health (U.S. HHS) (2025). Prenatal care. Office on Women's Health (womenshealth.gov), U.S. HHS. link ✓A urine sample as a standard part of each prenatal visit, used to check for infection, protein, and sugar
  3. 3.MedlinePlus (National Library of Medicine) (2024). Vaginitis. MedlinePlus, U.S. National Library of Medicine (NIH). link ✓Overlap between urinary and vaginal symptoms and the value of testing to distinguish a UTI from vaginitis or a yeast infection

3 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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