Urinary Tract Infections in Pregnancy

When to call

This section is first because with a UTI in pregnancy, the timing of the call is the treatment.

Same day, if you have symptoms. ACOG could not be clearer: "Call your ob-gyn right away if you have symptoms of a UTI. If you cannot reach your ob-gyn, go to an urgent care clinic. Do not wait for treatment." The NHS lists pregnancy as a reason to ask for an urgent GP appointment rather than trying self-care first.

Urgently — today, not tomorrow — if any of these are true, because they suggest the infection has reached a kidney. The NHS lists: a very high temperature, or feeling hot, cold or shivery; a very low temperature below 36C (96.8F); pain in the lower tummy or in the back, just under the ribs; blood in your pee; feeling or being sick; not having had a pee all day. Tommy's gives the same list with a temperature threshold above 37.5C (99.5F) and adds that these suggest infection has spread to your kidneys.

Hospital assessment is what NICE's Clinical Knowledge Summaries advise for a pregnant woman with suspected UTI who has "severe systemic symptoms or signs suggesting a possible serious or life-threatening complication, such as pyelonephritis or sepsis", who cannot tolerate or keep down treatment at home, or where there is "clinical suspicion of impending labour".

Call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, or 111 in New Zealand) or go to an emergency department if you are confused, drowsy or having difficulty speaking. The NHS lists this as a possible sign of sepsis.

Go back if it is not improving. CKS advises telling women to "seek urgent medical review if symptoms worsen rapidly or significantly at any time, or do not improve within 48 hours of starting antibiotic treatment". Two days is the checkpoint.

Why this page leads with the phone call

Because the consequences of a delayed UTI in pregnancy are not theoretical, and the treatment is ordinary.

The Cochrane review of asymptomatic bacteriuria — bacteria in the urine without symptoms — states that it "occurs in 2% to 15% of pregnancies" and that "if left untreated, up to 30% of mothers will develop acute pyelonephritis", a kidney infection. NICE's CKS lists the complications of lower UTI in pregnancy as an "increased risk of preterm delivery, low birth weight baby, or acute pyelonephritis". ACOG puts the frequency at "about 8 in 100 pregnancies" and adds that if a kidney infection develops "it can cause severe complications, including sepsis, blood clotting problems, and trouble breathing".

Against that, the treatment is a urine sample and a course of antibiotics. That asymmetry — small intervention, meaningful risk if skipped — is the entire argument of this page.

Why your urine gets tested when you feel completely fine

This is the part that puzzles people. ACOG explains it directly: "Your urine should be tested for bacteria during one of your first prenatal care visits. Your urine may have bacteria even if you don't have symptoms. By treating a UTI before symptoms appear, you can avoid the possible problems it can cause."

NICE's CKS describes the same practice, with a midstream urine sample sent for culture at the booking appointment for women assessed as intermediate or high risk, and antibiotic treatment when bacteriuria is found.

Does treating it help? The Cochrane review pooled 15 studies involving over 2000 women. Antibiotic treatment "may reduce the incidence of pyelonephritis" (average risk ratio 0.24, 95% CI 0.13 to 0.41), and may reduce preterm birth (RR 0.34, 95% CI 0.13 to 0.88) and low birthweight (average RR 0.64, 95% CI 0.45 to 0.93). The honest caveat, which the reviewers make themselves, is that all three findings are low-certainty evidence: only one of the 15 trials was judged at low risk of bias throughout. Their conclusion is carefully worded — antibiotics "may be effective in reducing the risk of pyelonephritis in pregnancy, but our confidence in the effect estimate is limited".

That is a real limitation, and it is also why the screening is not something to be annoyed about: the potential benefit is large, and the cost is a pot of urine.

One extra reason the culture matters: if group B streptococcus shows up in your urine, CKS says the midwife and obstetric team must be told, because antibiotics through a drip should then be offered during labour.

What it feels like — and what it is easy to confuse it with

The NHS lists the symptoms of a UTI as pain or a burning sensation when peeing, needing to pee more often than usual, needing to pee suddenly or more urgently than usual, cloudy pee, blood in your pee, tummy pain, a high temperature and tiredness. Tommy's adds that the urine may be dark or strongly smelling, and that the frequency is often worse at night.

Now the problem: needing to pee constantly is also just pregnancy. ACOG names it — "It can be easy to confuse UTI symptoms with common pregnancy symptoms, such as needing to urinate more often. A urine test should be done to confirm whether you have a UTI."

The features that point away from ordinary pregnancy frequency are pain or burning, urgency that is new, cloudy or bloody urine, and feeling unwell with it. If in doubt, the test settles it, which is the point.

What actually helps

A proper urine sample, before antibiotics start

CKS is specific that in pregnancy a midstream urine sample should be sent for culture and susceptibility testing — ideally a morning sample — and that dipstick testing should not be used to make the diagnosis. It also says to make sure the sample has been sent before antibiotic treatment begins, and to arrange a repeat sample after the course is finished "to ensure clearance of infection".

ACOG describes how to collect it cleanly: wipe front to back, hold the labia apart, pass a little urine into the toilet first and catch the rest, and avoid touching the inside of the cup or lid.

Antibiotics, chosen for pregnancy

ACOG: "UTIs in pregnancy are treated with antibiotics for 5 to 7 days. The antibiotics used to treat UTIs are safe and effective during pregnancy." CKS sets out the UK first and second choices — nitrofurantoin 100 mg modified-release twice daily for 7 days as first choice, avoided in the third trimester, with cefalexin 500 mg twice a day or amoxicillin 500 mg three times a day for 7 days as alternatives — with the final choice guided by what the culture grows.

Finish the course even once you feel better, which ACOG stresses, and expect most symptoms to settle within one to two days.

What does not help

This is where a lot of well-meaning advice falls down. CKS states plainly: "Do not recommend use of over-the-counter cranberry products or urine alkalinising agents (such as potassium citrate, sodium citrate, or sodium bicarbonate)." Those sachets are not a treatment for a UTI in pregnancy, and buying them instead of calling is the delay this page is trying to prevent.

What CKS does support alongside antibiotics is unglamorous: paracetamol for pain, and keeping your fluid intake up to avoid dehydration.

The short version

Stinging, urgency or cloudy urine in pregnancy earns a same-day appointment and a urine sample. Fever, shivering, back or side pain, vomiting or blood in your urine earns urgent care now. Antibiotics are safe, the course is short, and the reason everyone takes this seriously is what happens when it is left.