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UTIs in Pregnancy: Why You’re More at Risk and What’s Actually Safe

By Olivia Wallis, founder of Onoma Health

A UTI in pregnancy is very common. Urinary tract infections affect around 8% of pregnancies, and they’re the most common infection pregnant women get. Pregnancy changes your hormones, your bladder and even the make-up of your urine in ways that make it easier for bacteria to take hold. The good news is that a UTI during pregnancy is usually easy to treat when it’s caught early.

If you’ve had recurrent UTIs before, pregnancy can feel worrying. This guide explains why pregnancy raises your risk, the symptoms to watch for in each trimester, how UTIs are treated in the UK, and what’s safe to take.

Key takeaways

  • Pregnancy hormones and your growing womb slow the flow of urine, giving bacteria more time to multiply.

  • A urine infection in pregnancy can have no symptoms at all, which is why your midwife tests your urine.

  • Always treat a UTI while pregnant. If it’s left untreated, it can spread to your kidneys.

  • Antibiotics chosen for your stage of pregnancy are the standard treatment.

  • Everyone is different. Speak to your midwife or GP before taking anything over the counter, including cystitis sachets, D-mannose and supplements such as Onoma Health’s Tract Tonic.

Why are UTIs more common in pregnancy? The science explained

Pregnancy makes UTIs more likely because urine flows more slowly and sits in the urinary tract for longer, which gives bacteria time to multiply. Most of these changes start in the first trimester, and the risk is highest between roughly weeks 6 and 24.

1. Progesterone relaxes your urinary tract

Progesterone rises sharply in pregnancy to relax smooth muscle so your womb can stretch. It also relaxes your ureters, the tubes that carry urine from your kidneys to your bladder. They widen and move urine along more slowly.

This widening starts from around week 6 and affects up to 90% of pregnant women, usually more on the right side. Doctors call it physiological hydronephrosis of pregnancy, and it’s normal.

2. Your growing womb presses on your bladder and ureters

As your baby grows, your womb presses on your bladder and ureters. Your bladder holds more and loses some tone, so a little urine is often left behind after you wee. Urine that sits still is an ideal place for bacteria to grow.

Urine can also flow back up towards the kidneys (vesicoureteral reflux). This is one reason infections in pregnancy more often become kidney infections.

3. Your urine changes

Pregnancy changes the chemistry of your urine. It tends to contain more glucose (sugar) and amino acids, and it becomes slightly less acidic. All of these help bacteria grow. This is also why gestational diabetes, which raises urine sugar further, increases UTI risk.

4. Your immune system adapts

Your immune system shifts during pregnancy so that it doesn’t react against your baby. This is essential, but it means your defences against some infections are slightly lowered.

5. Anatomy and everyday practicalities

Women already have a short urethra, about 3 to 4 cm long, which sits close to the anus. Most UTIs are caused by E. coli, a gut bacterium that can travel this short distance. Later in pregnancy, a growing bump can make it harder to wipe front to back and keep the area clean.

If you’ve had recurring UTIs before pregnancy, you’re more likely to get one while pregnant too, so it’s worth knowing the signs. Onoma Health’s guide Recurring UTIs? Here’s What Your Doctor Isn’t Telling You explains why some women keep getting them.

UTI symptoms in pregnancy

UTI symptoms in pregnancy are the same as at any other time, but they’re easier to miss because some overlap with normal pregnancy changes. Needing to wee more often is normal when you’re pregnant. Pain, burning or feeling unwell is not.

Symptoms of a UTI while pregnant include:

  • a burning or stinging feeling when you wee

  • an urgent need to wee, often passing only small amounts

  • cloudy, dark or strong-smelling urine

  • blood in your urine

  • pain or pressure low in your tummy, just above the pubic bone

  • new or worse leaking of urine

  • generally feeling unwell, tired or achy

UTI symptoms in early pregnancy

A UTI in early pregnancy is common because hormonal changes start around week 6. Frequent weeing is also an early pregnancy sign, so watch for burning, cloudy urine or a new ache low in your tummy.

UTI symptoms in the third trimester

In the third trimester, your baby’s head presses on your bladder. Frequent trips, leaking and pelvic pressure are normal, so UTI symptoms are harder to spot. Lower back ache and period-like tightenings can be mistaken for Braxton Hicks, but a UTI can trigger real contractions. Kidney infections are also more common later in pregnancy. If you’re unsure, ask your midwife to test your urine.

“Silent” infections: asymptomatic bacteriuria

Some women have bacteria in their urine with no symptoms. This is called asymptomatic bacteriuria and affects about 2 to 7% of pregnant women. In pregnancy it’s always treated because it can lead to a kidney infection. That’s why your urine is sent for testing at your antenatal appointments.

Warning signs of a kidney infection in pregnancy

Contact your GP, midwife or maternity triage urgently, or call NHS 111, if you have UTI symptoms and any of the following:

  • a high temperature (38°C or above), or shivering and chills

  • pain in your back or side, just below your ribs

  • feeling sick or being sick

  • tightenings, contractions or tummy pain

Call 999 if you become confused, drowsy, have trouble speaking or breathing, or notice mottled skin. These can be signs of sepsis. See the NHS guidance on UTIs and sepsis.

Can a UTI harm my baby? Possible complications

A bladder infection that’s treated promptly is very unlikely to harm your baby. The risks come mainly from infections that go untreated and spread upwards to the kidneys.

The main complications of an untreated UTI during pregnancy are:

  • Kidney infection (pyelonephritis). This is the most serious type of urine infection in pregnancy and usually needs hospital treatment with antibiotics through a drip.

  • Sepsis. In pregnancy, a kidney infection can progress quickly to sepsis, a life-threatening reaction to infection.

  • Preterm labour and birth. Infection and inflammation can trigger contractions or cause the waters to break early. Kidney infection in pregnancy has been linked to preterm delivery.

  • Low birth weight. Babies born to mothers with untreated urine infections are more likely to be smaller at birth.

  • Pre-eclampsia. Studies have linked UTIs in pregnancy to a higher risk of pre-eclampsia. One meta-analysis found about 1.6 times the odds, though this shows an association rather than proof of cause.

  • Anaemia in the mother.

That’s why even symptom-free infections are treated. Getting checked quickly protects you both.

UTI in pregnancy treatment: what to expect in the UK

A bladder infection in pregnancy is usually treated with a 7-day course of antibiotics chosen for your stage of pregnancy. A suspected kidney infection needs urgent assessment and may require different antibiotics.

What usually happens:

  1. A urine sample. You’ll be asked for a midstream urine sample, which is sent to the lab to identify the bacteria and which antibiotics will work.

  2. Antibiotics straight away if you have symptoms. Your GP or midwife won’t usually wait for the results. The choice may be changed once they come back.

  3. A 7-day course. In the UK, nitrofurantoin is usually the first choice. Cefalexin, or amoxicillin if the lab confirms it will work, are the main alternatives.

  4. A repeat test. Another urine sample is often checked about a week after you finish, to make sure the infection has gone.

The timing of some antibiotics matters. Nitrofurantoin is avoided near the end of pregnancy because of a small risk to the baby’s red blood cells. Trimethoprim is generally avoided in pregnancy, especially in the first trimester, because it affects folate. Your prescriber will take this into account.

For pain, paracetamol is usually the recommended painkiller in pregnancy. Avoid ibuprofen unless a doctor advises it. Keep sipping water too.

If you have a UTI caused by group B streptococcus (GBS), your care team will treat the infection and offer antibiotics during labour to protect your baby.

Are natural UTI remedies safe in pregnancy?

If you rely on remedies for recurrent UTIs, here’s what the evidence says once you’re pregnant. Everyone is different, and what suits you depends on your pregnancy, your medical history and any medicines you already take. So always check with your midwife or GP before starting anything new, especially over-the-counter products and supplements.

Is D-mannose safe in pregnancy?

D-mannose is a natural sugar that may stop E. coli sticking to the bladder wall so it’s flushed out when you wee. Research on D-mannose in pregnancy is limited, because no controlled trials have looked at pregnant women. That applies to branded D-mannose supplements too. Even outside pregnancy, a Cochrane review found the evidence is still developing.

NICE says women who are not pregnant may wish to try D-mannose to help prevent recurrent UTIs, and its guidance doesn’t cover pregnancy. Everyone is different, so if you’re pregnant or trying to conceive, speak to your midwife or GP first. Take your current medicines and pregnancy history along so they can advise what’s right for you. D-mannose should never replace antibiotics for an active infection.

Where does Tract Tonic fit?

Tract Tonic is Onoma Health’s daily drink for urinary tract and bladder wellness, created for women who are tired of dealing with recurrent UTIs. It brings together D-mannose and cranberry extract with fennel seed extract, vitamin C, vitamins B6 and D3, magnesium, calcium, potassium citrate and the prebiotic fibre inulin. You simply mix one serving with water each day.

Tract Tonic is made with natural ingredients, but natural doesn’t always mean right for every pregnancy. Some of its ingredients haven’t been well studied in pregnancy or breastfeeding. So please speak to your midwife or GP before using Tract Tonic while you’re pregnant or breastfeeding. Show them the full ingredient list from their website so they can give you personal advice.

Is cranberry juice safe during pregnancy?

Cranberry juice is generally considered safe during pregnancy. A Norwegian study of more than 68,000 pregnancies found no link between cranberry use and problems such as preterm birth, low birth weight or birth defects. But it can’t treat a UTI, and shop-bought juices may do more harm than good. Many are high in added sugar, which matters if you’re at risk of gestational diabetes. High blood sugar can also make thrush (a Candida yeast infection) more likely, and sugary diets may upset your gut microbiome.

Is nitrofurantoin safe in pregnancy?

Yes, for most of pregnancy. Short courses of nitrofurantoin are unlikely to harm your baby, and it’s the usual first choice in the UK. It’s avoided close to your due date, so your prescriber may choose a different antibiotic in late pregnancy.

How to prevent a UTI in pregnancy: practical tips

You can’t change your hormones, but simple daily habits can lower your risk of a UTI during pregnancy. Most are recommended by NHS maternity teams. For the habits that helped Olivia, founder of Onoma Health, read UTI Prevention: My Personal Journey to Becoming UTI-Free.

  • Drink enough fluids. Aim for pale straw-coloured urine. Water flushes bacteria out before they can settle.

  • Don’t hold it in. Go when you feel the urge.

  • Empty your bladder fully. Lean forward slightly on the toilet. Try “double voiding”: wait a moment after you finish, then try again.

  • Wee after sex to flush away bacteria pushed towards the urethra.

  • Wipe from front to back. As your bump grows, wiping from behind may be easier.

  • Choose loose cotton underwear to keep the area dry.

  • Skip perfumed soaps and washes. They can irritate the urethra. Plain water is enough.

  • Keep your antenatal appointments. Routine urine checks catch silent infections early.

Probiotics are generally considered safe in pregnancy. Many women also like to add a daily supplement to their bladder health routine. If that’s you, ask your midwife or GP whether something like Tract Tonic is suitable for your pregnancy before you start.

Recurrent UTIs and planning a pregnancy

If you get recurrent UTIs, talk to your GP before you try to conceive, and tell your midwife at your booking appointment. Under NICE guidance, pregnant women with recurrent UTIs should be referred to a specialist. A specialist may consider a low-dose preventive antibiotic during pregnancy. It’s also a good moment to review any supplements you take, including Tract Tonic, so your GP can advise what to continue. To understand what drives repeat infections, read Recurring UTIs? Here’s What Your Doctor Isn’t Telling You.

The bottom line

A UTI in pregnancy is common and very treatable. It just shouldn’t be ignored. Know the symptoms, keep up with your antenatal urine checks, and contact your GP or midwife as soon as something feels wrong. Prompt treatment is the best way to protect you and your baby.

Whether you’re planning a pregnancy, expecting, or looking after a new baby, Onoma Health exists to help you break the cycle of recurring UTIs. Discover Tract Tonic and their expert guides at onoma.health. As with anything in pregnancy, check with your midwife or GP before starting a new supplement.

Frequently asked questions about UTIs in pregnancy

Can a UTI harm my baby?

A UTI that’s treated quickly is very unlikely to harm your baby. Untreated infections can spread to the kidneys and raise the risk of preterm birth and low birth weight. That’s why every UTI in pregnancy is treated, even without symptoms.

Is a UTI a sign of early pregnancy?

No. A UTI isn’t a sign of pregnancy, but needing to wee more often is an early pregnancy symptom, so the two are easily confused. UTIs are also more common from around week 6, when pregnancy hormones start to affect the urinary tract. If you’re unsure, take a pregnancy test and see your GP about any burning or pain.

Is D-mannose safe in pregnancy?

D-mannose, including branded supplements, hasn’t been tested in controlled trials in pregnant women, and NICE’s suggestion to try it applies to women who aren’t pregnant. Everyone is different, so speak to your midwife or GP before taking it.

Is cranberry juice safe during pregnancy?

Cranberry juice is generally considered safe in pregnancy, and a large study found no link with pregnancy complications. However, it can’t treat an active UTI infection, and many juices contain a lot of sugar.

Can I use cystitis sachets while pregnant?

Check with your GP or pharmacist first. Manufacturers advise pregnant women to get medical advice before using cystitis sachets. They ease symptoms rather than clearing an active infection, and they can make nitrofurantoin less effective.

Can I take Tract Tonic while pregnant?

Speak to your midwife or GP before you start. Tract Tonic is made with natural ingredients, but some, including D-mannose and fennel seed extract, haven’t been well studied in pregnancy. Take the ingredient list and details of any medicines you take so they can advise you personally.

Will a UTI go away on its own when pregnant?

Don’t wait to find out. Outside pregnancy, a mild UTI sometimes clears without antibiotics. In pregnancy, it should always be treated to stop it spreading to your kidneys.

Are UTIs more common in the third trimester?

Kidney infections are more common in the second and third trimesters. Bladder symptoms are also harder to tell apart from normal late-pregnancy pressure. Ask for a urine test if you notice burning, cloudy urine or new back pain.

Research and sources

This article draws on UK guidance, systematic reviews and peer-reviewed research. It’s for general information and isn’t a substitute for advice from your GP, midwife or pharmacist.

UK national guidance

European medicines guidance

NHS clinical guidance

Systematic reviews and peer-reviewed research

Medicine information and clinical references

Patient information