Urinary Tract infections




Rebecca J. Baer, MPH, Nichole Nidey, MS, Gretchen Bandoli, PhD, Brittany D. Chambers, PhD, Christina D. Chambers, PhD, Sky Feuer, PhD, Deborah Karasek, PhD, Scott P. Oltman, MS, Larry Rand, MD, Kelli K. Ryckman, PhD, and Laura L. Jelliffe-Pawlowski, PhD 

Urinary tract infections (UTIs) are frequent during pregnancy, affecting as many as 8% of pregnant women.  Physical changes during pregnancy such as increased bladder volume and decreased bladder tone, as well as a change in the vaginal flora increase risk of a UTI. Infection often begins as asymptomatic bacteriuria, which progresses to a lower tract infection (acute cystitis) in 30% of patients and can lead to upper tract infection (acute pyelonephritis) in up to 50% of patients. Current guidelines recommend testing for bacteriuria during early pregnancy.  Treatment with a pregnancy-appropriate antibiotic is recommended, regardless of symptoms.  

UTIs have been associated with preterm birth (PTB) (<37 weeks' gestation) in some studies. However, these findings have not been consistently replicated. The suggested pathophysiology of the relationship is that the bacteria ascends to the uterus, causing an inflammatory reaction, which leads to uterine contractions and chorioamniotic membrane degradation.  An alternative hypothesis is that a significant maternal infection from a UTI releases prostaglandins into the maternal circulation. These prostaglandins then stimulate cervical ripening and uterine contractions. 


A urinary tract infection (UTI) is an infection of the urinary system. UTIs are the most common bacterial infection that women develop during pregnancy. They can occur in different parts of the urinary tract, including the bladder (cystitis), urethra (urethritis) or kidneys (pyelonephritis). Sometimes when a UTI develops and bacteria are detected in the urinary tract, you may not have any symptoms of an infection. This is known as asymptomatic bacteriuria. 

Common symptoms of a UTI during pregnancy are similar to those that you might experience at any other time, and include: 

  • a burning sensation when you pass urine 
  • feeling the urge to urinate more often than usual 
  • urinating before you reach the toilet (‘leaking’ or incontinence) 
  • feeling like your bladder is full, even after you have urinated 
  • urine that looks cloudy, bloody or is very smelly 
  • pain above the pubic bone 
  • fever

Sometimes the first sign of an infection is a faint prickly sensation when you pass urine. If the infection is more advanced and has moved up to the kidneys, you may also experience fever with a particularly high temperature, back pain, and vomiting. 

What are the common causes of UTIs? 

Your urinary tract is normally free of bacteria. If bacteria enter the tract and multiply, they can cause a UTI. There are several factors that increase the risk of developing an infection: 

  • Infection with common bacteria in your gut, usually from faeces (poo) can contaminate your urinary tract 
  • Being sexually active increases, the risk of bacteria moving around the genital area and entering the urinary tract 
  • If you have weak pelvic floor muscles your bladder might not empty completely, which can lead to an infection 
  • Women with diabetes are at increased risk of developing a UTI since the sugar in their urine may cause bacteria to multiply

Are UTIs a risk during pregnancy? 

During pregnancy, many changes occur in your body that increase your risk of developing a UTI, including changes to the make-up of your urine and immune system. As your baby grows, there is also an increase in the pressure on your bladder, which can reduce the flow of your urine and lead to an infection. 

UTIs can affect women whether they are pregnant or not. However, pregnant women are more likely to develop repeated or more severe infections. Up to 1 in 10 pregnant women will have a UTI but not have any symptoms at all. 

Is there a risk to my baby? 

Having a UTI during pregnancy can increase your risk of developing high blood pressure, and your baby may be born early and smaller than usual. For this reason, even if you don’t have any symptoms, it is important to treat a UTI as soon as possible. 

How are UTIs diagnosed? 

UTIs are diagnosed by taking a urine sample which is checked in a laboratory for bacteria. Your doctor may also perform a physical examination if they think you have an infection. 

All pregnant women are offered a urine test, usually at their first antenatal visit or soon after.  

You may need to repeat the urine test if you have a history of UTIs; have symptoms of a UTI; have a contaminated sample or if your doctor thinks you are at high risk of developing a UTI. If you have frequent UTIs, you may also need additional tests such as an ultrasound of your kidneys. 

How are UTIs treated during pregnancy? 

When you have a UTI, it is important to drink plenty of water to flush out the urinary tract. UTIs are treated with antibiotics that are safe in pregnancy. Your doctor will select the right antibiotic, based on your infection and the type of bacteria found in your urine sample. 


UTIs can be safely treated with antibiotics during pregnancy. Urinary tract infections are most commonly treated by antibiotics. Doctors usually prescribe a 7 day course of antibiotics that is safe for you and the baby. Call your doctor if you have fever, chills, lower stomach pains, nausea, vomiting, contractions, or if after taking medicine for three days, you still have a burning feeling when you urinate. 

Can I prevent UTIs? 

You can lower your risk of developing a UTI during pregnancy by:

  • drinking plenty of fluids, especially water 
  • quickly treating any vaginal infection that may occur, including thrush or a sexually transmitted infection 
  • avoiding becoming constipated 
  • Some women have also found the following tips helpful: 
  • urinate immediately after sex 
  • don’t delay going to the toilet — go as soon as you feel the need 
  • wipe from the front to the back after going to the toilet 
  • wear cotton underwear

Useful Links 

The Australian Preterm Birth Prevention Alliance (APBPA) 


Pregnancy, Birth and Baby 


Health Direct Australia 


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Disclaimer: This publication by Miracle Babies Foundation is intended solely for general education and assistance and it is it is not medical advice or a healthcare recommendation. It should not be used for the purpose of medical diagnosis or treatment for any individual condition. This publication has been developed by our Parent Advisory Team (all who are parents of premature and sick babies) and has been reviewed and approved by a Clinical Advisory Team. This publication is not a substitute for professional medical advice. Miracle Babies Foundation recommends that professional medical advice and services be sought out from a qualified healthcare provider familiar with your personal circumstances.To the extent permitted by law, Miracle Babies Foundation excludes and disclaims any liability of any kind (directly or indirectly arising) to any reader of this publication who acts or does not act in reliance wholly or partly on the content of this general publication. If you would like to provide any feedback on the information please email [email protected].