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Urinary Tract Infections and Pregnancy

Kate Dudek
May 7, 2019 . 3 min read

Urinary Tract Infections (UTIs) are common. The prevalence during pregnancy is estimated to be between 2 and 10%, which is similar to the prevalence in non-pregnant women. However, being pregnant does complicate things. For example, it is generally recommended to avoid antibiotics during the first trimester and, if they have to be taken, it is important to discuss with your doctor which ones provide the fewest risks to you and your unborn baby.

Most women will have acquired their UTI prior to falling pregnant and many remain asymptomatic. This is one reason why a urine sample is requested during pregnancy (doctors also use the urine sample to check for high sugars, which might be an early warning sign of gestational diabetes and proteins, which can be indicative of pre-eclampsia). Left untreated 30-40% of asymptomatic UTIs progress to kidney infection (pyelonephritis). Whilst UTIs pose minimal health risks to mother and baby themselves, pyelonephritis can be very unpleasant. It has an overall incidence rate of approximately 2% in pregnant women, compared to <1% of the general population. The most obvious symptoms are lumbar pain, vomiting, fever (>38°C) and tenderness in the area between the lower ribs and the spine. One in five women with pyelonephritis will also have septicaemia and most will require hospitalisation and IV antibiotics for at least 48 hours.

One of the most well-known forms of symptomatic UTI is cystitis. Common symptoms include cloudy urine, a frequent need to urinate and dysuria (painful urination). Symptomatic UTIs and pyelonephritis correlate with an increased risk of premature delivery and low birth weight. However, studies to date have failed to ascertain the overall contribution of the conditions to preterm births. A rare, but serious complication of UTIs in pregnant women is the risk of transmission to the baby during delivery.

Usually the treatment of choice for UTIs are antibiotics, however, as most have been shown to cross the placenta, care must be taken when choosing which one to prescribe. Streptomycin and tetracycline should definitely be avoided due to their teratogenic properties. Derivatives of penicillin, such as amoxicillin, and cephalosporins are generally considered to be amongst the safest options. As older drugs, their safety profiles and mechanisms of action are better understood than the newer drugs.

As with many things in life, when considering UTIs, prevention is certainly better than cure. Whilst the incidence of UTIs does not increase significantly during pregnancy, changes to the structure and composition of the urinary tract and increased urine retention, do provide optimal conditions for the growth of bacteria. Certain steps can help to minimise the risk of acquiring a UTI. Cranberry juice has long been recommended as an aide for avoiding and/or helping to manage UTIs. Studies show that it may prevent bacteria from attaching to the walls of the urinary tract. Alternative fruit juices are best avoided in favour of water. Remaining hydrated is important, so aim to drink between 1.5 and 2 litres of water a day. Maintain good hygiene by keeping the genital area clean. Avoiding strong soaps and wearing cotton underwear can also help to reduce the risk of UTIs. Finally, go to the toilet as soon as you feel the urge, as holding urine in your bladder for longer than necessary can increase the exposure to bacteria.


  • Matuszkiewicz-Rowińska, J, et al. “Urinary Tract Infections in Pregnancy: Old and New Unresolved Diagnostic and Therapeutic Problems.” Archives of Medical Science, vol. 11, no. 1, 16 Mar. 2015, pp. 67–77., doi:10.5114/aoms.2013.39202.
  • Norwitz, E R, and J A Greenberg. “Antibiotics in Pregnancy: Are They Safe?” Reviews in Obstetrics and Gynecology, vol. 2, no. 3, 2009, pp. 135–136.
  • Vasileiou, I, et al. “Current Clinical Status on the Preventive Effects of Cranberry Consumption against Urinary Tract Infections.” Nutrition Research, vol. 33, no. 8, Aug. 2013, pp. 595–607. doi:10.1016/j.nutres.2013.05.018.
  • Windham, L. “How to Prevent UTI During Pregnancy.” WikiHow,

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