What are the benefits of routinely screening for bacteria in the urine of pregnant women?

Photo of a pregnant woman at the hospital
PantherMedia / Iakov Filimonov

It’s not clear whether it’s a good idea to routinely screen for in the urine of pregnant women (bacteriuria ). It’s also not possible to say whether should be used if high levels of are detected in the urine but there are no noticeable urinary tract problems.

Routine tests are carried out during pregnancy to see whether the baby is developing normally and the mother is healthy. Screening tests in pregnancy include ultrasound scans and blood tests, as well as urine tests. In Germany, special guidelines (“Mutterschafts-Richtlinien”) specify what is to be tested in pregnancy, and what sorts of tests are used.

Urine tests during pregnancy

These guidelines specify that pregnant women should have routine urine tests. The urine is tested for proteins, sugar and bacteria. Routine testing for is also referred to as bacteriuria . If high levels of are detected in the urine, additional testing is done to confirm the results.

Laboratory results show that about 2 to 15 out of 100 pregnant women have above-average levels of in their urine, but the aren’t causing any symptoms. This is called “asymptomatic bacteriuria.”

Urinary tract infections and possible consequences

Having in your urine doesn’t often cause any problems. The usually just go away after a while. But women who have in their urine might go on to develop a urinary tract (UTI) such as cystitis.

Hormonal and physical changes make pregnant women more susceptible to urinary tract infections. These arise if infect the urethra (the tube that urine flows out of) and bladder. If the germs move upwards, they may also infect the ureters or kidneys.

Typical signs of a lower urinary tract include the following:

  • Increased urge to urinate
  • Painful urination

The following symptoms may also appear if the ureters or the renal pelvis are infected:

  • Fever
  • Pain around the kidneys (flank pain)
  • In some cases, nausea and vomiting

If you have at least one of these symptoms, it is important to see your doctor.

In rare cases, untreated urinary tract infections during pregnancy may lead to serious problems such as septicemia (blood poisoning). The presence of in urine is also associated with a higher risk of premature birth and low birth weight.

Pregnant women who have in their urine are usually given to prevent possible complications – even if they don’t have any symptoms.

Research in this area

Researchers from the Institute for Quality and Efficiency in Health Care (IQWiG, Germany) wanted to find out whether routine testing for in urine during pregnancy actually has any benefits for the mother or the child. But the IQWiG researchers didn’t find any suitable studies on the benefits of these tests. So instead, they looked into the advantages and disadvantages of in the treatment of asymptomatic bacteriuria: Do the help to prevent complications in the mother and child if are found in urine but there are no symptoms of a urinary tract ? They found three suitable studies on this topic. The women who participated in the studies either took , a placebo medication (fake treatment) or didn’t have any treatment.

Not clear whether testing for bacteria in urine during pregnancy has benefits

But the researchers weren’t able to draw any conclusions about whether taking to treat asymptomatic bacteriuria has any advantages or disadvantages. The studies didn’t provide important information about the study participants and the possible side effects of the . Also, the medicines used in the studies are no longer used nowadays. The studies were done in the 1960s, and their results can’t be directly applied to the current health care situation for pregnant women.

So it’s still not clear whether it makes sense to routinely screen for in urine during pregnancy. It’s also not clear whether pregnant women should take if are found in their urine but they don’t have any symptoms.

Institute for Quality and Efficiency in Health Care (IQWiG, Germany). Screening for asymptomatic bacteriuria within the framework of the German maternity guidelines, under special consideration of test methods: Final report; Commission S13-02. February 19, 2015 (IQWiG reports; Volume 279).

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Updated on March 22, 2018
Next planned update: 2022


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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