Urinary tract infections and pregnancy

Urinary tract infections are common during pregnancy and call for particular attention. Hormonal and physical changes make pregnant women more susceptible to these infections which, if left untreated, can lead to serious complications.

What is a urinary tract infection?

A urinary tract infection (UTI) is a bacterial infection that can affect any part of the urinary system: the bladder (cystitis), the urethra (urethritis) and/or the kidneys (pyelonephritis). During pregnancy, UTIs are more common and potentially more dangerous for both the mother and the baby.

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Why are pregnant women more at risk?

Several factors increase the risk of developing a UTI during pregnancy:

• Hormonal changes: Progesterone relaxes the muscles of the urethra and the bladder; the urinary meatus is more distended, which opens the door to microbes spreading from the outside. This relaxation is also behind a possible reflux of urine from the bladder back toward the kidneys.‍
• An altered urinary pH: The environment becomes more favourable to bacteria.‍
• A weakened immune system: The natural, physiological dip in the immune system, especially in the third trimester, can encourage bacteria to appear in the urinary tract.
• The bladder shifting: As the uterus moves upward, the bladder can end up more in the abdominal cavity than inside the pelvis, which can interfere with its functions and cause pain when passing urine. ‍
• Pressure on the bladder: The expanding uterus presses on the bladder, slowing down circulation and the flow of the waste to be eliminated (urine).
• Incomplete bladder emptying: Progesterone's relaxing effect on the muscles also causes the bladder to stretch more, making it harder to empty it completely when passing urine.
  

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Types of urinary tract infections

Between 2 and 15% of pregnant women will have a urinary tract infection during their pregnancy without knowing it, since they will have no particular symptoms. Unfortunately, this situation can develop into a full-blown infection, either cystitis or pyelonephritis.

Asymptomatic bacteriuria: This infection affects 5 to 10% of pregnancies, with bacteria present but no symptoms. It needs to be treated, even in the absence of symptoms, because it can progress to a symptomatic infection.

Acute cystitis: A more common infection during pregnancy, affecting the bladder, with symptoms. When properly treated, it rarely progresses.

Pyelonephritis: This is the most serious form of infection, since it affects the kidneys. It occurs in 1 to 2% of pregnancies. It can cause preterm labour and often requires hospitalization.

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Symptoms

When there are symptoms, they can come on suddenly or gradually, alone or several at once.

• A burning sensation and/or pain when passing urine
• A more frequent and urgent need to urinate, without being able to (or only a few drops)
• Passing urine more often
• Urine that is often darker, cloudy or murky
• A feeling of pressure in the lower abdomen
• Sometimes, blood in the urine
• Sometimes, a strong smell coming from the urine

When a urinary tract infection is not detected and treated in time, it can move up to the upper urinary tract and cause a kidney infection (pyelonephritis) in 20 to 40% of cases. On top of the fever, the pain of pyelonephritis is very intense and located more specifically in the lower back. Chills, nausea and vomiting can also be part of the picture with this more specific infection.

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IMPORTANT: Any fever during pregnancy calls for an immediate consultation.

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Diagnosis

Urine analysis and urine culture are an integral part of the screening tests recommended in the first trimester of pregnancy for every pregnant woman.

Some women known to have a significant history of UTIs, or who have health conditions such as diabetes, may be offered closer monitoring in this respect.

If pyelonephritis is suspected, additional tests may be ordered, such as blood tests and/or a kidney ultrasound.

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Treatment

Several antibiotics can be prescribed safely during pregnancy.

IMPORTANT: Always finish the full course of treatment.

In the case of pyelonephritis, hospitalization is often necessary, in order to receive intravenous antibiotics, monitor the baby's condition and make sure hydration is maintained.

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Possible complications

If left untreated, a UTI can cause:

In the mother:

• Pyelonephritis Sepsis (blood infection)
• Anemia
• Preterm labour
• Premature rupture of the membranes
  

In the baby:

• Low birth weight
• In rare cases, fetal death

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Prevention

Hygiene measures and good lifestyle habits can help reduce the chances of getting a urinary tract infection:

• Hydration: Drink plenty of water (8-10 glasses a day) Water dilutes the urine and helps flush out bacteria
• Hygiene: Wipe from front to back
• Urinate before and after sexual intercourse
• Avoid irritating products (vaginal douches, scented soaps)
• Wear cotton underwear
• Urinary habits: Do not hold in your urine
• Empty your bladder completely
• Urinate regularly (every 2-3 hours)
  

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