HomeHealth articlespregnancyWhy Are Urinary Tract Infections Common in Pregnancy?

Urinary Tract Infection in Pregnancy - Causes, Symptoms, Treatment and Prevention

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A urinary tract infection (UTI) is common in pregnant women. It refers to the infection of the kidneys, ureters, bladders, or urethra of the urinary system.

Written by

Dr. Sri Ramya M

Medically reviewed by

Dr. Sanap Sneha Umrao

Published At May 5, 2023
Reviewed AtSeptember 14, 2023


A urinary tract infection affects the kidneys, ureters (tubes that transport urine from the kidneys to the bladder), bladder, or urethra (a short tube that transports urine from the bladder to the outside of the body) of the urinary system. It occurs when bacteria from outside enter the urethra to cause an infection. The urinary tract infections are more common in women compared to men, because the anatomy of female genitalia makes it easier for the bacteria from the vaginal or rectal areas to enter the urinary tract and cause infection.

Why Are Urinary Tract Infections Common in Pregnant Women?

The urinary tract infections are common in pregnant women due to the immunocompromised state and various other causes.

The urinary tract infection can be due to one of the following causes:

  • The growing fetus (the developing baby) puts pressure on the bladder and urinary tract and causes urine leaks, which may trap bacteria resulting in an infection.

  • An increase in progesterone hormone during pregnancy may cause smooth muscle relaxation resulting in dilation and urinary stasis, and also increases vesicoureteral reflux (a condition in which the urine travels back from the bladder to the kidneys). Ureteral dilation that occurs due to the compression of the ureters by the gravid uterus, and dilation of the ureters and renal calyces (chambers inside the kidney) due to smooth muscle relaxation effect by the progesterone hormone can predispose a woman to urinary tract infections. These physiological changes decrease the bladder capacity resulting in frequent urination, thereby increasing the risk of urinary tract infections during pregnancy.

The organisms that cause urinary tract infections are the same in pregnant and non-pregnant women. However, the physiological and immunological changes in pregnancy increases the risk of urinary tract infections. Also, urinary catheterization during labor, and changes in bladder sensitivity and bladder overdistention during the postpartum period may increase the chances of urinary tract infections.

What Are the Causes of a Urinary Tract Infection in Pregnant Women?

The causative organisms are the same in a pregnant and a nonpregnant woman. E. coli (Escherichia coli) is the common organism that causes urinary tract infection. Other bacteria that cause urinary tract infections include Streptococcus, Proteus, Klebsiella pneumoniae, Staphylococcus, and Enterococcus species.

  • Escherichia coli in the rectal area enters the urethra if an individual does not wipe the feces from front to back. Also, during sexual activities the bacteria near the vagina enter the urethra.

  • Group B Streptococcus is common in the colon and rectal region, and can enter the urethra to cause urinary tract infection. It can also be passed to the newborns during labor resulting in infection in the newborns.

What Are the Signs and Symptoms of a Urinary Tract Infection During Pregnancy?

Some women may remain asymptomatic and are referred to as asymptomatic bacteriuria. A urinary tract infection causes the following symptoms in a pregnant woman.

  • Pain or a burning sensation during urination.

  • Increased frequency and urge to urinate.

  • Suprapubic pain and tenderness.

Other symptoms such as malaise (discomfort), anorexia (an abnormal loss of appetite), nausea, and vomiting may be present. The following symptoms are present in case of pyelonephritis (inflammation of the kidney due to urinary tract infection that travels from the urethra or bladder to the kidneys).

  • Fever.

  • Chills.

  • Flank pain.

Is a Urinary Tract Infection During Pregnancy Dangerous?

Any infection during pregnancy can cause complications to the mother and fetus, and may increase the risk of preterm labor. Pyelonephritis is a serious complication caused by a urinary tract infection. The infection from the urethra or bladder travels up to reach the kidneys and causes inflammation and infection.

Pyelonephritis may cause permanent renal damage. Urinary tract infections also cause complications such as, preterm labor, acute respiratory distress syndrome, anemia, and severe and long-term infection in the pregnant mother. Severe infection leads to sepsis resulting in complications such as tachycardia (rapid heartbeat), hypotension, and reduced urine output.

How Is a Urinary Tract Infection in Pregnant Women Diagnosed?

Due to the risk of urinary tract infection in pregnancy, all pregnant women are screened for asymptomatic bacteriuria at the first prenatal visit. A clean catch urine culture is performed to diagnose the presence of bacteriuria and the type of bacteria causing the infection.

Other laboratory tests include urinalysis, complete blood count, serum creatinine, and electrolytes. GBS cultures (Group B Streptococcus) from a vaginal and rectum swab are performed, if severe complications are present. Renal ultrasound is required to determine the presence of a renal abscess (a sac filled with pus in the kidney tissue).

How Is a Urinary Tract Infection in Pregnant Women Treated?

Asymptomatic bacteriuria (ASB) and cystitis caused by urinary tract infections require antibiotic therapy. Antibiotics are decided based on the organisms detected in the urine culture tests. Antibiotics such as Amoxicillin, Cephalosporins, Ampicillin, and Nitrofurantoin are recommended for pregnant women, for a period of three to seven days. An intravenous antibiotic therapy is recommended during labor, for patients infected with GBS to prevent the onset of sepsis. Also, two to four weeks after the completion of the treatment, a urine culture test is performed to rule out reinfection.

How to Prevent Urinary Tract Infections During Pregnancy?

The following instructions can help prevent a urinary tract infection in a pregnant woman:

  • It is essential to drink at least eight glasses of water a day to stay hydrated.

  • After passing stools, it should be wiped from front to back.

  • A water-based lubricant should be used during sexual activities.

  • Urinate frequently to empty the bladder.

  • Strong scented soaps or other products that irritate the vulva should not be used.

  • The genital areas should be washed before and after sex.

  • Avoid wearing pants and inners that are tight, and wear comfortable cotton innerwears.

  • Avoid alcohol, caffeinated drinks, spicy foods, and citrus juices as they irritate the bladder.


A urinary infection is common in women, but pregnant women are at a higher risk due the immunological and physiological changes during pregnancy. As pregnant women are relatively immunocompromised, the chances of infection are higher. A urinary tract infection can cause serious complications in pregnant women. Therefore, following the precautionary measures can help prevent the infection. All pregnant women are screened for asymptomatic bacteriuria in the first prenatal visit because many women with urinary tract infections remain asymptomatic. Early diagnosis and proper intervention can help prevent the risk of serious complications caused by a urinary tract infection.

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Dr. Sanap Sneha Umrao
Dr. Sanap Sneha Umrao

Obstetrics and Gynecology


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