Kidney Infection in Pregnancy

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Among the many changes that take place in the body during pregnancy is an increase in the risk of developing an infection of the urinary tract. The hormonal changes as well as the physical changes exerted by the enlarging uterus can lead to a slowdown of the passage of urine through the urinary tract and even to vesicouteral reflux, a condition in which urine in the bladder backs up, or refluxes, back into the ureters (the tubes that carry urine from the kidneys to the bladder). The hormone progesterone is responsible for changes in action of the smooth muscle walls of the ureters, and the weight of the uterus itself can lead to urinary retention. There is further an expansion of blood volume and increased load on the kidneys in pregnant women, resulting in increased urine output in the face of decreased mobility of the ureters. Finally, pregnant women tend to have higher urinary levels of glucose than nonpregnant women. All of these changes predispose to infection within the urinary tract.

As in nonpregnant women, urinary infections can occur in the urethra or bladder or may spread to the kidneys (pyelonephritis). The majority of infections come from existing bacteria in the vaginal and anal areas that spread upward (also termed retrograde) through the urinary system.

Fortunately, urinary infections in pregnancy are readily treatable. Even though pregnant women may be concerned about taking prescription medications, there are a number of antibiotics that are effective in treating kidney and urinary tract infections that are known to be safe for both mother and baby. Cephalexin, ampicillin, and nitrofurantoin are examples of antibiotics that may be used to treat lower urinary tract infections and cystitis in pregnant women. These medications are taken in pill or tablet form.

Medically Reviewed by a Doctor on 12/1/2014