pregnant women with utis have a higher risk of kidney infections.during pregnancy, high progesterone (a hormone) levels decreased muscle tone of the ureters and bladder. decreased muscle tone leads to a greater likelihood of reflux, where urine flows back up the ureters and toward the kidneys. if bacteria are present, pregnant women have a 25-40% risk of a kidney infection. thus treatment is recommended if urine testing shows signs of an infection—even in the absence of symptoms. cephalexin or nitrofurantoin are typically used because those medications are generally considered safe in pregnancy. a kidney infection during pregnancy may result in premature birth or pre-eclampsia (a state of high blood pressure, kidney dysfunction, or seizures).