-Untreated bacteriuria has been associated with an increased risk of preterm birth, low birth weight, and perinatal mortality

-Most common pathogen: E.Coli

-Screen all pregnant women for asymptomatic bacteriuria at 12-16 weeks or the first prenatal visit with the culture of a urine specimen.

-Treat asymptomatic bacteriuria and cystitis: Nitrofurantoin (avoid use during the first trimester and at term), Amoxicillin, amoxicillin-clavulanate, cephalexin, cefpodoxime, Fosfomycin. -Trimethoprim-sulfamethoxazole: Avoid during the first trimester and at term; a folic acid antagonist, caused abnormal embryo development in animal studies.

-Avoid sulfonamides in the last days before delivery because they can displace bilirubin from plasma binding sites in the newborn, increasing the risk for kernicterus.

-Avoid aminoglycosides; they can cause ototoxicity.

-Do not use tetracyclines and fluoroquinolones

Pyelonephritis: presence of flank pain, nausea, vomiting, fever, costovertebral angle tenderness.

Treatment of pyelonephritis: Hospitalization with intravenous antibiotics and later oral antibiotics (ceftriaxone, cephalexin, cefazolin, ampicillin plus gentamicin)

Safe antibiotics throughout pregnancy: Penicillins, Cephalosporins, Aztreonam and Fosfomycin.