Women, especially pregnant women, are prone to urethritis, cystitis, pyelonephritis, and other diseases due to their physiology, collectively known as urinary tract infections. Surveys have shown that the incidence of urinary tract infections in pregnant women is as high as 11% and can occur during all periods of pregnancy. Some of them are often neglected because they only present with back pain and no other discomfort. In fact, early diagnosis and timely treatment of urinary tract infections can cure most of them without causing too much damage. After pregnancy, the ureter grows and thickens, and with the influence of progesterone, the smooth muscle of the wall relaxes and peristalsis decreases and weakens. In late pregnancy, the enlarged uterus compresses the bladder and ureter, causing poor urinary flow and urinary retention. The retained urine not only irritates the mucous membrane of the urethra, but also tends to breed bacteria. The increase of nutrients such as glucose and amino acids in urine after pregnancy also provides favorable conditions for bacterial reproduction. How to prevent urinary tract infection? The main thing is to increase nutrition, improve physical fitness, and abstain from intercourse, especially during the first three months of pregnancy and the three months before delivery. Even if there is occasional intercourse, both men and women should wash their sexual organs and vulva, and the woman should also urinate once after intercourse to flush the urethra with urine and reduce the chances of urinary tract infection. Pregnant women should insist on washing their vulva daily and changing their underwear regularly; they should go to the hospital for regular urine tests, even if they do not have symptoms of urinary tract infection, they should be checked once a month in order to detect changes in urine in time. Pregnant women with urinary tract infection should drink more water so that the daily urine volume reaches more than 2000 ml. Treatment should take into account both the effective control of urinary tract infection and the safety of the fetus, because many antibiotics can affect the fetus through the placenta, such as sulfonamides can lead to hemolytic anemia, teratogenic, and in the last two of pregnancy, use can also cause jaundice in the fetus.