Itchy bottom in the fifth month of pregnancy is mostly caused by vaginitis during pregnancy. The changes in sex hormone levels during pregnancy and the weakened resistance of pregnant women can easily lead to increased vaginal discharge, which can easily lead to vaginitis during pregnancy if not properly taken care of. The most common clinical manifestation of vaginitis during pregnancy is vulvar itching. If you experience vulvar itching and increased discharge, you should not use medication blindly because there are restrictions on the use of medication during pregnancy. It is recommended to go to the hospital for a leucorrhoea examination to clarify the type of pathogenic bacteria of the infection, and according to the different types of vaginitis, choose the appropriate medication for vaginal application during pregnancy, and be careful not to place the medication too deeply when using it, so as not to stimulate the uterus too much and cause miscarriage.