The most common cause of wet panties in the fourth month of pregnancy is increased secretion, and there is also a situation caused by leakage of urine, because during pregnancy, affected by hormonal secretion, there will be increased secretion, this situation will lead to wet panties, but there is no odor. If there is a bad smell, it is considered to be caused by vaginitis, so a routine examination of the white belt is needed to determine the condition and treat it with medication in a timely manner. After pregnancy, as the fetus grows, the uterus will also increase in size, which will compress the nearby organs, resulting in a decrease in bladder volume, which will lead to urine leakage. If there is no painful urination, it is normal and does not require special treatment. If there is pain when you urinate, consider a urinary tract infection, you need to check the urinary routine, determine the condition and then use medication.