Blood down there in a newborn baby girl is usually seen on the diaper. This is important to identify if it is from vaginal bleeding, or if there is bloody urine or blood in the stool. Generally little girls can have pseudo-menstruation about a week after birth due to the mother’s progesterone and estrogen levels, and vaginal bleeding can be noticed at this time. However, if the newborn has blood in the urine and sometimes the diaper is red, you can use a sterile urine bag to take the newborn’s urine for routine examination. If the urine color is light red or dark red throughout, or even invisible, but there is blood in the urine under the microscope, then the red color may be from the urinary tract. Blood in the stool is usually better distinguished, for example, if there is a small amount of blood in the stool so that it can be distinguished.