One month old baby usually passes frequent normal consistency stools and it is quite normal for this age and as age advances the frequency will come down and they will pass stools once in 2 to 3 days and this also normal. Because of frequent passage of stool and frequent cleaning of that area with ware this rash
will develop. Gently clean the area, apply zinc oxide
containing creams and frequently change the diapers and allow the area to get dry.
Dr E Venkata Ramana