Please do not be overly alert when your baby stool is green, as long as the baby is eating well and there are no blood in her stool, it is pretty normal.
Green stool is a sign that your baby is taking in more foremilk (the first milk that come out of your breast that are high in lactose) than hindmilk. As a result of this, this increase the lactose in the baby body system causes the poo to turn green.
However if the symptoms last longer than 24 hours, visit your doctor. The can be also due the followin reasons:
Milk Powder brand or Formula
Medication side effect