Babies' bowel movements or stools vary considerably in color, consistency and frequency. What is normal for your baby may not be normal for someone else's.

During the first 2 or 3 days, the stools will be very dark, green or even black, and sticky. This is meconium; your baby is eliminating the residue remaining in his intestines from before he was born. Colostrum, the mother’s milk during the first few days, has this cleaning function. Then during the first year the frequency and consistency of defecation will vary depending on what the baby is fed. You will gradually learn to recognize your child’s normal feces. See your doctor if his stools are red or black because this may indicate blood.

During breastfeeding, stools may range from mustard yellow to yellow-green. They are liquid or semi-liquid and smell of sour milk.

During the first 6 weeks, newborns may have up to 10 bowel movements a day. After that, most babies have 2 to 5 plentiful movements a day as long as they’re breastfed; others have only one movement a week. If your baby is defecating infrequently but the stools remain soft, there should be no problem.

If your baby’s stools suddenly change from soft to liquid, there may be a transient trouble. Some medications can cause a change. For example, an iron supplement may cause black or dark brown stools.

If your baby is healthy and developing normally, don’t worry about his stools.

Stool frequency and consistency similar to that of the breastfed infant.

Reference:
Doré, Nicole; Le Hénaff, Danielle. From Tiny Tot to Toddler, Practical Guide for Parents from Pregnancy to Age Two. Québec, Institut national de santé publique du Québec, 2008. Page 172-173.