Yellow, mushy bowel movements are perfectly normal for breast-fed babies. Still, there are many shades of normal when it comes to baby poop. Here's a color-by-color guide for newborns:

• Black or dark green. After birth, a baby's first bowel movements are black and tarry. This type of baby poop is known as meconium.
• Yellow-green. As the baby begins digesting breast milk, meconium is replaced with yellow-green bowel movements.
• Yellow. Breast-fed newborns usually have seedy, loose bowel movements that look like light mustard.
• Yellow or tan. If you feed your newborn formula, his or her bowel movements might become yellow or tan with hints of green. They will be slightly more firm than breast-fed bowel movements, but no firmer than peanut butter.

Once your baby begins eating solid food, his or her bowel movements might contain a wide variety of colors.

If you're concerned about the color or consistency of your baby's bowel movements, contact your baby's doctor. This is especially important if your baby's bowel movements are:

• Still black several days after birth
• Red or bloody
• White
• Suddenly more frequent and unusually watery
• Less frequent than what is normal for your baby or consistently hard, dry and difficult to pass

When you contact the doctor, be prepared to describe your baby's bowel movements, including color, consistency, volume and frequency. The more details you provide, the better the doctor will be able to help you determine what's normal for your baby — and when treatment might be needed.