A: Nalo, infants can make a surprising variety of facial expressions and sounds. It's normal for infants to strain, grunt, and turn pink in the face when they have a bowel movement.

However, the traces of blood in your baby's stool should be checked out by your doctor. Some possible causes are:

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• Constipation: What is the consistency of your baby's stools? Breastfed babies tend to have runny, yellowish stools. Formula-fed babies tend to have more firm and brownish stools, but they should still be soft—at least as soft as peanut butter. If your baby's stools are hard like pebbles, she could be constipated. Are you just giving your newborn formula and/or breastmilk, or are you also putting cereal in the bottle or giving her other pureed foods? Until your baby is 4-6 months old, it's best to give her only formula or breastmilk—giving her cereal or solid foods too early can cause constipation, allergies, and intestinal problems.
• A tiny fissure or crack in the skin around her anus: This could result from a bout of constipation where a hard stool caused a small tear in her anus. It could also result from an usually tight sphincter muscle around the anus.
• Allergy to formula: Infants can develop allergy to formula-both cow's milk and soy formula. A milk or soy allergy can cause small amounts of bleeding in a baby's intestines and leave blood in the stools.
• Infection: In addition to the blood in the stools, watery, explosive, or foul-smelling stools could indicate an intestinal infection with a virus, bacteria, or parasite.

Be sure to see your baby's doctor as soon as possible. The doctor will listen to your description of the problem, examine your baby's abdomen and anus, and may take a sample of the stool or do other tests. The doctor will determine the cause of your baby's stool problem and recommend an appropriate treatment-—this may be as simple as switching to a different type of formula or briefly giving your baby a mild stool softener. But don't give your baby any treatment without the advice of the doctor.