What's normal: Baby pee is much like grown-up urine. In the first few days after birth, however, you might see a reddish-pink dust in your baby's diaper. It's just a chemical reaction between his early urine (which can be more concentrated) and the diaper, and there's no need to worry, explains Dr. O'Keeffe. After the first week of life, expect at least six wet diapers a day.
What's not: If your baby is acting fussy, having fewer wet diapers than usual, producing crystallized urine, and crying but not making tears, he may be dehydrated. This is usually a sign that he's sick, but it also may be an indication that he's not getting enough breast milk or formula. Either way, you should talk to your doctor: Some pediatricians recommend giving over-the-counter pediatric electrolyte solutions to very dehydrated babies, says Dr. Altmann. Cloudy or foul-smelling urine may be a sign of a urinary-tract infection, which is usually accompanied by fever, sluggishness, and vomiting. Call your pediatrician if your infant is showing any of these symptoms.