Diaper close-up: A dark-greenish, sticky, tarlike goop. There isn't much of an odor, but it can smell like licorice.
When it happens: Within 24 to 48 hours after birth
What's going on? Meconium. The sludgy stuff is the waste that your newborn has been accumulating in utero -- amniotic fluid, cells that flake off his skin and hair, and intestinal secretions. It's excreted within 24 to 48 hours after birth, so your baby may pass most of his meconium in the hospital.
How to handle: If you're nursing, your colostrum (the first milk) acts as a natural laxative; the initial poop may take longer for formula-fed babies. Meconium can be hard to wash off -- a dollop of petroleum jelly or mineral oil can help. If your newborn doesn't poop within a few days of being born, call your doctor.