Your baby weighs about 5.25 ounces and is 5-1/2 inches long from crown to rump, or about the size of a large pickle. Your baby's digestive system is starting to produce meconium, its first fecal matter. Some new moms are scared at the sight of it in their newborn’s diapers and think something must be wrong with their baby, but it’s perfectly normal and will only last a few days after birth.