The first three months of a baby's life he/she is considered a newborn and this time is referred to as the fourth trimester. It's the time needed for the baby to gain the maturity to be able to handle living outside the womb. No, the idea isn't that she is now mature enough to live on her own, but that she is mature enough to do things like soothe herself, handle the stimulation in the world, and her senses are now more well-developed. The colicky type behaviors are supposed to end at this time and most babies begin to enjoy the world more. In other words, the end of the fourth trimester is what all the books encourage parents to hold on for when their newborns are inconsolable. When Sarah Graves was first born we used the techniques taught in Happiest Baby on the Block to soothe her. This meant bouncing her so that her head jiggled, swaddling her, making a loud "sshhh" noise in her ear, and giving her lots of opportunities to suck. At the time, it felt l...