The Fourth TrimesterThe first three months of a baby's life is an outside the uterus period of intense development, a biological bridge from fetal life to preparation for the real world. The fourth trimester has more in common with the nine months that came before than with the lifetime that follows. This comprehensive, intimate, and much needed "operating manual" for newborns presents a new paradigm of a baby's early life that shifts our focus and alters our priorities.