Pediatrician Mark Sloan has attended nearly 3,000 births, giving him a wealth of experience to draw on for this exploration of childbirth and newborn life. But Sloan brings more than experience to his first book: He is an intelligent, warm, and funny writer, and nearly every page of Birth Day informs, fascinates, and delights. Shifting between history, science, and memoir, Sloan covers everything from the rise of cesarean sections and epidurals to the functioning of the five senses at birth to the debate over circumcision. He includes self-deprecating anecdotes from his days as a medical student on his obstetrics rotation (“You know, if you can’t tell a baby’s head from its ass, maybe you’re in the wrong business,” his resident remarks after bailing him out during a breech birth), vivid recollections of his own children’s arrivals, and stories of memorable patients. One of the most entertaining of these is the aggressive new father who tries to get Sloan to change his son’s Apgar score — which measures things like a newborn’s heart rate and coloring — from a nine to a ten, which Sloan likens to “arguing over the baby’s birth weight.” But the good doctor even treats the bully he dubs “Apgar Guy” with compassion, noting that “being rational about your own baby isn’t part of most new parents’ emotional toolboxes.” Since he’s called to the delivery room when the fetus’s health is in question, one can only assume Sloan has witnessed his share of unhappy outcomes. But he keeps the focus positive here, making this an edifying, reassuring read for parents-to-be.