"Your child can achieve great things." A few years ago, pregnant women in four corners of the world heard those words and hoped they could be true. Among them were Esther Okwir in rural Uganda, where the infant mortality rate is among the highest in the world; Jessica Saldana, a high school student in a violence-scarred Chicago neighborhood; Shyamkali, the mother of four girls in a low-caste village in India; and Maria Estella, in Guatemala's...