Research summaries for normal birth.

In this column, the authors summarize four research studies relevant to normal birth. Topics of the studies summarized include the harms of screening for macrosomia late in pregnancy, the risk factors for and impact of postpartum pain in childbearing women, the effects of a breastfeeding approach called "biological nurturing" on reflexive behavior in newborns, and the effects of prenatal yoga on labor and birth outcomes.