The article on decreased birthweight associated with increased term induction of labor failed to cite a probable reason for the temporal trend in increased birthweights before 1992. Prior to the availability of cesarean section, women with a small pelvis, and babies of large birthweight, were at risk of significant morbidity and mortality. With cesarean section, selection against a small pelvis or large birthweight has been all but eliminated. As long as a phenotypic trait is variable, heritable, and influenced by selection, evolution will occur. The evidence for these 3 prerequisites for evolution has been elucidated. Birthweight at term has a statistically normal distribution. Birthweight and possibly maternal pelvis size are heritable traits. Selection has clearly acted against a maternal small pelvis or a fetal large birthweight in the past in the developed world and is still a major cause of morbidity and maternal and fetal mortality in developing nations. The maternal pelvis can get smaller over time, and fetal birthweight can get greater over time, because there is now nothing to limit these changes. More frequent induction of labors at term can only delay, but not reverse, this trend.