Preterm birth is a major cause of neonatal morbidity and mortality in the US and is a major health burden. The overall frequency of preterm birth is 12%, and a significant fraction of cases can be attributed to genetic rather than environmental causes. One explanation for the high rate of preterm birth is that humans have evolved a shortened period of gestation to compensate for adaptations related to cognition and bipedal locomotion: an increase in brain size and a narrowing of the pelvis. The developmental prematurity of all human neonates compared to other primates supports this hypothesis and suggests that the same genes involved in the evolution of human parturition are also involved in preterm birth. Based on this idea, we have developed a comparative genomics screen to identify genes and regulatory sequences that have evolved rapidly along the human lineages as candidates for association with preterm birth. In collaboration with Dr. Lou Muglia in the Department of Pediatrics, we have begun identifying candidate genes and testing them in a case-control study design.