The overall purpose of this study was to determine if a combined medical and biobehavioral intervention would prevent PTBs and reduce healthcare costs in a sample of women who have had a prior PTB. The medical intervention was conventional prenatal and postpartum clinic care. The biobehavioral intervention included certified nurse midwife home visitors who engaged women in an integrated System of Care (SOC) during their prenatal care. Care continued during the first 18 months of the infant's life by maternal-child nurse visitors. Home visits were in addition to regularly scheduled conventional prenatal and postpartum clinic care. Main study questions were: