The United States currently ranks 20th in infant mortality among industrialized countries due largely to its high low birthweight (LBW) rate. Recently, home visiting of pregnant women at risk for LBW has been advocated by several national groups to augment routine prenatal care and improve maternal and infant outcomes. Such additive care will increase health care costs unless there are clear improved patient outcomes. The purpose of this randomized clinical trial is to compare maternal and infant outcomes and cost of care between 2 groups of women at high risk for delivering LBW infants: a control group (89) that will receive routine care; and in intervention group (89) in which half of routine prenatal physician office/clinic care will be substituted with nurse specialist care delivered via home visits and telephone contact. Both high risk group (controls and intervention) will be comprised of pregnant women with diabetes, chronic hypertension diagnosed or at high risk of preterm labor. The study will examine: (1) maternal outcomes: adequacy of prenatal care; morbidity; weight gain and hemoglobin; postpartum physician visits; continued employment/school attendance; affect; satisfaction with care (2) infant outcomes: gestational age; mortality and morbidity; health status over 1 year; placement and child abuse (3) cost; nurse specialist services; (4) major interventions used by nurse specialists. Both groups will be followed 1 year post delivery. Data analysis will include MANOVA, chi- square and t-tests. Study outcomes will provide important data on: nurse specialist home visiting effects on high risk pregnant women and their infants; relative cost of this substitutive care versus routine or additive home visiting care; major interventions needed in home visiting care of this high risk group. Data will be important to researchers, providers, insurers and policy maker.