Advanced Fetal Imaging - Phase II

Inclusion Criteria: * 60 Minute Full Research MRI Scan: * Gestational age between 18 and 40 weeks * AND * Pregnant women with a healthy pregnancy * OR * Pregnant women with a concern for fetal/placental abnormalities referred for a clinical fetal MRI by their obstetrician * OR * Pregnant women with a concern for fetal/placental abnormalities NOT referred for a clinical fetal MRI by their obstetrician * 15 Minute Add-On Research Scan: * Gestational age between 18 and 40 weeks * AND * Pregnant women with a concern for fetal abnormalities referred for a clinical fetal MRI by their obstetrician * AND * The clinical fetal MRI will occur at Boston Children's Hospital Exclusion Criteria: * Pregnant women with a contraindication to MRI (implanted metal, non-removable piercings, pacemaker, etc) * Pregnant women who are claustrophobic * Pregnant women who are medically unstable for an MRI