Dr. O'Brien's primary research interests include the impact of sleep disruption in pregnancy and the association with adverse maternal and fetal outcomes, including fetal growth restriction and stillbirth, as well as intervention therapies to optimize sleep in the perinatal population. She was responsible for developing collaborations between the Division of Sleep Medicine and the Department of Obstetrics and Gynecology and has held several NIH grants, foundation grants, and donor funds in support of this work. In addition to pregnancy, Dr. O’Brien’s work includes the impact of sleep disruption on fertility/infertility. She is also involved in clinical trials of treatment of sleep-disordered breathing in children, both in typically developing children and those with medical conditions such as cerebral palsy, Trisomy 21, cleft palate repair, craniofacial anomalies, and Williams Syndrome. Dr. O'Brien participates in the training of sleep medicine fellows and acts as a mentor for students, post-docs, fellows, and junior faculty interested in sleep research. She has published over 140 original manuscripts, over 35 invited reviews and book chapters, and has given numerous invited lectures around the world. In addition, she serves on NIH study sections, is part of the Medical Advisory Team of the Star Legacy Stillbirth Foundation, and has served as a reviewer for over 90 medical journals, including the American Journal of Perinatology, American Journal of Respiratory and Critical Care Medicine, Archives of Disease in Childhood, British Medical Journal, British Journal of Obstetrics and Gynecology, Human Reproduction, International Journal of Gynecology and Obstetrics, New England Journal of Medicine, Obstetrics and Gynecology, Pediatrics, Sleep, Sleep Medicine, Thorax, and The Lancet.