ABSTRACT: Background:Excess gestational weight gain (GWG) in pregnant adolescents is a major public health concern. Excess GWG increases risk of pregnancy complications as well as postpartum and offspring obesity and cardiometabolic disease. Prevention interventions for pregnant adults that target lifestyle modification (i.e., healthy eating/physical activity) show insufficient effectiveness. Pregnant adolescents have distinct social-emotional needs, which may contribute to excess GWG. From an interpersonal theoretical framework, conflict and low social support increase negative emotions, which in turn promote excess GWG through mechanisms such as overeating and physical inactivity. Methods:The current manuscript describes the design of a pilot randomized controlled feasibility trial of adolescent interpersonal psychotherapy (IPT) to address social-emotional needs and prevent excess GWG. Up to 50 pregnant, healthy adolescents 13-19y, 12-18?weeks gestation are recruited from an interdisciplinary adolescent maternity hospital clinic and randomized to IPT + usual care or usual care alone. IPT involves 6 individual 60-minute sessions delivered by a trained behavioral health clinician during 12-30?weeks gestation. Sessions include relationship psychoeducation, emotion identification and expression, and teaching/role-playing communication skills. Between sessions, adolescents are instructed to complete a daily journal and to have conversations to work on relationship goals. Outcomes are assessed at baseline, mid-program, post-program, and 3-months postpartum. Primary outcomes are feasibility and acceptability based upon rate of recruitment, session attendance, program acceptability ratings, and follow-up retention. Secondary outcomes are perinatal social functioning, stress, depression, and eating behaviors assessed with validated surveys and interviews; perinatal physical activity and sleep measured via accelerometer; GWG from measured weights; and at 3-months postpartum only, maternal adiposity by dual energy x-ray absorptiometry, maternal insulin sensitivity derived from 2-hour oral glucose tolerance testing, and infant adiposity by air displacement plethysmography. Discussion:This pilot trial will address a key gap in extant understanding of excess GWG prevention for a high-risk population of adolescents. If feasible and acceptable, brief psychotherapy to address social-emotional needs should be tested for its effectiveness to address excess GWG and postpartum maternal/infant health. If effective, such an approach has potential to interrupt an adverse, intergenerational cycle of social-emotional distress, obesity, and cardiometabolic disease among young mothers and their offspring. Trial registration:ClinicalTrials.gov NCT03086161, retrospectively registered.