© 2015 by Thieme Medical ublishers, Inc., 333 Seventh Avenue, ew York, NY 10001, USA. Background We previously reported on the overall incidence, management, and outcomes in infants with cardiovascular insufficiency (CVI). However, there are limited data on the relationship of the specific different definitions of CVI to short-term outcomes in term and late preterm newborn infants. Objective This study aims to evaluate how four definitions of CVI relate to short-term outcomes and death. Study Design The previously reported study was a multicenter, prospective cohort study of 647 infants ≥ 34 weeks gestation admitted to a Neonatal Research Network (NRN) newborn intensive care unit (NICU) and mechanically ventilated (MV) during their first 72 hours. The relationship of five short-term outcomes at discharge and four different definitions of CVI were further analyzed. Results All the four definitions were associated with greater number of days on MV and days on O2. The definition using a threshold blood pressure (BP) measurement alone was not associated with days of full feeding, days in the NICU or death. The definition based on the treatment of CVI was associated with all the outcomes including death. Conclusions The definition using a threshold BP alone was not consistently associated with adverse short-term outcomes. Using only a threshold BP to determine therapy may not improve outcomes.