To determine the impact of shortened postpartum hospital stays on common clinical phenomena in a sociodemographically diverse, unselected group of general maternity patients. Observational cohort study in which the preapproved hospital stay duration of either 1 or 2 nights was set by third-party payers before each mother's admission. Yale-New Haven Hospital, New Haven, Conn, from June 19 through August 10, 1995. Two hundred forty-four volunteers from among 400 eligible deliveries. Readmission within 1 month of hospital discharge, report of outpatient morbidity and use of outpatient health services within 1 week of discharge, status of breast-feeding during the first post-discharge week, and patient satisfaction. At discharge from the hospital, the hospital stay was regarded as "too short" by 80 (47%) of 171 mothers and 19 (26%) of 73 mothers in the 1- and 2-night groups, respectively (P = .002). Although readmission rates were similar (5% vs 3%, P = .48), the 1-night group reported significantly more morbidity in the newborns (31% vs 16%, P = .03) and averaged more pediatric visits (96 vs 54 per 100 newborns, P = .002). Mothers in the 1-night group also reported more fatigue (49% vs 29%, P = .001) and more worries about their newborns' health (24% vs 11%, P = .02). They were less likely to start breast-feeding (64% vs 77%, P = .06), and, if they started, were somewhat more likely to stop prematurely (14% vs 8%, P = .43). A series of disturbing events was reported only in the 1-night group. In a relatively unselected group, mothers who stayed 1 night after routine vaginal delivery reported more distress and more pediatric problems and had greater use of outpatient health services than mothers who stayed 2 nights.