Objective: To describe the development of an artificial placenta (AP) system in sheep with learning curve and main bottlenecks to allow survival up to one week.
Methods: A total of 28 fetal sheep were transferred to an AP system at 110-115 days of gestation. The survival goal in the AP system was increased progressively in three consecutive study groups: 1-3 h (n = 8), 4-24 h (n = 10) and 48-168 h (n = 10).