Pregnant baboons received general anesthesia and fetuses were delivered by primary caesarean section. Extremely premature-born animals (Table 2) were weighed and placed in plastic wrap to prevent hypothermia. Baboons then received intramuscular ketamine (10 mg/kg; Putney), Vitamin K (0.5 mg; Hospira). We then intubated the animals orotracheally, using uncuffed endotracheal tubes (Vygon) and slowly instilled 120 mg Poractant alfa (Chiesi Farmaceutici) via the lateral port of the tube. During this procedure, animals were started on pressure-controlled, continuous mandatory ventilation (PC-CMV) with a rate of 40 min−1, peak inspiratory pressure (PIP) of 30 cmH2O, positive end expiratory pressure (PEEP) of 5 cmH2O and a fraction of inspired oxygen (FiO2) of 0.4 utilizing a VIP Gold Bird (CareFusion) respirator. Respiratory support was continuously adapted, based on heart rate and pre-ductal peripheral oxygen saturation (SPO2). A 21 G umbilical arterial catheter (UAC; Covidien/Medtronic) and a 24 G peripheral inserted central venous catheter (PICC; Vygon) were placed as well as an orogastric tube. The mothers were closely monitored by the attending veterinarian staff after surgical repair of incisions and returned to their colonies within 2 to 4 weeks after the surgery.