Premature neonates with bronchopulmonary dysplasia (BPD) frequently present borderline hypoxemia and the risk for oxygen desaturation may increase in relation to the posture. Our aim was to see if infants with BPD experience severe hypoxemia (SaO2 < 85%) in a hammock, a 'containing' posture considered advantageous to neuromotor and relational development of the preterm. Fifteen pulse oximetry recordings (Ohmeda B105 3760 Pulse Oximeter) were obtained in 15 subjects (range of gestational age and postnatal age 27-30 and 33-48 weeks, respectively; range of birth weight and body weight at entrance to the study 0.64-1.35 and 0.97-2.24 kg, respectively) before, during and after placement in a hammock; each testing period lasted 15 min, and each baby served as his or her own control. BPD preterm infants were receiving oxygen therapy by continuous flow standard nasal cannulas (FiO2 > 25%, < 40%). The analysis of the data, that have a rough gaussian distribution, indicates a worsening of SaO2 in the hammock position. In fact, mean +/- SEM, median and range of the SaO2 values in pre- and posthammock position are comparable, but are significantly different at 99.9% confidence level (CL) in prehammock vs. hammock posture and at 98% CL in posthammock vs. hammock posture. Moreover, the percent of time with SaO2 < 85% during the periods recorded increased about 10 +/- 5% in a hammock (24 +/- 4%), in comparison to pre- (14 +/- 3%) and posthammock position (15 +/- 3%). These results suggest that oxygen-dependent BPD preterm infants in the hammock posture may experience severe hypoxemia that in part limits the possible advantages of the 'containment'.