Normative oxygen saturation values for pregnant women at sea level

Objective: To develop normative ranges of maternal arterial oxygen saturation (SpO(2)) for women residing at sea level throughout gestation and postpartum.Materials and Methods: Healthy, nonsmoking, non-laboring pregnant women, with no obstetrical risk factors, were recruited into this longitudinal study performed at The Stamford Hospital (elevation sea level). Maternal SpO(2) was measured in the dominant index finger while breathing room air with a Nelcor N-200 pulse oximeter and DS-100A sensor (Nellcor Puritan Bennett, Pleasanton, CA) at set antepartum (AP) and postpartum (PP) intervals. Oxygen saturation was measured in the following positions: sitting, lying on the left then right side, knee-chest, and supine. Five minutes were allowed between measurements. Measurements were taken at 12, 24, and 36 weeks of gestation and then at 12 weeks postpartum for each patient.Results: Thirty-six patients were initially enrolled. Three were excluded from this study, secondary to loss of follow-up (1), preterm delivery at 35 weeks (1), and complicated placenta previa (1). Of the 33 patients who remained in the study 5 have delivered and undergone postpartum evaluation. SpO(2) values (%) are summarized as mean +/- 2 SD in the Table.Conclusion: Preliminary data in this ongoing descriptive longitudinal study suggest that maternal SpO(2) is at least 97% throughout pregnancy for healthy, non-smoking women residing at sea level. These normative data may be useful in managing pregnant women at risk for hypoxia.