Continuous oxygen saturation measurements were obtained in 103 pregnant patients and 96 of their newborns by a pulse oximeter during the peripartum period. The parturients received narcotic sedation; epidural, spinal, or general anesthesia; or no analgesia. Seventy-nine patients had oxygen saturation levels over 90% (mean 97.6%), and 24 had one or more oxygen saturation levels less than or equal to 90% (mean 95.6%, P = .001). For all neonates, the mean oxygen saturation was in the "hypoxic range" at one minute (77.6 +/- 11.48%), five minutes (84.4 +/- 7.64%), and ten minutes (89.4 +/- 6.29%). More desaturation episodes were noted in mothers exposed to a central nervous system depressant (P = .041). When mothers with and without desaturation events were compared, no differences were found for age, parity, race, hematocrit, smoking, hypotensive episodes, or delivery route. More maternal desaturation episodes occurred during transport (P = .0016) and while in the recovery room (P = .0003) than in other study periods. Maternal peripartum desaturation events occurred without adverse neonatal effect when prompt treatment was provided. Neonatal hemoglobin oxygen saturation less than or equal to 90% is commonly found within ten minutes after birth and does not always merit the designation of "hypoxia."