[Use of oxygen therapy during labour and acid-base status in the newborn].

The effect of supplemental maternal oxygen therapy on acid-base status has for years been a subject of controversies. There is still no general agreement about oxygen administration in pregnancy or in labour. Many clinicians believe that in normal pregnancy maternal oxygen treatment has merely negligible, if any, influence on the foetus. Maternal oxygen therapy has frequently been suggested when oxygen supply to the foetus was insufficient, viz. in antepartum or intrapartum hypoxia. The aim of this study was to determine whether a brief maternal hyperoxygenation during caesarean section or during the second stage of normal delivery affects cord blood acid-base status measured at birth. Patients with uneventful term pregnancy admitted to the delivery room in spontaneous labour or indicated for elective caesarean section were matched and prospectively ascribed to the control or treatment group. The latter received 60% oxygen for ca. 10 min at 15 L/min by a face mask. We studied 41 normal term infants of healthy mothers (24 from caesarean sections, the remaining 17 delivered vaginally). The control group consisted of normal newborns chosen according to the same criteria except that their mothers had no oxygen supplementation. Immediately after delivery, umbilical cord paired blood samples were drawn. Arterial and venous specimens were analysed for blood gases and acid-base balance parameters. Statistical analysis assisted by computer software was performed using Mann-Whitney U test. A p value < 0.05 was considered significant. All tested parameters related to the acid-base status and blood gases were similar in the treatment and control groups. Concluding, a short period of maternal hyperoxygenation either in the second stage of vaginal spontaneous delivery or during caesarean section did not affect umbilical cord blood acid-base status measured at birth.