Oxygen utilization in newborns at delivery.

Aims: To evaluate the arteriovenous (AV) pH difference in cord blood as a possible indicator of fetal O2-utilization at delivery. Furthermore to examine which maternal, fetal and obstetrical factors lead to elevated O2-utilization. Methods: In this retrospective study all singleton live births, delivered within a four-month period at the University Hospital in Innsbruck, Austria, were analyzed. In total 491 deliveries were evaluated. Arterial and venous cord blood samples were collected at birth and analyzed by using a Radiometer ABL 510. Results: Spontaneous deliveries showed a highly significant elevation in AV-difference (pH 0.10) as compared to cesarean sections (pH 0.05). In spontaneous births, the AV-difference was high in the case of low arterial cord blood pH (P<0.01), as well as in nuchal cord (P<0.01), high parity (P<0.01), very short labor (P<0.05) and elevated birth size and weight (P<0.05). Conclusions: As a result of increased fetal stress at birth, spontaneous delivery leads to higher O2-utilization than cesarean section, which is detectable in an elevated AV-difference. The AV-difference in combination with absolute pH-values can be used for the objective evaluation of fetal O2-utilization and consecutively the fetal stress at birth. [ABSTRACT FROM AUTHOR]