Postural influence on maternal capillary oxygen and carbon dioxide tension.

The effect of posture on maternal capillary blood Po(2) and Pco(2) was studied in pregnant and non-pregnant women. There was a significant decrease of Po(2) (mean 13.0 mm. Hg) and significant decrease of Pco(2) (mean 2.4 mm. Hg) when pregnant women sat up, but these changes did not occur in the non-pregnant. These findings may be relevant to debate on the optimum posture for labour.