Maternal blood gas status of four racial groups in late pregnancy A preliminary study.

The blood gas/acid-base status of normal healthy Black, Indian, Coloured and White pregnant women was measured. All groups exhibited evidence of hyperventilation (decreased) PaCO2 relative to the non-pregnant state, with compensatory metabolic adjustment. Arterial oxygen tensions (PaO2) were significantly lower in the Black and Indian groups compared with their White counterparts (P less than 0,01). Differences between the former two series and the Coloured group, however, just failed to reach statistically significant levels (0,1 less than P less than 0,05). The possible causes of a lowered PaO2 during pregnancy and their relevance to obstetric anaesthesia are discussed. A further study using a more sophisticated protocol is planned in an attempt to delineate the causes of these important differences.