Figure 3. Oxygen delivery, fetal fractional O₂ extraction and consumption.

A, umbilical oxygen delivery did not differ between altitudes within each ancestry group (P= 0.77 European, P= 0.99 Andean), but was lower in European than Andean women regardless of altitude (P < 0.001). B, fetal oxygen extraction was similar at low and high altitude in Andean pregnancies (P= 0.96) and in European pregnancies (P= 0.13). However, probably because European women have lower oxygen delivery to begin with, percentage fetal O₂ extraction from the umbilical vein to the umbilical artery was greater in European than in Andean women, regardless of altitude (†P < 0.01). The range for fetal O₂ extraction was 35–93% at low altitude and 20–93% at high altitude. C, oxygen consumption per kg fetal weight was similar in all four groups.