Oxygen saturation response to exercise in healthy pregnant women: a simple protocol and normal range.

Measurement of oxygen saturation on excercise, using a pulse oximeter, has been advocated in the assessment of women with shortness of breath in pregnancy. However, there is currently no standard protocol for this. The aims of this study were to determine the normal range for oxygen saturation at rest and on moderate exercise in healthy women from 24 weeks gestation and to evaluate a simple, widely applicable exercise protocol in which women walked at their own pace for 100 metres then up two flights of stairs. The protocol achieved 60-85% maximum predicted heart rate in 99% of women at a median gestation of 31(+3) weeks, with a wide range of Hb and BMI. There was a mean 0.3% fall in oxygen saturation on exertion but oxygen saturation did not fall below 95% in any of the women.