ABSTRACT
To evaluate whether pregnant women become refractory to the effects of immersion,
we studied 11 healthy women from 26 to 38 weeks' gestation, immersed in 34°C shoulder-deep
water for 4 or 5 consecutive days. The daily immersion diuresis showed no change throughout
the study (p = 0.98: mean, 145 ml, 159 ml, 159 ml, 173 ml, 184 ml, day 1 through day
5, respectively). The range of urine volumes was broad, 35 to 675 ml, depending on
the subject's degree of edema. Immersion produced a significantly larger diuresis
compared with preimmersion values, 162 ml versus 110 ml. Maternal blood pressure and
heart rate consistently fell during immersion, and this effect was maintained for
each day studied. The subjects' hematocrit, hemoglobin, and total protein were unchanged
from a preimmersion sample on day 1 to a postimmersion sample on the last day of the
study. The results of this study indicate that pregnant women do not become refractory
to the hemodynamic and diuretic effects of immersion.
