Alterations in the baroreflex occur late in pregnancy in conscious rabbits.

Experiments were performed in conscious rabbits to investigate when during pregnancy cardiac baroreceptor reflex gain decreases. A decrease in gain was first observed after 3 weeks of gestation (-34.1 +/- 4.9 to -15.7 +/- 3.1 beats/min/mm Hg, p < 0.05) and became more pronounced after 4 weeks (-30.2 +/- 4.7 to -8.6 +/- 2.9 beats/min/mm Hg, p < 0.05). These results indicate that the attenuation of baroreflex function does not become fully manifest until late in pregnancy.