Pregnancy alters blood pressure responses to psychological and physical challenge.

The purpose of the study was to evaluate the effect of the substantial changes in female reproductive hormones that occur during normal pregnancy on cardiovascular responses to psychological and physical challenges. Twenty-one healthy normotensive women performed serial subtraction, mirror image tracing, and isometric handgrip exercise tasks prior to pregnancy and again during the second trimester of pregnancy. A control group of 34 healthy women who did not intend to become pregnant and were nonpregnant were also tested in the same protocol twice, 6-10 months apart. Results showed that the pregnant women exhibited a reduced diastolic blood pressure response to all three tasks, relative to their pre-pregnancy levels, whereas nonpregnant controls did not change in their diastolic blood pressure response across time. These results are consistent with the hypothesis that elevations in female reproductive hormones diminish blood pressure responses during challenge because of dampened sympathetic nervous system activity.