Comparison of cardiovascular reflex tests and blood pressure measurement in prediction of pregnancy-induced hypertension.

A changed pressor response to some cardiovascular reflex tests and an increase in midtrimester blood pressure has been reported to precede the appearance of hypertension in pregnancy-induced hypertensive disorders (PIH). In order to compare the value of midtrimester blood pressure with the cardiovascular reflex tests, in predicting the risk of PIH, the Valsalva manoeuvre, the orthostatic test, the deep breathing test and the isometric handgrip test were performed prospectively in 94 women studied once at 21-29 weeks of pregnancy. Eight subjects developed PIH 3-12 weeks after the testing. The resting blood pressure in midpregnancy was related to PIH later in pregnancy. The most powerful measures were the supine diastolic resting blood pressure (odds ratio, 1.24; 95% confidence limits, 1.08-1.43) and the mean arterial pressure (odds ratio, 1.25; 95% confidence limits, 1.09-1.44). Signs of autonomic dysfunction were found in 37% of the patients developing PIH and in 8% of the healthy remaining subjects (P = 0.04). The results show that the preclinical stage of PIH is associated with some changes in the neural hemodynamic control. However, cardiovascular reflex tests do not add much information on the risk of PIH compared with measuring of the resting blood pressure during mid-pregnancy.