Difference between central and peripheral blood pressure in healthy and hypertension-complicated pregnancy

Hemodynamics of a pregnant woman differ and change over time depending on the age of gestation. In the general population, brachial-aortic systolic pressure (SBP-AoSP) difference is known and discussed, whereas in pregnancy, it is not established. On the basis of theoretical premises it is probably different and changes with time of gestation. As AoSP is more relevant for internal organs, also for placental perfusion, and still not widely available in clinical practice, knowledge of the average SBP-AoSP difference in a healthy and complicated pregnancy could be of additional value for the management of pregnancy hypertension. The aim of this study was to assess the SBP-AoSP difference in healthy and hypertensive pregnancies in comparison with nonpregnant controls.

Aortic blood pressure with applanation tonometry and brachial blood pressure under standardized conditions were measured monthly and once postpartum in 36 normotensive pregnant women (age: 29.6±4.8 years) and compared with 25 hypertensive pregnancies (age: 30.5±5.4 years) before antihypertensive treatment implementation and with 25 nonpregnant controls (age: 30.2±5.5 years).

In hypertensive pregnancies, the SBP-AoSP difference was smaller throughout the entire pregnancy than in healthy pregnancies (in the second and third trimester: 14.44 vs. 15.7 mmHg, P=0.002, and 12.9 vs. 14 mmHg, P=0.02), and smaller than that in nonpregnant controls (14.88 mmHg, for third trimester, P=0.036). Comparison of healthy pregnancy and controls showed an insignificant increase in SBP-AoSP difference in the first and second trimester, whereas in the third trimester, because of a larger increase of AoSP, the SBP-AoSP difference was smaller than that in nonpregnant controls (14.66 mmHg, P>0.05).

A reduced SBP-AoSP difference was found in hypertensive pregnancies compared with healthy controls, which may signify a narrower safety margin for complications. Comparison of pregnant women with nonpregnant controls showed that a significant difference for the SBP-AoSP difference was present only for the postpartum period.