Mid-trimester blood pressure drop in normal pregnancy: myth or reality?
- 1 April 2011
- journal article
- Published by Ovid Technologies (Wolters Kluwer Health) in Journal of Hypertension
- Vol. 29 (4), 763-768
- https://doi.org/10.1097/hjh.0b013e328342cb02
Abstract
Current dogma states that there is a mid-trimester fall in blood pressure (BP) in uncomplicated pregnancy. In the early stages of a longitudinal study of microcirculatory changes in pregnancy, we noted an absence of this mid-trimester fall. We prospectively studied this phenomenon in all our subsequent recruits. From a total of 326 women, 255 primigravid white women normotensive at booking and after delivery were studied. Serial BP measurements were taken under controlled conditions through to 38 weeks gestation. BP measurements by midwives were extracted from the case notes of 51 women within this cohort and analysed to validate the results. SBP progressively increased from the first trimester through to 38 weeks gestation. The increase from baseline at 13 weeks was significant when compared with measurements at 22 weeks [mean difference: 2.8 mmHg; 95% (confidence interval) CI 1.9-3.7], 28 weeks (mean difference: 5.0 mmHg; 95% CI 3.5-6.5) and 36 weeks (mean difference: 7.7 mmHg; 95% CI 6.2-9.1). DBP showed a nonsignificant dip at 22 weeks (mean difference: -0.12 mmHg; 95% CI -0.92 to 0.68), a nonsignificant increase at 28 weeks (mean difference: 2.0 mmHg; 95% CI 0.80-3.2) and a significant increase at 36 weeks (mean difference: 6.0; 95% CI 4.6-7.3). In the validation cohort, the SBP (P=0.0001) and DBP showed an increasing trend (P=0.0001). BP measured under controlled conditions showed a progressive rise in pregnancy, with no significant mid-trimester drop. The findings were replicated in the routine antenatal clinic measurements.This publication has 23 references indexed in Scilit:
- Vasodilator factors in the systemic and local adaptations to pregnancyReproductive Biology and Endocrinology, 2009
- Cross sectional study of automated blood pressure measurements throughout pregnancyBJOG: An International Journal of Obstetrics and Gynaecology, 2004
- Blood Pressure Patterns in Normal Pregnancy, Gestational Hypertension, and PreeclampsiaHypertension, 2000
- A longitudinal study of maternal hemodynamics during normal pregnancyObstetrics & Gynecology, 1996
- Measurements of Blood Pressure, Oedema and Proteinuria in a Pregnant Population of New ZealandAustralian and New Zealand Journal of Obstetrics and Gynaecology, 1995
- Serial study of factors influencing changes in cardiac output during human pregnancyAmerican Journal of Physiology-Heart and Circulatory Physiology, 1989
- A prospective study of blood pressure in pregnancy: Prediction of preeclampsiaAmerican Journal of Obstetrics and Gynecology, 1985
- Blood pressure, the renin-aldosterone system and sex steroids throughout normal pregnancyThe American Journal of Medicine, 1980
- CIRCULATORY ADJUSTMENTS OF PREGNANCYClinical Obstetrics and Gynecology, 1960
- Cardiodynamic and electrocardiographic changes in normal pregnancyAmerican Heart Journal, 1936