Maternal Blood Pressure Adaptation in the First Trimester of Pregnancy

ABSTRACT

Normal changes in blood pressure during pregnancy are well documented in the second and third trimesters. Little is known about first-trimester changes, particularly compared with preconceptional values. This knowledge might allow for early prediction of conditions such as preeclampsia or intrauterine growth restriction. Prior studies utilized a laboratory setting. We conducted this retrospective study to compare blood pressure readings in early pregnancy with preconceptional values in the clinical setting. The records of 44 healthy normotensive nonsmoking women with a body mass index <30 and an uncomplicated appropriately grown singleton term delivery were reviewed. Preconceptional blood pressures values were compared with values at five periods (weeks 1 to 8, 9 to 16, 17 to 23, 24 to 32, 33 to 40). There was no difference in blood pressure parameters when comparing preconceptional values with period 1. The mean and systolic arterial pressures decreased significantly in periods 2 and 3. We were unable to demonstrate significant change in any blood pressure parameter in the first 8 weeks of pregnancy. This work should be repeated in patients who subsequently develop preeclampsia, spontaneous abortion, or intrauterine growth restriction to determine if early changes might be evident in early pregnancy to identify patients destined to develop pregnancy complications.

Blood pressure - pregnancy - screening test - first trimester

REFERENCES

• 1 Robson S C, Hunter S, Boys R J, Dunlop W. Serial study of factors influencing changes in cardiac output during human pregnancy.  Am J Physiol. 1989;  256(4 Pt 2) H1060-H1065
• 2 Moutquin J M, Rainville C, Giroux L et al.. A prospective study of blood pressure in pregnancy: prediction of preeclampsia.  Am J Obstet Gynecol. 1985;  151 191-196
• 3 Duvekot J J, Cheriex E C, Pieters F A, Menheere P P, Peeters L H. Early pregnancy changes in hemodynamics and volume homeostasis are consecutive adjustments triggered by a primary fall in systemic vascular tone.  Am J Obstet Gynecol. 1993;  169 1382-1392
• 4 Capeless E L, Clapp J F. Cardiovascular changes in early phase of pregnancy.  Am J Obstet Gynecol. 1989;  161(6 Pt 1) 1449-1453
• 5 Clapp III J F, Seaward B L, Sleamaker R H, Hiser J. Maternal physiologic adaptations to early human pregnancy.  Am J Obstet Gynecol. 1988;  159 1456-1460
• 6 Clapp III J F, Capeless E L. Cardiovascular function before, during, and after the first and subsequent pregnancies.  Am J Cardiol. 1997;  80 1469-1473
• 7 Frohlich E D, Grim C, Labarthe D R et al.. Recommendations for human blood pressure determination by sphygmomanometers: report of a special task force appointed by the steering committee, American Heart Association.  Hypertension. 1988;  11 209A