CARDIOVASCULAR FUNCTION BEFORE, DURING, AND AFTER THE FIRST AND SUBSEQUENT PREGNANCIES

This study was designed to test the hypothesis that the vascular remod eling of pregnancy begins early, persists for at least 1 year after de livery, and is accentuated by a second pregnancy, Serial estimates of heart rate, arterial pressure, left ventricular volumes, cardiac outpu t, and calculated peripheral resistance were obtained before pregnancy , every 8 weeks during pregnancy, and 12, 24, and 52 weeks postpartum in 15 nulliparous and 15 porous women using electrocardiography, autom ated manometry, and M-mode ultrasound, During pregnancy, body weight i ncreased 14.5 +/- 1.8 kg and returned to prepregnancy values 1 year po stpartum, Heart rate peaked at term 15 +/- 1 beat/min above prepregnan cy levels (57 +/- 1 beat/min), Mean arterial pressure reached its nadi r (-6 +/- 1 mm Hg) at 16 weeks, returning to baseline at term, The inc reases in left ventricular volumes and cardiac output (2.2 +/- 0.2 L/m in) peaked at 24 weeks as did the 500 +/- 29 dynes.cm.s(-5) decrease i n peripheral resistance, and their magnitude was significantly greater in the parous women, Postpartum they gradually returned toward baseli ne but remained significantly different from prepregnancy values in bo th groups at 1 year, We conclude that cardiovascular adaptations to th e initial pregnancy begin early, persist postpartum, and appear to be enhanced by a subsequent pregnancy, We speculate that persistence of t hese changes may lower cardiovascular risk in later life. (C) 1997 by Excerpta Medica, Inc.