CHANGES IN MATERNAL HEART DIMENSIONS AND PLASMA ATRIAL-NATRIURETIC-PEPTIDE LEVELS IN THE EARLY PUERPERIUM OF NORMAL AND PREECLAMPTIC PREGNANCIES

Objective To measure plasma atrial natriuretic peptide (ANP) in relati on to maternal haemodynamics and body fluid balance in the early puerp erium following uncomplicated pregnancy and pre-eclampsia. Design A lo ngitudinal study from late pregnancy and into the early postpartum per iod (days 1 to 3 and days 4 to 6) compared with nonpregnant controls. Subjects Eleven women with uncomplicated pregnancies, 12 women with pr e-eclampsia and 12 healthy, nonpregnant women. Main outcome measures M aternal heart dimensions determined by M-mode echocardiography, concen trations of ANP, and daily urine output and sodium excretion. Results After delivery increases in left atrial dimensions, represented as mea n (SEM), from 33.2 (1.6) to 37.7 (1.7) mm and ANP levels from 7.9 (1.1 ) to 19.0 (2.7) pmol/L were observed at 1-3 days postpartum in normal pregnant women, but we were not able to demonstrate a significant incr ease in diuresis and natriuresis. Ln the third trimester left atrial d imensions (38.4 (1.2) mm) and ANP levels (15.4 (2.2) pmol/L) were grea ter in pre-eclampsia. ANP levels rose further in pre-eclamptic women i n the early puerperium (27.4 (7.4) pmol/L) with an increase in diuresi s and natriuresis, while left atrial dimensions did not change signifi cantly (39.4 (1.7) mm). A pericardial effusion was found in 11 pre-ecl amptic but in only three healthy pregnant women. Conclusions A concomm itant increase in left atrial dimensions and ANP in the early puerperi um following uncomplicated pregnancies is consistent with the mechanis m of atrial stretch as a stimulus for ANP release, although the biolog ical significance of this finding remained unclear A significantly hig her release of ANP in the early puerperium after pregnancies complicat ed by pre-eclampsia may be a mechanism which promotes the renal elimin ation of excessive body fluids and sodium.