Serial changes in cardiac output during normal pregnancy: a Doppler ultrasound study.
OBJECTIVE
To determine the direction and magnitude of change in cardiac output (CO) during pregnancy.


METHODS
We performed serial measurements of CO on five occasions from 24 weeks gestation to term and once during the puerperium in 26 normal pregnancies (156 measurements) using Doppler ultrasound measurement of flow velocity profiles and aortic root cross sectional area.


RESULTS
CO increased to 7.0 l/min by 32 weeks gestation, 49% above baseline values. It fell to 5.7 l/min by term, 21% above baseline. The peak in CO corresponded with an increase in heart rate to 91 beats/min, 32% above baseline. Stroke volume peaked at 36 weeks gestation, by which time CO had already begun to decline.


CONCLUSIONS
CO increased in a linear fashion until 32 weeks gestation and then declined to term, but to a value still greater than the postpartum baseline. These findings have obvious management implications for patients with serious heart disease complicating pregnancy.
Hennessy
T G
TG
National Maternity Hospital, Dublin, Ireland.
MacDonald
D
D
Hennessy
M S
MS
Maguire
M
M
Blake
S
S
McCann
H A
HA
Sugrue
D D
DD
D001794:Blood Pressure; D002302:Cardiac Output; D015150:Echocardiography, Doppler; D005260:Female; D006339:Heart Rate; D006801:Humans; D011247:Pregnancy / Q000502:physiology*; D013318:Stroke Volume