$Unique_ID{BRK01560}
$Pretitle{}
$Title{Does the Heart of the Mother Change While She is Pregnant?}
$Subject{heart size Pregnancy Childbirth Mother Pregnant rate rates Blood
pressure pregnancies cardiac output aorta ventricle ventricular circulatory
system circulation pressures ventricles circulation}
$Volume{K-3,G-3}
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Copyright (c) 1991-92,1993   Tribune Media Services, Inc.


Does the Heart of the Mother Change While She is Pregnant?


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QUESTION:  Since there are many apparent changes in a woman's body during
pregnancy, I wondered if her heart might also be affected by the pregnancy.
Does the heart of the mother change while she is pregnant?

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ANSWER:  It most certainly does.  During normal pregnancy, labor and delivery,
a good many changes take place, providing physicians with a special
opportunity for observing important cardiac adjustments during a temporary
state of high stress.
     To begin with, heart rate increases up to fifteen beats per minute above
nonpregnant levels, with the most significant increases occurring before the
eighth week of pregnancy.  Blood pressure can either increase or decrease,
depending on the woman's age and whether she's had previous pregnancies.
Levels appear to increase with advancing age and decrease if previous
pregnancies existed.
     In addition, cardiac output (the amount of blood the heart pumps out) at
rest increases during pregnancy, from 30-50 percent above normal, peaking at
the end of the second trimester.  It is believed that the increased heart rate
is responsible for this change in cardiac output, as well as the increased
stroke volume (amount of blood that is pumped out with each beat of the
heart).  The resistance to blood flow in the arteries of the body decreases
during pregnancy, and together with the increased cardiac output, blood flow
to various organ systems is altered as well.  Uterine and kidney blood flow
markedly increase, as well as blood flow to breasts, skin, limbs, and mucous
membranes.
     One of the most significant changes, however, involves the left
ventricle, or lower left chamber of the heart which pumps oxygenated blood out
through the aorta to all the tissues of the body.  Left ventricular volume and
chamber size gradually increase throughout pregnancy resulting in the
enlargement of the heart's cavities and wall mass.  This enlargement
contributes to the increased cardiac output.  However, despite the dimensional
changes, the heart's function and wall stress remain normal.  Within five
weeks after delivery, all blood flow, structural, and functional changes are
back to pre-pregnancy values, indicating that the heart is a remarkably
adaptive organ which can respond to the changing demands placed upon it by
the needs of the pregnancy.  Physicians are hopeful that these findings will
one day lead to insights concerning possible treatment for the problems of an
ailing heart, and the need for it to adjust to stress.

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The material contained here is "FOR INFORMATION ONLY" and should not replace
the counsel and advice of your personal physician.  Promptly consulting your
doctor is the best path to a quick and successful resolution of any medical
problem.