What You Need to Know About Heart Rate During Pregnancy
What You Need to Know About Heart Rate During Pregnancy
Pregnancy
is an exciting time, no doubt about it. But let's be honest: It also
comes with about a billion questions. Is it safe to work out? Are there
restrictions? Why the heck is everyone telling me I need a heart rate
monitor?
If
you're not careful, the questions can quickly become overwhelming, and
it's tempting to sit on the couch for the entire pregnancy. When I first
became pregnant with twins, it was labeled "high-risk," as all multiple
pregnancies are. Because of that, I was slapped with all sorts of
restrictions on activities. Being a very active person in my day-to-day
life, this was really hard for me to wrap my brain around, so I went in
search of multiple opinions. One piece of advice I got time and time
again: Get a heart rate monitor, and keep you heart rate below "X" while
exercising.
But
the truth is that the guidelines about exercising while pregnant have
been adapted from overall physical activity and public health
literature, reports the National Institute of Health (NIH). In 2008, the
U.S. Department of Health and Human Services (HHS) issued comprehensive
guidelines on physical activity, and included a section stating that
healthy, pregnant women should begin or continue moderate-intensity
aerobic activity during pregnancy, accumulating at least 150 minutes per
week. But there's little information about heart rate, specifically.
And in 1994, the American Congress of Obstetricians and Gynecoligists
(ACOG) removed the recommendation that many obstetricians still
follow—keeping heart rate to less than 140 beats per minute—because it
was found that tracking heart rate during exercise is not as
effective as other monitoring methods.
What
gives? We're constantly told to measure our heart rate during
exercise as a way of really deciphering how hard we're working. So why
wouldn't we do the same during a pregnancy, when there's another life to
monitor?
Using
heart rate as a measure of exertion might be unreliable in pregnancy
because of the many physiological changes that happen in order to
support a growing fetus," says Carolyn Piszczek, M.D., an OBGYN in
Portland, OR. Example: Blood volume, heart rate, and cardiac output (the
amount of blood your heart pumps per minute) all increase in a
mother-to-be. At the same time, systemic vascular resistance—AKA the
amount of resistance that the body has to overcome in order to push
blood through the circulatory system—decreases, says Sara Seidelmann,
M.D., Ph.D., researcher in the cardiovascular division at Brigham and
Women's Hospital in Boston. All of those systems work together to create
a balance that allows enough blood flow to support both mom and baby
during exercise. "Because of all of these changes, your heart rate may
not increase in response to exercise in the same way that it did before
pregnancy," says Seidelmann.
So
if monitoring heart rate is out, what should you do instead? Pay
attention to perceived moderate exertion—otherwise known as the talk
test. "During pregnancy, if a woman is able to comfortably carry on a
conversation while exercising, it is unlikely that she is overexerting
herself," says Seidelmann.
Now,
what does this all mean for working out while pregnant? According to
the Centers for Disease Control Prevention (CDC), pregnant women should
aim to get at least 150 minutes of moderate intensity aerobic activity
every week. Moderate intensity is defined as moving enough to raise your
heart rate and start sweating, while still being able to talk
normally—but definitely not sing. (Usually, a brisk walk is close the
correct level of exertion.)
And
don't forget, working out while pregnant is beneficial to both you and
baby. Not only can it reduce back pain, promote healthy weight gain
during pregnancy, and strengthen your heart and blood vessels, but it
may also decrease your risk of gestational diabetes, preeclampsia, and
cesarean delivery, according to ACOG. (PS: Did you know this birthing
method even existed?) Still, that doesn't mean you should go
balls-to-the-wall and adopt a routine you've never tried before. In
fact, that's the exact opposite of what you should do, and these are
some ways to tell whether you're pushing too much. But if you're healthy
and your doctor gives you the go-ahead, it's usually safe to continue
regular physical activity. Just use that talk test to help keep you in
line, and maybe leave the heart rate monitor at home.