NIH: Elevated blood pressure before conception may increase the chances
for pregnancy loss, according to an analysis by researchers at the
National Institutes of Health. The authors conclude that lifestyle
changes to keep blood pressure under control could potentially reduce
the risk of loss. The study appears in Hypertension. The analysis found that for every 10 mmHg increase in diastolic blood
pressure (pressure when the heart is resting between beats), there was
an 18-percent-higher risk for pregnancy loss among the study population.
Millimeter of mercury, or mmHg, is the unit of measure used for blood
pressure. The researchers also found a 17 percent increase in pregnancy
loss for every 10 mmHg increase in mean arterial pressure, a measure of
the average pressure in the arteries during full heart beat cycles. The
study was conducted by researchers at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
“Elevated blood pressure is linked to heart disease, stroke, and
kidney disease” said the study’s senior author, Enrique Schisterman,
Ph.D., chief of the Epidemiology Branch at NICHD. “Our findings suggest
that attaining a healthy blood pressure before pregnancy could not only
have benefits later in life, but also reduce the chances for pregnancy
loss.”
NICHD researchers analyzed data collected as part of the Effects of Aspirin in Gestation and Reproduction
(EAGeR) trial, which sought to determine if daily low-dose aspirin (81
milligrams) could prevent miscarriage in women who had a history of
pregnancy loss.
The EAGeR trial enrolled more than 1,200 women ages 18 to 40 years
and took blood pressure readings before the women were pregnant and
again in the fourth week of pregnancy. Average diastolic blood pressure
for the women in the study was 72.5 mmHg; normal blood pressure in
adults is a diastolic reading of below 80 mmHg. The authors began to see
an increase in pregnancy loss among women who had a diastolic reading
above 80 mmHg (approximately 25 percent of the participants). None of
the women in the study had stage II high blood pressure (above 90 mmHg
in systolic high blood pressure or above 140 mmHg in systolic blood
pressure).
The researchers note that the study does not prove that elevated
blood pressure causes pregnancy loss. It is possible that another,
yet-to-be identified factor could account for the findings. They added,
however, that the relationship between preconception blood pressure and
pregnancy loss remained the same when they statistically accounted for
other factors that could increase pregnancy loss, such as increasing
maternal age, higher body mass index or smoking.
“Our results suggest that further research could help determine if
treating elevated blood pressure and other health risks before
conception improves pregnancy outcomes,” said the study’s first author,
Carrie Nobles, Ph.D., a postdoctoral fellow in the NICHD Epidemiology
Branch.
About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD):
NICHD conducts and supports research in the United States
and throughout the world on fetal, infant and child development;
maternal, child and family health; reproductive biology and population
issues; and medical rehabilitation. For more information, visit https://www.nichd.nih.gov.
About the National Institutes of Health (NIH):
NIH, the nation's medical research agency, includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and Human
Services. NIH is the primary federal agency conducting and supporting
basic, clinical, and translational medical research, and is
investigating the causes, treatments, and cures for both common and rare
diseases. For more information about NIH and its programs, visit www.nih.gov.