THURSDAY, Feb. 13, 2014 (HealthDay News) -- The increased risk
of having a stroke or other blood-clotting problem might continue
longer after a woman gives birth than previously believed,
according to a new study.
"Historically, six weeks was the accepted period," said study researcher Dr. Hooman Kamel.
"We found the risk of blood clots remained higher than normal for twice as long as previously thought. After 12 weeks, it was no longer significant," said Kamel, an assistant professor in the Weill Cornell Medical College department of neurology and the Feil Family Brain and Mind Research Institute.
Even though the elevated risk continues for longer than
previously believed, Kamel stressed that the overall risk is still
The study was published online Feb. 13 in the
New England Journal of Medicine. Kamel, who is also a
neurologist at NewYork-Presbyterian Hospital, is presenting the
study Thursday at an American Stroke Association meeting in San
Kamel and his team looked at medical information from nearly 1.7
million women in California giving birth to their first child. The
women delivered between early 2005 and mid-2010. Through the first
year and a half after delivery, about 1,000 of the women had
clotting problems, including about 250 strokes, 50 heart attacks
and more than 700 cases of venous thromboembolisms (clots in the
legs or lungs).
"Just like prior studies, we found the risk of these types of blood clots during the first six weeks after birth was [more than] 10 times higher than normal," Kamel said.
In the seven to 12 weeks after delivery, the risk dropped to
twice the normal rate, he said. After 12 weeks, the risk was the
same as when the woman was not pregnant.
Doctors monitor women for blood clots during pregnancy because
the blood clots more easily at that time, according to the American
Society of Hematology.
The risk of clotting problems during pregnancy is increased in
women who are obese or genetically predisposed to clots, according
to the society. The risk also increases in women who are inactive,
on prolonged bed rest or take long trips by plane or car.
Kamel said smokers and women with chronic high blood pressure
are also at increased risk.
Doctors give high-risk women low-dose blood thinners for six
weeks after delivery to reduce their risk, Kamel said. Future
research should focus on whether 12 weeks would be a better
timeframe for the drugs, he said.
The study was funded by the U.S. National Institute of
Neurological Disorders and Stroke.
The findings suggest that both doctors and pregnant women should
have a heightened awareness of the potential blood clot risk longer
than the traditional six-week period, said Dr. Burton Rochelson,
chief of maternal fetal medicine at North Shore LIJ Health System
in Manhasset, N.Y.
Rochelson reviewed the findings but did not participate in the
study. He, too, emphasized that although the increased risk was
found to persist, the absolute risk is small. "Even though the risk
increases in that seven to 12 weeks, you are still talking about
very few people relative to the total number," he said.
Since the events are serious, however, "even a small number is
undesirable," he said.
One study limitation, Rochelson said, is that the researchers
combined all the blood-clotting problems. In future studies, he
said, researchers should consider looking separately at the risks
of heart attacks, strokes and blood clots in the legs and
Women should be aware of the warning signs of a blood clot
problem, Kamel said. These include chest pain or pressure;
difficulty breathing; pain or swelling in one leg; sudden and
severe headache; or a sudden change in consciousness, speech,
balance, strength or sensation on one side of the body.
To learn more about blood clots and pregnancy, visit the
American Society of Hematology.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
Copyright © EBSCO Publishing. All rights reserved.