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Heart attacks on the rise in pregnant women, study finds

The risk of having a heart attack during pregnancy or during the two months after delivery is increasing in the United States. A new 12-year study led by the NYU School of Medicine found that the risk of suffering a heart attack among pregnant American women rose 25 percent from 2002 to 2014.

Of the women who had heart attacks, 4.5 percent died. The results, published in the journal Mayo Clinic Proceedings, did not surprise Dr. Holly Andersen, a cardiologist at New York Presbyterian Weill Cornell Medical Center.

"When you look at the national data, heart disease deaths in young women have been increasing since the year 2000 so it makes sense heart attacks are happening more in our pregnant women, as well," Andersen told "CBS This Morning" Wednesday. She was not involved in the research.

The study authors say a number of factors are likely contributing to these numbers, including the trend of women having children later in life, since heart attack risk rises with age overall and especially during pregnancy.

Pregnancy itself is also a strain on the heart. "A pregnant woman is significantly more likely to have a heart attack than non-pregnant women because you have a bigger blood volume, you gain weight, your heart rate increases, your blood pressure increases," Andersen explains. "And right at the time of delivery you have to prevent bleeding so your body clamps down and you become more likely to form blood clots. All of this predisposes you to heart attacks."

What's more, the risk factors for heart disease continue to increase in the United States. "High blood pressure, high cholesterol, diabetes are all higher in our younger women, and I think stress probably plays a factor, as well," Andersen said.

Andersen emphasized that there are steps women can take to reduce their risk of heart attack before, during, and after pregnancy.

"I would like all women to know that heart disease is the number one cause of death for women and it's increasing in young women and it's a very preventable disease," she said. "So know your risk factors and work to decrease them… Don't smoke. Get your sugar levels, cholesterol levels, and blood pressure checked and work to get them better. Eat right, exercise, try to get a good night's sleep, and talk to your doctor about your risk factors."

For the study, the researchers examined data on nearly 50 million births recorded in hospitals, where the majority of deliveries in the United States take place. They found that 1,061 heart attacks happened during labor and delivery, and 2,390 heart attacks occurred during the recovery period after birth. Another 922 women were hospitalized for a heart attack before birth.

The study's senior investigator, Dr. Sripal Bangalore, an interventional cardiologist at NYU, notes that although the absolute numbers of heart attacks and heart attack deaths in pregnant women remain low, the relatively high death rate comes despite advances in treating heart attacks.

"Our analysis, the largest review in a decade, serves as an important reminder of how stressful pregnancy can be on the female body and heart, causing a lot of physiological changes, and potentially unmasking risk factors that can lead to heart attack," Bangalore, an associate professor in the Department of Medicine at NYU Langone Health, said in a statement.

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