More women in the United States are dying from pregnancy-related causes, and the majority of those deaths could be prevented, according to new data from the Centers for Disease Control and Prevention. The report finds that about 700 U.S. women die from complications of pregnancy or childbirth each year. Of those cases, 3 out of 5 are considered preventable.

These deaths can occur during pregnancy, at delivery, or up to a year after. From 2011 to 2015, about a third of such cases happened during pregnancy, a third occurred at delivery or in the week after, and another third happened one week to one year postpartum.

While death from pregnancy is very rare in advanced countries today, the rate in the U.S. has been rising for decades and is much higher than in other nations like Canada and Britain.

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"An American mom today is 50% more likely to die in childbirth than her own mother was," Dr. Neel Shah, a Harvard Medical School obstetrician, told the Associated Press.

Heart disease and stroke were the leading cause of death in the study, responsible for more than 1 in 3 deaths overall. Obstetric emergencies, like severe bleeding and amniotic fluid embolism (when amniotic fluid enters the woman's bloodstream), caused the most deaths at delivery.

In the week following delivery, high blood pressure, severe bleeding, and infection were the most common causes of death. One week to one year postpartum, cardiomyopathy — or weakened heart muscles —caused the most deaths.

The numbers are especially bleak for certain groups. Black and American Indian/Alaska Native women were about three times as likely to die from a pregnancy-related cause as white women.

U.S. women fare worse during pregnancy and childbirth

Research has long shown that the U.S. lags behind other developed nations in terms of maternal care.

A 2018 report published by the Commonwealth Fund compares the experiences of women in the U.S. and 10 other high-income countries, including Norway, Sweden, the U.K., Germany, Switzerland, France, the Netherlands, Canada, Australia and New Zealand.

The findings shed light on some grim realities for American women. In the United States, 14 women die during pregnancy per 100,000 live births. Compare that to Sweden, the country with the lowest maternal mortality rate in the study, where the number is just 4 per 100,000 live births.

The authors of that report noted "women in the U.S. have the highest rate of maternal mortality because of complications from pregnancy or childbirth, as well as among the highest rates of caesarean sections."

Additionally, more than one-third of women in the United States reported skipping needed medical care because of costs — a far more common occurrence in the U.S. than the other countries in the study. American women were less likely to rate their quality of care as "excellent" or "very good," compared to women elsewhere.

What can be done to save women's lives?

Tennis star Serena Williams called attention to the problem last year when she wrote about the life-threatening complications she experienced after the C-section birth of her daughter, Olympia. She suffered a pulmonary embolism, or blood clot in her lung, which "sparked a slew of health complications that I am lucky to have survived."

Experts say access to quality care during and after pregnancy is essential for preventing pregnancy-related deaths.

The CDC calls on health care providers to help patients manage chronic conditions and communicate warning signs of complications. It also calls on states and communities to take steps to improve access to housing and transportation, which affect health outcomes, and to "develop policies to ensure high-risk women are delivered at hospitals with specialized health care providers and equipment."

For their part, women and their families should be aware of warning signs of potentially serious complications, and communicate about their recent pregnancy history any time they receive medical care in the year after delivery.

According to the March of Dimes, warning signs women should look out for include:

Chest pain

Trouble breathing

Heavy bleeding

Severe headache

Extreme pain

"Ensuring quality care for mothers throughout their pregnancies and postpartum should be among our nation's highest priorities," CDC Director Robert R. Redfield, M.D., said in a statement. "Though most pregnancies progress safely, I urge the public health community to increase awareness with all expectant and new mothers about the signs of serious pregnancy complications and the need for preventative care that can and does save lives."