(NEW YORK) -- The decision to use birth control is one that most women face at some point, and today many options exist to help women control whether and when they get pregnant. But some of these approaches may carry risks -- it has long been known that certain kinds of birth control can increase the risk of clots in the legs and lungs.
Now, a new study by Danish researchers suggests that hormonal contraception also increases the risk of heart attacks and stroke in women.
The overall risk remains low, but the new study, published Wednesday in the New England Journal of Medicine, indicates that these hormonal approaches do indeed boost stroke and heart attack risk in the women who take them.
In the study, researchers looked at more than 1.6 million women over a period of 15 years and tracked all the contraceptive measures they took -- including the pill, the vaginal ring, intrauterine device, subcutaneous implants, skin patches and intramuscular injections, commonly called the "Depo shot."
Women who had already had a stroke or heart attack or who had a clotting disorder were not included in the study, and the researchers also accounted for women who smoked -- a known risk factor for some types of clots.
What they found was that although the absolute risk of stroke and heart attacks associated with the use of contraception was low, the chances of these problems occurring was 0.9 to 1.7 times higher on estrogen at a low dose. These risks increased to a factor of 1.3 to 2.3 when a higher dose of estrogen was used.
Not all birth control methods contain estrogen, and it was found that progestin-only products, such as the IUD, did not significantly change the risk of having a heart attack or stroke.
While many women taking hormonal birth control may worry about the prospect of having a heart attack or stroke, Dr. Lauren Streicher at Northwestern Memorial Hospital in Chicago said that "pregnancy is far more likely to cause an MI or stroke than hormonal contraception." This, she said, is because hormone levels naturally change in a woman's body during pregnancy, increasing the risk of clots.
Dr. Jacques Moritz, director of gynecology at St. Luke's-Roosevelt Hospital in New York, agreed, adding that the normal risks associated with pregnancy must be considered alongside those of taking hormonal contraception.
"You throw in ectopic pregnancy and its associated complications and the pill looks good," he said.
Doctors agree that women should talk with their physicians to carefully consider all risks before starting any medication -- and birth control is no exception.
Copyright 2012 ABC News Radio