Updated

Contrary to earlier signs that women on the Pill have a higher risk of heart disease, a new look at the medical literature found no link between heart attacks and the so-called mini-pills.

Such pills, including brands like Micronor and Ovrette, contain the hormone progestin, but not the estrogen of traditional birth control pills. The results also held for other progestin-only birth control products, such as implants and shots.

"I think this is very reassuring that there is no increased risk of heart attack," said Chrisandra Shufelt of the Women's Heart Center at Cedars-Sinai Medical Center, who was not involved in the review.

Millions of women worldwide take progestin-only contraceptives. While combined contraceptives, which blend progestin and estrogen, are more popular, their safety is still a matter of debate, Shufelt said. Two reviews of earlier research, for instance, found roughly twice the risk of heart attack among women on the Pill compared to those not on birth control.

Just two out of a million healthy women in their early 30s actually suffer a heart attack, however, so even doubling that risk still wouldn't amount to much.

Still, women at increased risk of heart disease, such as heavy smokers or those with high blood pressure, might consider switching to mini-pills or another progestin-only product, said Dr. Genevieve Plu-Bureau, who led the review.

"In women without cardiovascular risk factors, I do not think that this switch would be necessary," Plu-Bureau, at the Hotel-Dieu Hospital in Paris, added in an e-mail to Reuters Health.

The new work, published in the Journal of Clinical Endocrinology and Metabolism, is based on results from six previous studies that examined heart attack risk in women on progestin-only birth control.

The studies included more than 1,800 women aged 16 to 44 years on birth control and compared those to women not taking the hormones.

It's the first review to focus on mini-pills, which often cost more than $50 per month, and it does have limitations. For instance, Plu-Bureau said the number of women was small, and her group didn't separate them based on the dose of hormone or the type of progestin they took.