Women who get several months' worth of birth control pills at once are more likely to stick with the contraceptive than those who get a shorter-term supply, a new clinical trial suggests.
As it stands, private and public health insurance plans in the U.S. generally limit how many months' worth of birth control pills can be prescribed at a time. The practice was established years ago, when there were concerns about the Pill causing certain health problems, including high blood pressure.
The idea was that having women make more doctor visits could help in catching any ill effects.
But even now that those concerns have been eased, the restriction on Pill prescriptions remains.
And studies suggest that it's a barrier to women continuing with birth control pills; researchers have found that "running out of pills" is one of the most common reasons women cite for giving up the Pill.
So for the new study, researchers randomly assigned 661 girls and women at a New York City family-planning clinic to receive either 3-month or 7-month supplies of birth control pills.
They found that of women in the latter group, 51 percent were still using their pills 6 months later.
That compared with only 35 percent of women receiving 3 months' worth of pills at a time, the researchers report in the journal Obstetrics & Gynecology.
It may not sound surprising that a longer-lasting pill supply would improve adherence.
"It does make sense," said lead researcher Dr. Katharine O'Connell White, of Tufts University School of Medicine and Baystate Medical Center in Springfield, Massachusetts.
"But you need to do the research to confirm it," White added -- especially, she noted, if health insurers are going to change their coverage policies.
If longer-lasting Pill supplies boost women's adherence, the hope is that it would translate into fewer unintended pregnancies. This study did not look at that.
But a study published earlier this year suggested such a benefit.
Researchers found that of low-income women in California's "Medi-Cal" program, those given a year's supply of birth control pills were less likely to have an unplanned pregnancy. For every 1,000 women in the study, 10 in the year-supply group became pregnant within a year, versus 30 in the group of women who got 1- to 3-month supplies.
White acknowledged that the 51-percent adherence rate in this study still falls short. "The supply of pills is not the only factor in whether women continue," she said.
But the effects of the longer-term supply are still meaningful, according to White.
"We have not found a lot of things that work" as far as women's adherence to birth control pills, she said. "This actually has the potential for a big impact."
As for the other reasons that women stop using the Pill, side effects appear to be a key one.
Of the 287 women in this study who stopped taking the Pill and could be questioned about it, 83 said they stopped because of side effects.
Another 58 women said they stopped because they ran out of pills, and 54 said they were no longer sexually active.
White suggested that if a woman has symptoms she thinks are attributable to the Pill, she talk with her health provider. For one, White noted, the problem may not actually be a Pill side effect. And if it is likely to be a side effect, such as bleeding between periods, then it may be manageable -- by changing the dose, for instance.
Other potential side effects of the Pill include headache, breast tenderness and nausea -- all of which often go away after a few months of use, according to the American College of Obstetricians and Gynecologists.
As for costs, a month's supply of birth control pills runs anywhere from $15 to $50. Paying for a year's supply would obviously be a bigger initial cost, and some women may not use their whole year's worth.
But those costs, White noted, are much lower than the cost of a pregnancy.