A "perfect" contraceptive may not be possible, but women today might be able to find the next best thing.
In the last six months, the Food and Drug Administration has approved an oral contraceptive that eliminates a monthly menstrual period, and it can prevent mood swings and other side effects.
It also has approved two others that feature shorter periods. And it's expected to sign off on a yearlong oral contraceptive and a simpler version of a contraceptive implant.
Of course, there's no long-term data on the new methods - and they aren't for everyone - but doctors consider this new generation of birth control to be less risky and more sophisticated than the decades-old predecessors.
"Anytime there is a new method, there will be some women who say, 'Oh, thank goodness, there is something for me,"' says Dr. Carolyn Westhoff, medical director of family-planning clinics at New York Presbyterian/Columbia University Medical Center. "It's not that different than trying to find the best pair of jeans to fit your body."
That's not an easy thing to do. But what seems to fit many women is curtailing or eliminating menstruation altogether.
Two brands of birth control pills, both approved this year and now available, feature shorter periods than the usual five to seven days. The products - Loestrin 24 Fe and Yaz - provide 24 days of active pills, forms of the hormones estrogen and progestin, followed by four days of placebo pills.
And in May, the FDA approved Seasonique, a slightly different version of Seasonale, which was approved in 2003 as the first continuous-use oral contraceptive. With Seasonale, which will become available in September, women take the active pills for 84 days followed by seven days of inactive pills to allow for a period. Seasonique, however, substitutes low-dose estrogen in place of the placebo pills so that a woman's hormone levels don't crash during the off week.
Finally, the FDA is considering an application to approve the first yearlong oral contraceptive. Lybrel contains only active pills without any break for a period.
"For the last 40 years of the pill, one thing we've done is we've lowered the dose for improved safety," Westhoff says. "But all along we were sticking to this original recipe of 21 days of hormones and seven days of placebo."
Pass on the pain
The shift to continuous-use oral contraceptives acknowledges a little known fact: Women don't need to have periods.
Although early pills were associated with high levels of hormones and a risk of blood clots, the level of hormones in birth control pills has dropped dramatically in the last two decades. Now, even taking an active pill 365 days a year is not thought to be harmful, says Dr. David Portman, director of the Columbus Center for Women's Health Research in Columbus, Ohio.
Nor does the extended-use regimen appear to interfere with fertility. In a study of 187 women presented in May at a meeting of the American College of Obstetricians and Gynecologists, researchers reported that almost 99 percent of the women had a period or became pregnant within 90 days of stopping the medication.
"There is no lingering effect of the medication in the body because it is metabolized very quickly," says Dr. Anne Davis, an assistant professor at Columbia University and lead investigator of the study.
When oral contraceptives were introduced decades ago, the placebo week "was put in there to mimic the natural cycle," she says. "It was done with the idea that the pill would be more acceptable to women. It wasn't done because of safety or effectiveness."
Not for everybody
That's not to say the pills are right for everyone. For those with a shaky memory, the downside of a year-round pill is remembering to take it every day. Women who miss pills may have trouble determining whether they are pregnant without a break from the pill for menstruation.
"You would have to go on other symptoms to know if you're pregnant," Davis says. Oral contraceptive use during early pregnancy is not thought to be linked to birth defects, she says.
However, the effects of taking Lybrel during several months of pregnancy have not been specifically studied. And some health experts caution that there is a lack of data on continuous-use birth control pill regimens.
For women who find daily methods difficult, the first contraceptive implant to emerge since Norplant was removed from the market in 2002 is expected to be approved by the FDA later this year.
That earlier implant consisted of six matchstick-size rods that were placed under the skin of the forearm to release fertility-controlling hormones. But the product was plagued with problems, including the difficulty of inserting and removing the rods.
The new implant, Implanon, consists of a single rod that can prevent pregnancy for three years and is now under FDA review.
Other long-term contraceptives approved in recent years include NuvaRing, which became available in 2001. A small, flexible vaginal ring that releases hormones, it's worn for three weeks then removed for one week. And Mirena, a hormone-releasing intrauterine device, was approved in 2001 and provides five years of protection.
Another long-term contraceptive, the injectable Depo-Provera, was reformulated in 2004 with lower doses of hormones. The newer formulation is injected four times a year under the skin instead of into the muscle, Westhoff says. A weekly method also has found a niche. Ortho Evra, the first transdermal contraceptive patch, was approved in 2001. Each hormone-releasing patch is worn for one week; after three weeks, no patch is worn to allow for a menstrual cycle.
Some of the newer products do carry risks. In November, the FDA changed the labeling for the Ortho Evra patch to warn that the product exposes women to higher levels of estrogen than most birth control pills, which may increase the risk of blood clots. And Depo-Provera has been found to reduce bone density, although the newer formulation is thought to cause less bone loss.