Overcoming real-life on "the Pill"

Oral contraceptives boast annual unintended pregnancy rates well below 1 percent - if used correctly and consistently, that is.

But in the not-so-perfect real world, longer lasting ingredients and shorter monthly breaks between active pills could prove useful in bolstering this form of birth control, hints a new study from Germany.

A typical monthly regimen of oral contraceptives includes 21 days of active pills - usually containing a combination of the hormones estrogen and progesterone - and a 7-day break of inactive sugar pills. The intent is to prevent pregnancy by obstructing ovulation, or the release of an egg during a woman's monthly cycle.

"Forgetting the first active pills of a treatment cycle has the biggest impact on contraceptive failure as this time interval may allow the process that leads to ovulation to start," Dr. Jurgen Dinger of the Berlin Center for Epidemiology and Health Research told Reuters Health in an e-mail.

To test whether decreasing the pill-free interval and using hormones with a longer duration of action may help counteract this common problem, Dinger and his colleagues studied more than 52,000 U.S. women who took part in the "International Active Surveillance of Women Taking Oral Contraceptive" study.

The participants' average age was 26 years, and each had started on a new contraceptive. More than 80 percent of the women had previously taken another version of the Pill.

The researchers did not interfere with the choice of oral contraceptive, but rather categorized the women into three groups based on their new hormone regimens: 21 days of 3 milligrams of drospirenone (progesterone) plus 30 micrograms of ethinyl estradiol (estrogen); 24 days of 3 milligrams of drospirenone plus 20 micrograms of ethinyl estradiol, or another regimen.

The 21-day drospirenone regimen is currently sold under the brand name Yasmin and the 24-day regimen, with longer-lasting progesterone, is sold as Yaz. Generic versions are also available. Bayer Schering Pharma, maker of Yasmin, supported the study.

Over the course of 3 years following the women, more than 1,600 became pregnant unintentionally. About 1,400 of these contraceptive failures were due to an imperfect use of the Pill.

Unintended pregnancy rates for the 21-day and 24-day drospirenone regimens were 2.8 percent and 2.1 percent at the end of the first year, respectively, and 5.7 and 4.7 percent after the third year.

Women older than age 30 were significantly less likely than younger women to get pregnant unintentionally. Women with a college education and who had never carried a child were also less likely to become pregnant.

Obese women - who made up nearly a quarter of the U.S. women studied - had about a 50 percent greater risk of contraception failure after accounting for age, education level and whether or not they had prior children.