UCSF study shows increased contraceptive supply decreases unintended pregnancy rates

University of California - San FranciscoFeb 24 2011

Rates of unintended pregnancies and abortions decrease significantly when women receive a one-year supply of oral contraceptives, instead of being prescribed one- or three-month supplies, a UCSF study shows.

Researchers observed a 30 percent reduction in the odds of pregnancy and a 46 percent decrease in the odds of an abortion in women given a one-year supply of birth control pills at a clinic versus women who received the standard prescriptions for one - or three-month supplies.

The researchers speculate that a larger supply of oral contraceptive pills may allow more consistent use, since women need to make fewer visits to a clinic or pharmacy for their next supply.

"Women need to have contraceptives on hand so that their use is as automatic as using safety devices in cars, " said Diana Greene Foster, PhD, lead author and associate professor in the UCSF Department of Obstetrics, Gynecology and Reproductive Sciences. "Providing one cycle of oral contraceptives at a time is similar to asking people to visit a clinic or pharmacy to renew their seatbelts each month."

Foster also is director of research for Advancing New Standards in Reproductive Health, part of the UCSF Bixby Center for Global Reproductive Health. Her study's findings appear online today http://journals.lww.com/greenjournal/Abstract/2011/03000/Number_of_Oral_Contraceptive_Pill_Packages.8.aspx in the journal Obstetrics and Gynecology.

The researchers linked 84,401 women who received oral contraceptives in January 2006 through Family PACT (Planning, Access, Care, Treatment), a California family planning program, to Medi-Cal data showing pregnancies and births in 2006. Through Family PACT, some family planning clinics are able to dispense a one-year supply of pills on-site.

Oral contraceptive pills are the most commonly used method of reversible contraception in the United States, the team states. While highly effective when used correctly (three pregnancies per 1,000 women in the first year of use), approximately half of women regularly miss one or more pills per cycle, a practice associated with a much higher pregnancy rate (80 pregnancies per 1,000 women in the first year of use), according to the team.

The findings of this study have implications for women using oral contraceptives across the country. Most oral contraceptive users in the United States get fewer than four packs at a time; nearly half need to return every month for resupply, according to a 2010 study published in Contraception.

Making oral contraceptive pills more accessible may reduce the incidence of unintended pregnancy and abortion, while saving taxpayers' dollars, the researchers state. If the 65,000 women in the analysis who received either one or three packs of pills at a time had experienced the same pregnancy and abortion rates as women who received a one-year supply, almost 1,300 publicly funded pregnancies and 300 abortions would have been averted, according to the team.

"The evidence indicates that health plans and public health programs may avoid paying for costly unintended pregnancies by increasing dispensing limits on oral contraceptives," said Foster. "Improving access to contraceptive methods reduces the need for abortion and helps women to plan their pregnancies."

Co-authors are Denis Hulett, Mary Bradsberry, Phillip Darney, MD, MSc, and Michael Policar, MD, MPH, all with the Bixby Center for Global Reproductive Health, UCSF Department of Obstetrics, Gynecology, and Reproductive Sciences, and San Francisco General Hospital.