A reader asked me to take a look at this study (abstract here) and see if it reaches a valid set of conclusions. The study was conducted in California among ~80,000 women who receive birth control pills paid for by the state as part of a program for low income women. Previously, women in the program have received a 1 or 3 months supply of birth control at a time, and then have to go in to the clinic in order to receive a refill. In the study, a portion of these women were given a full year’s supply instead of one or three months, and state medical records were then used to see if this resulted in a change in the rate of unplanned pregnancy and abortion among the women who received a full year supply of birth control.
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.”
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. [source]