USC Researchers Urge Caution In Prescribing Progestin-Only Oral Contraceptives For High-Risk Women
LOS ANGELES, August 12, 1998 -- Women who develop diabetes during pregnancy face an increased risk of later developing type-2 diabetes. Now, USC researchers say that using the mini-pill -- progestin-only birth control pills -- may put these women at an even higher risk of developing the chronic form of the disease.
"It appears that progestin-only oral contraceptives increase risk by nearly three-fold and should not be widely prescribed in this group of women," says Siri Kjos, M.D., associate professor of obstetrics and gynecology at the University of Southern California School of Medicine.
That caution, however, is tempered by good news, Kjos (pronounced KEY-hos) says. "The most important finding is that low-dose combination oral contraceptives appear to be a relatively safe method of contraception for these very high-risk women." The combination birth control pills are the most commonly used ones and contain a mix of estrogen and progestin.
Kjos and colleagues report their results in the August 12 issue of the Journal of the American Medical Association.
In the study, USC researchers followed 904 Latina women who had developed gestational diabetes mellitus (GDM) during a recent pregnancy, but whose ability to process sugars had returned to normal after delivery.
During their initial post-partum visits to the High Risk Family Planning Clinic at LAC+USC Women's and Children's Hospital, about half chose to use hormonal oral contraceptives and half chose a non-hormonal contraceptives. Of the women opting to take birth control pills, 383 were prescribed low-dose combination birth control pills and the 78 women who were breast-feeding received the progestin-only contraceptives.
For women who wish to breast-feed and take hormonal contraceptives, doctors usually prescribe progestin-only oral contraceptives because they do not interfere with milk production. In the present study, women were switched to the low-dose combination pills once they stopped breast-feeding.
The research team found that 169 women developed chronic diabetes during the study and that the risk was influenced by the type of contraception they had used. Of the women taking the progestin-only mini-pill, an average of 26.5% per year developed type-2 diabetes, compared to a rate of only 8.7% per year of women using non-hormonal contraceptives and 11.7% per year of those choosing a low-dose combination oral contraceptive.
"We found that the longer a woman used the progestin-only oral contraceptives, the higher her risk of later getting diabetes," Kjos says.
Type-2 or adult-onset diabetes strikes more than 14 million Americans, according to estimates from the American Medical Association. Since it can be asymptomatic in its early stages, many are only diagnosed with a blood test. Most develop the disease in middle age. Obesity, having a close relative with the disease and being a member of certain ethnic groups (including African-American, Latino and Native American) are known risk factors. Without treatment, type-2 diabetes can lead to serious complications including heart disease, stroke, nerve disease, vision problems and kidney failure. Lifestyle changes (such as dietary changes and increasing exercise) and oral medications prove effective in controlling diabetes for most people.
"Family planning is extremely important for women with a history of gestational diabetes," says study co-author Thomas Buchanan, M.D., USC associate professor of medicine and obstetrics and gynecology. In earlier studies, the same team had found that women with a history of GDM who have a subsequent pregnancy face two-to-three-fold the risk of later developing type-2 diabetes. Contraception is also important for the health of the woman's future children -- if a woman gets pregnant and has uncontrolled diabetes, her fetus faces an increased risk of birth defects, and she is more likely to miscarry or suffer other potentially fatal complications.
"When we started the study we were more interested in finding out whether oral contraceptives in general were safe in these women," says Ruth Peters, Sc.D., USC professor of preventive medicine who also helped lead the study. "We found that it's OK to use oral contraceptives even if you have had gestational diabetes. But if you're breast feeding, and so would be prescribed a progestin-only pill, you may want to choose non-hormonal contraceptives instead," Peters says.
This study was supported in part by grants from the National Institutes of Health and the National Institute of Diabetes and Digestive Kidney Diseases.
Editor's Note: To set up an interview with Dr. Ruth Peters, please call Eva Emerson at 323-442-2830.