While previous studies have associated birth control-related weight gain with a higher BMI, Berenson's study suggests that a lower BMI under 30 is more predictive. "The amount of DMPA administered to a woman does not change based on weight, as occurs with some medications," Berenson said. "The drug may be more concentrated in the tissue of a woman with a BMI under 30 and may contribute to excessive weight gain, but more research is needed."
The biological mechanism of DMPA-related weight gain is still unknown, but researchers note that possible mechanisms include glucocorticoid-like activity, how the body breaks down simple carbohydrates such as glucose, and DMPA-associated interference with insulin action. Previous findings seem to argue against the theory that weight gain could be due to the drug's perceived effects on increased caloric intake and decreased energy expenditure, but ongoing research is needed to confirm or discount varying possible explanations.
DMPA is an injected contraceptive administered to patients every three months. According to the American College of Obstetricians and Gynecologists, more than 2 million American women use DMPA, including approximately 400,000 teens. DMPA is relatively inexpensive compared with some other forms of birth control, has a low failure rate and doesn't need to be administered daily, which contributes to the contraceptive's popularity.
This study builds upon UTMB research released earlier this year that found DMPA users gain significant weight not seen among women using oral or nonhormonal contraception. The study was supported by the National Institute of Child Health and Human Development. Yen-Chi L. Le, of UTMB's department of obstetrics and gynecology, and Mahbubur Rahman, of UTMB's Center for Interdisciplinary Research in Women's Health, contributed to this research.
|Contact: Kristen Hensley|
University of Texas Medical Branch at Galveston