Injectable birth control, menstrual dysfunction, eating disorders predict BMD loss in young women
Young women who use the injectable progestin contraceptive depot medroxyprogesterone acetate, or DMPA, experience menstrual dysfunction or have symptoms of a subclinical eating disorder experienced more bone mineral density loss in the spine and hip over 4 years than women without those risk factors, according to research in Bone.
In a longitudinal study of healthy, physically active college-aged women, researchers also found that modest bone accrual occurred in the absence of risk factors, and that oral contraceptives had no effect on change in BMD.
Jeri W. Nieves
Jeri W. Nieves, PhD, of the Clinical Research Center at Helen Hayes Hospital in Haverstraw, New York, and colleagues analyzed data from 91 female cadets in the U.S. Military Academy at West Point (mean age, 18.4 years; 82% white; mean BMI, 23 kg/m²; mean body fat, 21%). Researchers assessed menstrual function, birth control use and calcium intake via questionnaires; eating disorders were assessed using eating disorder inventory subscales; BMD of the calcaneus, spine and total hip was measured via DXA scan. All cadets took a yearly Army Physical Fitness Test; body fat and BMI were measured annually. Researchers calculated slope of 4-year BMD change at each skeletal site for each participant.
Within the cohort, 50% of women experienced BMD gains in the spine over 4 years; 36% had BMD gains at the hip. Researchers found that the loss of both spine and hip BMD were related to the use of DMPA after adjusting for race, weight change, eating disorder inventory score and baseline BMD. After multivariable adjustment, black women were more likely to experience an increase in hip BMD over 4 years (P = .023), as were women who gained weight (P = .008) and had normal menses (P = .011). Black women were also more likely to experience an increase in spine BMD (P = .035), as were women who had an eating disorder inventory score in the normal range (P = .04) and normal menses (P = .001).
“Physical activity has the capacity to increase BMD and modify bone structure and geometry by increasing mechanical loads to bones that stimulate osteogenic responses,” the researchers wrote. “The fact that even in the physically active women we still found bone loss related to high [eating disorder inventory] scores, weight loss, menstrual irregularity or DMPA use indicates a need for further education and intervention in these areas in young women.” – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.