Combined Oral Contraceptives Increase Bone Mineral Density in Women

Cristina Laguna Benetti-Pinto, MD, PhD

Continuous combined oral contraceptives are associated with increased bone mineral density in women with premature ovarian insufficiency compared to low-dose hormone therapy.

Cristina Laguna Benetti-Pinto, MD, PhD, and a team of investigators aimed to evaluate whether combined oral contraceptives could be used as hormone therapy to preserve bone mineral density in women with premature ovarian insufficiency. The team found continuous combined oral contraceptives were a viable option for such therapy in women with premature ovarian insufficiency because it resulted in the least amount of bone mass loss.

"The results of this study support the use of combined oral contraceptives taken in a continuous fashion without a pill-free interval as an option for the treatment of women with (premature ovarian insufficiency)—a regimen that may be particularly appealing for women who wish to avoid the chance of pregnancy,” Stephanie Faubion, MD, MBA, medical director of the North American Menopause Society, said in a statement.

Benetti-Pinto and colleagues conducted a retrospective, observational, longitudinal cohort study using data from the medical records of women with a premature ovarian insufficiency diagnosis. They included women with the diagnosis who had undergone 2 or more bone mineral density scans with an interval of 2±1 years between them. A premature ovarian insufficiency diagnosis was based on hormonal imbalance characterized by amenorrhea or menstrual cycles of more than 120 days occurring before 40 years of age, and at least two follicle-stimulating hormone measurements, performed with an interval of 30 days between them, showing serum levels more than 25 IU/L.

After the team evaluated the association between hormone therapy and bone mass variation, they only included women with consistent use of hormone therapy or those without any kind of hormone therapy use during the interval of bone mass density analysis. They excluded women with mobility issues and those who used any medication or had any disease.

The investigators analyzed age at ovarian insufficiency and age at initiation of hormone therapy. At the time of the bone mass density scan, they also collected age, height, weight, body mass index (BMI), type of hormone therapy used, and duration of hormone therapy. Bone mass density was measured at the lumbar spine, femoral neck, and total femur by dual-energy x-ray absorptiometry.

Benetti-Pinto and the team initially evaluated the medical records of 255 women with premature ovarian insufficiency and ultimately selected 119 following the inclusion and exclusion criteria. The investigators evaluated 420 bone mass density scans. The mean age of inclusion was 30.34±9.24 years old, with a mean BMI of 24.4±4.52 kg/m² and mean bone mass density measurements at the lumbar spine (L1-L4), femoral neck, and total femur of .97±.17, .87±.16, and .9±.15 g/cm².

The bone mass density deltas at the lumbar spine and total femur were greater in the combined oral contraceptive group and high-dose hormone therapy groups. For the lumbar spine, the differences between the scans were greater in the combined oral contraceptive group compared to the low-dose hormone therapy group: -.043 (95% CI; -.062 to -.024), untreated: -.056 (-.08 to -.032), and tibolone: -.05 (-.094 to -.006). Total femur decreases and the delta were lower in the low-dose hormone therapy group (-.038; [-.052 to -.024]) compared to combined oral contraceptives.

The study, “Bone mass in women with premature ovarian insufficiency: a comparative study between hormone therapy and combined oral contraceptives,” was published online in Menopause, the journal of The North American Menopause Society.