In the Journals Plus

Hormonal contraception may cause bone loss in adolescent girls

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January 11, 2019

Healthy adolescent girls exposed to combined hormonal contraception experienced less bone mineral density accrual at the lumbar spine over 24 months vs. those not exposed to hormonal birth control methods, according to findings from a systematic review and meta-analysis.

Jerilynn C. Prior

“This meta-analysis of prospective, controlled, observational studies of adolescent girls shows significant and clinically important spinal bone loss over 2 years in teens using combined hormonal contraception,” Jerilynn C. Prior, MD, FRCPC, professor of endocrinology and metabolism in the department of medicine at the University of British Columbia and founder and scientific director at the Centre for Menstrual Cycle and Ovulation Research in Vancouver, told Endocrine Today. “Instead of using combined hormonal contraception as the go-to, routine therapy in adolescent girls, we need to use evidence-based and physiological ways to treat cramps, heavy flow, irregular cycles and acne, and nonhormonal methods for contraception.”

Prior and colleagues analyzed data from nine open-label clinical trials and observational, longitudinal studies that included adolescent girls prescribed any combined hormonal birth control (including estrogen and progestin in oral, patch or ring preparation) or no intervention between 2014 and 2018. Included studies were conducted in Brazil, Canada, China and the United States and reported absolute BMD change over 1 and 2 years (measured via DXA). The researchers recorded pooled estimate of absolute change at the lumbar spine BMD site at 12 or 24 months of hormonal contraceptive use, or for a similar duration in control adolescent girls.

Eight studies had 12-month BMD data (n = 1,535) and five had 24-month BMD data (n = 885); all studies scored for low risk of bias.

At 12 months, researchers observed a –0.02 g/cm² weighted mean difference change in absolute spinal BMD for girls exposed to hormonal contraception vs. control adolescent girls (95% CI, –0.05 to –0); however, heterogeneity was high at 96%.

At 24 months, researchers observed a similar change in absolute spinal BMD for girls exposed to hormonal contraception vs. control adolescent girls (weighted mean difference, –0.02 g/cm²; 95% CI, –0.04 to –0.01), with 85% heterogeneity.

In four studies with 12- and 24-month BMD data, researchers found that, among adolescent girls exposed to hormonal contraceptives, the standardized mean difference rose from –0.333 at 12 months (95% CI, –0.675 to 0.009) to –0.832 at 24 months (95% CI, –1.422 to –0.242) compared with control adolescent girls, suggesting ongoing bone loss.

“We need randomized, placebo-controlled trials of combined hormonal contraception in adolescent girls with primary outcomes of changes in bone mineral density, cramps, heavy flow, acne and amenorrhea, including the cycle lengths and ovulatory characteristics of both groups, over 6 months after stopping 1 year of therapy,” Prior said. – by Regina Schaffer

For more information:

Jerilynn C. Prior, MD, FRCPC, can be reached at the University of British Columbia Centre for Menstrual Cycle and Ovulation Research, Room 4111, 2775 Laurel St., Vancouver, BC, Canada, V5Z 1M9; email: jerilynn.prior@ubc.ca.

Disclosure: One of the authors reports she has received a grant from Bayer.