Bone-sparing properties of oral contraceptives

Am J Obstet Gynecol. 1996 Jan;174(1 Pt 1):15-20. doi: 10.1016/s0002-9378(96)70366-6.

Abstract

Postmenopausal osteoporosis is a major health care problem that affects 20 million women in the United States and accounts for > 1 million fractures per year. Hormone replacement therapy is effective for reducing bone loss in the postmenopausal women. However, intervention before menopause may delay or prevent the decline in bone mass that begins between ages 30 and 40 years. The effects of oral contraceptives on bone mass have been investigated, and a positive association between oral contraceptive use and bone mass that is directly related to the duration of oral contraceptive use was observed. The effects of oral contraceptives on bone mass may be related to the specific formation. The effect of estrogens is dose related, and the optimal dose appears to be 25 to 35 micrograms of ethinyl estradiol or its equivalent. Results from several studies show that norethindrone has a positive effect on bone mass. An oral contraceptive may offer optimal birth control for the older premenopausal woman who currently uses other forms of birth control.

PIP: A review of the research literature on the effects of oral contraceptives (OCs) on bone mass suggests that premenopausal OC use may exert as beneficial an effect on preserving bone mass as hormone replacement therapy does on stabilizing bone mass loss in menopausal and postmenopausal women. Of the 12 studies reported in the literature, 9 found some positive correlation between these two variables in postmenopausal and/or premenopausal and perimenopausal women. The most significant increases in bone mineral density were recorded among women who had used OCs for more than 3 years. One study found that bone mineral density increased by 1% for each year of OC use. The three studies that failed to confirm any differences between OC users and nonusers in bone mineral density could be criticized methodologically for their focus on subjects with less than 5 years of pill use. Clinical studies have indicated that an OC containing 20-35 mcg/day of ethinyl estradiol in combination with the progestin norethindrone produces the optimal bone-sparing effect in premenopausal women while minimizing the risk of venous thrombosis. Since osteoporosis affects close to 20 million women and results in over 1 million bone fractures each year, this is yet another noncontraceptive benefit of OC use.

Publication types

  • Review

MeSH terms

  • Adult
  • Contraceptives, Oral / therapeutic use*
  • Ethinyl Estradiol / administration & dosage
  • Ethinyl Estradiol / therapeutic use
  • Female
  • Humans
  • Menopause
  • Norethindrone / administration & dosage
  • Norethindrone / therapeutic use
  • Osteoporosis, Postmenopausal / prevention & control*
  • Premenopause

Substances

  • Contraceptives, Oral
  • Ethinyl Estradiol
  • Norethindrone