A prospective study of the effects of oral and injectable contraception on bone mineral density

Bone densitometry in premenopausal women: synthesis and review

Bone loss prior to menopause is being increasingly identified in women. Clearly, low bone mineral density (BMD) is a significant risk factor for fracture in the estrogen-deficient female postmenopause. The significance of low bone density prior to menopause needs to be addressed. Low bone density in the premenopausal female may reflect attainment of a lower peak bone mass. It may also be secondary to progressive bone loss following achievement of peak bone density. The etiology of low bone density in the premenopausal female needs to be clarified with meticulous exclusion of secondary causes of bone loss. Menstrual status is an important determinant of peak bone mass as well as the development of bone loss in women prior to the onset of menopause. Subclinical decreases in circulating gonadal steroids may be associated with a lower peak bone mass as well as progressive bone loss in otherwise reproductively normal women. Elevations of follicle-stimulating hormone (FSH) of greater than 20 miu/L are associated with evidence of increased bone turnover marker activity and correlate with progressive bone loss in perimenopausal women. This transitional period requires further study with respect to the magnitude of bone loss experienced and the potential benefits of antiresorptive therapy. Detailed assessment of menstrual status is necessary in the evaluation of low bone density in premenopausal women. The majority of the cross-sectional and longitudinal studies completed evaluating BMD in the premenopausal years suggest that minimal bone loss does occur prior to menopause after attainment of peak bone mass. The magnitude of premenopausal bone loss, however, is controversial and may be site-dependent. More rapid rates of bone loss are seen in the transitional period beginning 2-3 yr prior to the onset of menopause. Prospective data are needed to understand further the relationship between BMD and fracture in the premenopausal period. Women with steroid-induced bone loss as well as other secondary causes of osteoporosis respond to antiresorptive therapy with documented improvements in BMD. Biomarkers can identify perimenopausal women with increased bone turnover. Lifestyle modification can improve BMD in the pre- and the perimenopausal period. Antiresorptive therapy has not been evaluated in pre- or perimenopausal women with low BMD in the absence of secondary causes of osteoporosis. As new treatment options are evaluated and become available, biomarker assessment may be of value in identifying women at risk of fracture.

Injectable hormone contraception and bone density: results from a prospective study

BACKGROUND

Depot medroxyprogesterone acetate (DMPA) injectable contraception may decrease bone density and increase the risk for osteoporosis in later life. Prospective data are scarce, especially of the effects of DMPA discontinuation on bone.

METHODS

Between 1994 and 1999, we conducted a population-based prospective cohort study among women enrollees of a Washington State health maintenance organization. We enrolled 457 nonpregnant women, ages 18-39 years (183 DMPA users and 274 non-users). Bone density was measured by dual-energy x-ray absorptiometry every 6 months for 3 years.

RESULTS

Bone density decreased notably among DMPA-exposed women at the spine (adjusted mean bone density was -0.0053 gm/cm for DMPA users compared with +0.0023 gm/cm for non-users for each 6-month interval) and total hip (-0.0060 compared with -0.0002 gm/cm ). This represents an annualized mean rate of change at the spine of -0.87% compared with +0.40% and, at the hip, -1.12% compared with -0.05%. Discontinuers of this method (N = 110) showed sizable increases in bone density over comparison women (for each 6-month interval, adjusted mean spine bone density was +0.0067 gm/cm compared with +0.0023 gm/cm, respectively; adjusted mean hip bone density was +0.0035 compared with -0.0002 gm/cm ). Estimated annualized mean rates of change were +1.41% compared with +0.40% [corrected] at the spine and +1.03% [corrected] compared with -0.05% at the hip. After 30 months, mean bone density for discontinuers was similar to that of non-users.

CONCLUSIONS

In this study, DMPA use was strongly associated with bone density loss. Substantial postdiscontinuation recovery of bone provides evidence that the effects may be largely reversible.

Bone mineral density at various anatomic bone sites in women receiving combined oral contraceptives and depot-medroxyprogesterone acetate for contraception

The association between users of combined oral contraceptives and depot-medroxyprogesterone acetate (DMPA) for contraception and bone mineral density (BMD) has been controversial because of variations among studies. Like other studies, this cross-sectional study compares BMD in users of combined oral contraceptives and DMPA with that in nonusers. Unlike previous studies, we defined long-term use as >2 years, and we measured more bone sites than previous studies including lumbar spines, femurs, and forearms. The study group consisted of 59 women aged 30 years to 34 years who had been using combined oral contraceptives for 57.36 +/- 27.02 months with a minimum period of 24 months, 34 women of the same age who had been using DMPA as contraceptive for 55.76 +/- 35.31 months, and 62 women of the same age who had not used any steroid hormonal contraceptives for more than 6 months. BMD was measured by dual energy photon absorptiometer at lumbar spine 2-4, neck of femur, Ward's triangle of femur, greater trochanter of femur, ultradistal radius, and distal ulnar, respectively. Age, body mass index, and lifestyles of both groups were matched with nonusers. Mean BMD at lumbar spine (L2-4) in the DMPA users was significantly lower than in the controls (1.031 +/- 0.090 vs. 1.096 +/- 0.116, p = 0.007). There were no significant differences in BMD values at bone sites other than lumbar spine between DMPA users and the controls. There were no significant differences in BMD values at all bone sites between combined oral contraceptives users and the controls. We conclude that combined oral contraceptives are not associated with changes in values of BMD, while DMPA is associated with decreased BMD only at lumbar spine. We comment that steroid hormonal contraceptives are safe to use for long-term contraception regarding bone mass effects.

Forearm bone density in long-term users of oral combined contraceptives and depot medroxyprogesterone acetate

OBJECTIVE

To compare the bone mineral density of users of combined oral contraceptives (OC) or depot medroxyprogesterone acetate (depot-MPA) with women who have never used a hormonal contraceptive method.

DESIGN

Cross-sectional study.

SETTING

Academic tertiary-care hospital.

PATIENT(S)

A total of 189 women, aged 30 to 34 years old, were allocated to three groups: 63 who had used OC for at least 2 years; 63 who had used depot-MPA for at least 2 years; and 63 control women who had never used hormonal contraceptives.

INTERVENTION(S)

Each woman's bone mineral density (BMD) was evaluated at the distal and ultradistal section of the radius of the nondominant forearm by the use of single x-ray absorptiometry.

MAIN OUTCOME MEASURE(S)

We obtained BMD measurements for each participant.

RESULT(S)

Independent of the period of use and the section of the forearm studied, we found no difference in BMD for OC or depot-MPA users when compared to women who had never used hormonal contraceptive methods. In addition, BMD was similar between OC users and depot-MPA users. The multiple linear regression analysis showed that the variables associated with BMD were weight, number of pregnancies, and the woman's occupation.

CONCLUSION(S)

Women aged 30 to 34 years who have used OC or depot-MPA have similar BMD as control women. These findings suggest that the use of OC or depot-MPA does not affect the BMD of women in this age group.