Differential effects on bone density of progestogen-only methods for contraception in premenopausal women

Adolescents: at increased risk for osteoporosis?

Perhaps the most important factor in the primary prevention of osteoporosis is the attainment of an optimal peak bone during adolescence. In addition to endogenous factors, such as genetic and ethnic background, environmental factors such as dietary habits, physical activity, and sex hormone therapy, influence the accretion of bone mass during this critical period of skeletal growth. First, calcium dietary intake in adolescents is generally well less than the current recommended RDA of 1200 mg/day. Multiple studies of children and adolescents have demonstrated increases in bone mass with dietary calcium supplementation. Second, regarding physical activity, the overall impression is that a moderate amount of particularly weight-bearing exercise has a positive impact on bone. There appears, however, to be a threshold of intensity of physical activity over which a negative impact on bone occurs, particularly when the exercise is of an anaerobic nature or occurring in very thin, amenorrheic participants. Third, previous research suggests that the various forms of hormonal contraception exert differing effects on bone mass in adolescents, with levonorgestrel implants and combined oral contraceptives may be associated with a more positive effect on bone mass compared with that observed with depot medroxyprogesterone acetate. From a clinical perspective, approaches to optimizing peak bone mass in adolescents would include increasing calcium intake, whether in the form of dairy products, fortified foods, or supplements as well as encouraging participation at a moderate level, in weight-bearing exercise. Last, in adolescents with extensive risk factors and predicted long duration of use, subdermal implants or combined oral contraceptives may be the optimal hormonal methods of birth control.

A prospective study on the effects of depot medroxyprogesterone acetate on trabecular and cortical bone after attainment of peak bone mass

OBJECTIVE

To study the annual change of bone mass in women aged 30-45 years being treated with depot medroxyprogesterone acetate (DMPA) in order to evaluate whether the bone mass depends on the duration of DMPA use or the oestradiol level.

DESIGN

Prospective longitudinal study over an interval of 12 months.

SETTING

A family planning centre of a university hospital.

PATIENTS

Thirty-six current users of DMPA.

INTERVENTIONS

Injection of 150 mg DMPA every 12 weeks.

MEASUREMENTS

Bone mass was measured at the distal radius by peripheral quantitative computed tomography (reproducibility 0.3%).

RESULTS

Mean annual changes (SD) in trabecular and cortical bone mass were 0.06 (1.6%) [P = 0.8] and -0.26% (0.6) [P < 0.04]. The decrease in cortical bone mass was not significant because the changes were within the precision error of the method used for the measurements. Duration of DMPA use and oestradiol levels were not associated to the bone parameters.

CONCLUSION

We did not find a negative impact of DMPA on the bone mass of premenopausal women aged 30-45 years.

Menstrual cycle, contraception, and performance

Although understanding of the unique physiology of the female athlete has increased, there are still many questions to be answered. Endogenous and exogenous female sex steroids have been shown to influence various cardiovascular, respiratory, and metabolic parameters, but these changes probably have minimal impact on the ability of most recreational athletes to participate in and enjoy their sport. Statistically significant data may or may not have clinical or performance relevance. By the same token, a statistically nonsignificant change may mean the difference between first and second place to an elite athlete. For an athlete concerned about maximizing performance, individual variability in menstrual cycle changes to various performance parameters must be considered. It is difficult to predict how accurately controlled laboratory findings from a study population apply to an individual competitor on the playing field. Athletes taking OCs for contraception or for menstrual cycle control may be able to minimize any potential side effects and performance influences by taking the lower dose triphasic pills and the newer progestins. For women with menstrual dysfunction, OCs may provide a predictable hormonal milieu for training and competition. Further scientific study is needed using large-scale, prospective, randomized clinical trials on trained athletes and accurate hormonal measurements to determine the phase of the menstrual cycle to determine short- and long-term effects of cycle phase and OCs in exercising women. As more questions continue to be answered, physicians and sport scientists will be better able to guide women not only to maximize their performance but to ensure lifelong good health.

Evidence that treatment with monophasic oral contraceptive formulations containing ethinylestradiol plus gestodene reduces bone resorption in young women

The aim of the study was to evaluate if a pill containing the same dose of the same type of progestin compound (gestodene, GES, 75 microg) but different doses of ethinylestradiol (EE2) (20 or 30 microg) differently influences specific markers of bone resorption (urinary levels of pyridinoline (PYR) and dexoxypyridinoline (D-PYR)). During the 12 months of the study a significant decrease of urinary levels of PYR and D-PYR was found in 2 groups of young post-adolescent women taking the pills with 20 and 30 microg of EE2 in comparison with control women (subjects of the same age group with normal menstrual cycle who did not use contraception). In women taking pills with 20 or 30 microg EE2, the levels of sex hormone-binding globulin (SHBG) significantly increased during treatment in comparison with baseline, whereas in the same time period no changes occurred in control women. These findings suggest that similar to the pill containing 30 microg EE2, the lower dosage of the EE2 pill (20 microg) is also capable of reducing bone resorption. Twenty and 30 microg EE2 pills exert the same biological estrogenic effect. In fact, SHBG levels significantly increased with both pills. However, an additional effect of the progestin compound that could act directly on progestin or estrogen receptors of bone cannot be excluded. Since contraception with a pill containing the lowest estrogen dose is associated with the lowest incidence of side effects, these findings further suggest a pill containing 20 microg EE2 for young post-adolescent women would be the best choice.

Bone mineral density during long-term use of the progestagen contraceptive implant Implanon compared to a non-hormonal method of contraception

An open, prospective, comparative study was done in healthy women, aged between 18 and 40 years, to study the effects of long-term etonogestrel treatment on bone mineral density (BMD). The control group used a non-hormone-medicated intrauterine device (IUD). The BMD was measured using a dual energy X-ray absorptiometry instrument. Measurements included the lumbar spine (L(2)-L(4)), the proximal femur (femoral neck, Ward's triangle, trochanter) and distal radius. The period of treatment was 2 years and 44 women in the Implanon group and 29 in the IUD group provided data. Groups were comparable at baseline with respect to age, weight, body mass index, BMD and 17beta-oestradiol status. Changes from baseline in BMD in the Implanon group were not essentially different from those in the IUD group. There was no relationship between 17beta-oestradiol concentrations and changes in BMD in this study population. The results of the present study indicate that Implanon((R)) can safely be used in young women who have not yet achieved their peak bone mass.

Norplant((R)) implants and progesterone vaginal rings do not affect maternal bone turnover and density during lactation and after weaning

Bone density and turnover was assessed in a longitudinal study of healthy lactating women who initiated use of Norplant((R)) implants (NOR, n = 29), progesterone vaginal rings (PVR, n = 28) or Copper T 380A intrauterine devices (T-Cu, n = 51, control group) around day 60 postpartum. Bone density, serum calcium, phosphorus, alkaline phosphatases, parathyroid hormone (PTH), follicle stimulating hormone (FSH), oestradiol and prolactin, and urinary hydroxyproline and creatinine were measured at postpartum months 1 (PM1), and 12 (PM12) and 6 or 12 months after weaning; at month 6 postpartum (PM6) serum and urine tests alone were performed. Baseline characteristics and lactation performance were similar between groups. Biochemical markers of bone turnover were higher at PM1, PM6 and PM12 than after weaning, with no differences between groups. Bone density in the lumbar spine (L2-L4) and femoral neck at PM1 and PM12 ( approximately 1.11 g/cm(2)) was similar in three groups. Lumbar spine values were found to be lower in lactating women than those present in non-lactating women, but increased after weaning to similar values. The two progestin-only contraceptives studied appear to have no deleterious effect upon bone density and metabolism in healthy lactating women.

Effects of levonorgestrel-releasing subdermal contraceptive implants on bone density and bone metabolism

A prospective, randomized clinical trial observed the effects of Norplant long-term contraceptive implants and domestic implants similar to Norplant on bone mineral density and bone metabolism in female acceptors for 1 year. Bone mineral density (BMD) and bone mineral content (BMC) of lumbar 2-4 and proximal femur of 61 normal women of child-bearing age were measured by dual energy x-ray absorptiometry (DEXA) before and 12 months after implants insertion in both groups. BMD and BMC of lumbar 2-4 in both groups 12 months after implant insertion significantly increased (p < 0.01); with an average increase of 2.40% and 3.34%, respectively in the Norplant implant group, and 2.75% and 4.47%, respectively in the domestic implant group. Urine hydroxyproline and creatinine ratio (Hop/Cr) in the domestic implant group significantly decreased (p < 0.01). There was no significant differences in the effects on BMD and BMC of lumbar spine and femur and on bone metabolism between the two groups of contraceptive implants (p > 0.05). Levonorgestrel releasing contraceptive subdermal implants were not deleterious to the skeleton in women of child-bearing age. There was no significant effect on achieving maximum bone mass in young women.

Forearm bone density in users of Depo-Provera as a contraceptive method

OBJECTIVE

To determine the influence of depot medroxyprogesterone acetate (MPA) on bone mineral density when used as a contraceptive method.

DESIGN

Cross-sectional study.

SETTING

Academic tertiary-care hospital.

PATIENT(S)

Fifty premenopausal women who had used depot MPA as a contraceptive method for > or =1 year and 50 women who had never used hormonal contraceptive methods.

INTERVENTION(S)

Bone mineral density was evaluated at the midshaft and at the distal radius of the nondominant forearm using single x-ray absorptiometry.

MAIN OUTCOME MEASURE(S)

Bone mineral density.

RESULT(S)

Bone mineral density at the midshaft of the forearm was lower in depot MPA users than in women who had never used hormonal contraceptive methods, but the difference was not statistically significant. At the distal portion, bone mineral density was significantly lower in the study group. The duration of depot MPA use was not related to bone mineral density.

CONCLUSION(S)

Women > or =35 years of age presented with a lower bone mineral density only at the distal portion of the forearm after the use of depot MPA for > or =1 year. However, this decrease was not related to the duration of depot MPA use. It is not possible to conclude that women who use depot MPA are at risk of osteoporosis.

Effects of hormonal contraceptives on bone mineral density

The clinical research to date on the effects of 3 types of hormonal contraceptives, i.e. depot medroxyprogesterone acetate ('Depo-Provera'), levonorgestrel subdermal implants ('Norplant'), and oral contraceptives, on bone mineral density in premenopausal women is reviewed. The large variance in results across studies for each method is in part due to differences in research design, techniques for measuring bone mineral density, age of the study participants and type of oral contraceptive preparation. However, the balance of the evidence leans toward a positive effect of oral contraceptives on bone mineral density in women of all age. On the other hand, few observations have yet been published on the effects of the new progestin oral contraceptives on bone mineral density. The few extant data suggest a positive impact of levonorgestrel subdermal implants on bone mineral density in women of all ages. Although the findings are preliminary, it appears that depot medroxyprogesterone acetate may exert a negative effect on bone mineral density. More specifically, caution should be exercised in prescribing long term depot medroxyprogesterone acetate (e.g. > 5 years) especially in young adolescents (e.g. < 16 years old) who may not have yet reached peak bone mass.

Bone density among long-term users of medroxyprogesterone acetate as a contraceptive

The bone density (BD) of 72 women using depot-medroxyprogesterone acetate (DMPA) for at least 1 year was compared with that of 64 women who were not users of hormonal contraceptives. The BD of lumbar spine, femoral neck, Ward's triangle, and trochanter was measured by dual energy X-ray absorptiometry (DEXA-LUNAR DPX). Estradiol (E2) concentrations were measured by radioimmunoassay (RIA). The mean age of DMPA users and nonusers was 31.8 and 31.1 years, respectively. Mean E, was 55.7 pg/mL for users and 149.9 pg/mL for controls (p < 0.001). The BD was significantly lower for DMPA users than for controls in all sites (p < 0.01). In addition, young adult T-scores in the lumbar spine were significantly lower among DMPA users than in controls (p < 0.01). Differences were maintained in a subsample of 47 women per group paired by age and body mass index (BMI). Multiple regression analysis showed that older age, lower BMI, and longer amenorrhea were associated with lower BD in the femoral neck, whereas lower BMI and use of DMPA were associated with lower BD in the lumbar spine.

Bone density in long term users of depot medroxyprogesterone acetate

OBJECTIVE

To identify any adverse effect on bone density in long term users of depot medroxyprogesterone acetate (DMPA) for contraception.

DESIGN

Cross-sectional measurement of bone density in users with amenorrhoea of more than one year or any woman using DMPA for more than five years.

SETTING

Community Family Planning Clinics in Portsmouth and Manchester.

POPULATION

One hundred and eighty-five women aged 17-52 years (mean 33.3 years) who had used DMPA for between 1 and 16 years and were attending the clinics for further injections, between August 1994 and August 1996.

METHODS

Dual energy X-ray measurement of bone density of femoral neck and lumbar spine, and venous blood sample taken just prior to the next injection of DMPA.

MAIN OUTCOME MEASURES

Bone density of femoral neck and lumbar spine and serum oestradiol in relationship to years of DMPA use and duration of amenorrhoea.

RESULTS

Most women (n=153) had serum oestradiol levels < 150 pmol/l. Despite this, the mean bone density of the lumbar spine compared with the population mean for women aged 20-59 years gave a Z score (95% CI) of -0.332 (-0.510 to -0.154). There was no significant difference in the mean density of the femoral neck from the normal population mean.

CONCLUSION

Despite amenorrhoea and low serum oestradiol, this sample of long term DMPA users had bone density only minimally below the normal population mean. We therefore found no clinically important adverse effect on bone density and therefore no reason to recommend bone conserving measures, such as add-back oestrogen.

Norplant consensus statement and background review

This review has highlighted the attributes of a very important new method of contraception. The signatories to this document agree that, with the provision of appropriate information and instruction for the user, Norplant is a good contraceptive choice to be made available worldwide in family planning programs that have the resources for appropriate training and counseling. The signatories to this document are acting in their own personal capacity and not as representatives of any particular organization.

Oral contraceptives and bone metabolism

In women, the bone metabolism is markedly influenced by gonadal steroids and by their fluctuations. Indeed, estrogens influence bone metabolism by influencing endocrine and paracrine functions involved in bone remodelling. In normally cycling women, the administration of oral contraceptives does not increase bone mineral density and does not induce deleterious effects on bone. In women with ovulatory disturbances, bone turnover is increased and bone mineral density is lower than in normally cycling women. In these cases, administration of oral contraceptives is capable of blocking increased bone loss and of restoring a normal bone mineral density. Similarly, in women treated with gonadotropin releasing hormone (GnRH) analogs, the concomitant administration of oral contraceptives completely antagonizes GnRH analog-induced bone loss. The progestogenic component of oral contraceptives seems to contribute to the protective effect of estrogens on bone. Oral contraceptives are safe for bone maintenance in normal adult women, and are indeed indicated to prevent postmenopausal osteoporosis in women with ovulatory disturbances.

Bone mineral density during long-term treatment with Norplant implants and depot medroxyprogesterone acetate. A cross-sectional study of Thai women

This cross-sectional study compares bone mineral density (BMD) in long-term Norplant implants and depot medroxyprogesterone acetate (DMPA) users. The objectives of this study were to evaluate and compare the bone mineral density between women using these contraceptives. Forty-one current users of Norplant implants and 50 DMPA users participated in the study. The BMD was measured by dual energy x-ray absorptiometry in the nondominant distal and ultradistal forearm. Serum estradiol was measured by microparticle enzyme immunoassay technique. The demographic characteristics were similar in both groups. The mean durations +/- SD of DMPA and Norplant implants were 59.14 +/- 30.73 and 31.1 +/- 11.2 months, respectively. The BMD of long-term Norplant implant and DMPA users was similar. The serum estradiol in the Norplant implant group was significantly higher than in DMPA users. However, the serum estradiol level in DMPA users ranged into normal for the follicular phase, which is higher than for postmenopausal women. This study suggests that two long-acting progestogen contraceptives do not differ with respect to their impact on BMD in long-term users.

Bone mineral density in long-term depot medroxyprogesterone acetate acceptors

The study of bone density in long-term DMPA users is reported. The aims were to study and compare bone density in long-term DMPA users with intrauterine device (IUD) users. Fifty current users of DMPA with a minimum 36 months previous use were compared to 50 current IUD users as control. The bone mineral density was measured by dual energy x-ray absorptiometry (DEXA) at the non-dominant distal and ultradistal forearm. Serum estradiol was measured by microparticle enzyme immunoassay technique in both groups. Age, income, weight, height, BMI, and parity of both groups were matched. The mean bone mineral density of distal forearm in DMPA and IUD users was 0.48 +/- 0.05 g/cm2 in both groups. The mean bone mineral density of ultradistal forearm was 0.38 +/- 0.06 g/cm2 in DMPA users and 0.4 +/- 0.05 g/cm2 in IUD users. No differences in mean bone mineral density of distal and ultradistal forearm between DMPA and IUD users was demonstrated (95% CI -0.02, 0.02 and -0.04, 0.001, respectively). However, the serum estradiol levels were significantly different between DMPA and IUD users (95% CI -122, -68.1). From this study, it is suggested that long-term DMPA use should not have any adverse effect on bone density even if it reduces serum estradiol.

Effects on bone mineral density of low-dosed oral contraceptives compared to and combined with physical activity

A cross-sectional study was designed to examine the influence of exercise compared to and in combination with low-dosed oral contraceptives (OCs) on bone mineral density (BMD). One hundred twenty-eight women (20 to 35 years of age) were assigned to four groups with respect to the years of exercise and OC intake. Influence factors were determined by a detailed questionnaire and interview. BMD for L2-4 and the femoral neck was assessed by DXA. The highest BMD values were found in the group of women characterized by long-term exercise (9.45 +/- 4.32 yr) and short use of OC (1.6 +/- 1.69 yr). No beneficial effect of exercise on BMD was found in the group with a long exercise period (10.4 +/- 4.14 yr) and long-term intake of OC (8.2 +/- 4.14 yr). Differences in mean BMD values between the two groups were significant in all regions assessed (p < 0.05). No differences in mean BMD were found in the groups with short-term exercise but long or brief histories of OC. The question arises as to whether active women taking low-dosed OC at an earlier age will develop an adequate BMD.

A prospective comparison of bone density in adolescent girls receiving depot medroxyprogesterone acetate (Depo-Provera), levonorgestrel (Norplant), or oral contraceptives

OBJECTIVE

To examine bone density among adolescents receiving different forms of hormonal contraception along with that of control subjects.

METHODS

Baseline and 1-year measures of lumbar vertebral bone density were obtained in girls receiving depot medroxyprogesterone acetate (Depo-Provera) (n = 15), levonorgestrel (Norplant) (n = 7), or oral contraceptives (n = 9) and in girls receiving no hormonal treatment (n = 17). In a subsample of Depo-Provera users (n = 8), Norplant users (n = 3), and control subjects (n = 4), bone density measurements were repeated after 2 years. Bone density was measured by dual-energy x-ray absorptiometry.

RESULTS

Body mass indexes, level of pubertal development, substance use, and reproductive histories were not significantly different among the groups. More black girls were represented in the initial Depo-Provera group (p < 0.02), girls in the Norplant group exercised more hours per week (p < 0.02), and control subjects were older (p < 0.01) than those in the other groups. These variables did not significantly affect bone density results. After 1 year, bone density decreased 1.5% in Depo-Provera users, compared with increases of 2.5% in Norplant users, 1.5% in oral contraceptive users, and 2.9% control subjects (p < 0.02). After 2 years, bone density increased a total of 9.3% in Norplant users and 9.5% in control subjects but decreased a total of 3.1% in Depo-Provera users (p < 0.0001).

CONCLUSION

These data suggest that Depo-Provera may, at least temporarily, suppress the expected skeletal bone mineralization in adolescents, whereas Norplant and oral contraceptives are associated with the expected increase in bone density in this population.

Effects of progesterone on serum levels of IGF-1 and on femur IGF-1 mRNA in ovariectomized rats

Local and systemic insulin-like growth factors (IGFs) may be involved in the regulation of bone formation by sex hormones. The present studies describe the in vivo effects of estradiol, progesterone, or both on IGF-1 mRNA abundance in bone, serum IGF-1 levels, and bone formation. Rats were sham-operated (SHAM) or ovariectomized (OVX) at 12 weeks of age and used a week later in three experiments. First, OVX rats were treated with vehicle, estradiol, and/or medroxyprogesterone (MPA) for 3 weeks, and bone formation was assessed in the tibial metaphysis. Second, OVX rats were treated in the same manner and serum IGF-1 levels measured. Third, OVX rats were treated with an injection of vehicle, estradiol, and/or progesterone, and 24 h later, levels of IGF-1 mRNA in the femur were analyzed. The mineralized surface, mineral opposition rate, and bone formation rate (BFR) were higher in OVX than in SHAM rats. The BFR was decreased in estrogen-treated but increased in MPA-treated rats compared with vehicle-treated OVX rats. Circulating levels of IGF-1 were higher in OVX than in SHAM rats but were not affected by sex hormones in a 3-week experiment, whereas these levels were not different among groups in a 24-h experiment. Northern analysis detected 7.5 and 0.8 kb IGF-1 mRNA transcripts. The abundance of IGF-1 mRNA was higher in OVX than in SHAM rats. IGF-1 transcripts 7.5 and 0.8 kb were decreased by 72 and 29%, respectively, in estrogen-treated and increased by 44 and 43%, respectively, in progesterone-treated rats compared with vehicle-treated OVX rats. We conclude that in the short term, estrogen lowers and progesterone raises bone IGF-1 mRNA and these changes are followed by coordinated changes in bone formation rate.