IS LONG-TERM USE OF HORMONAL CONTRACEPTIVES A RISK FACTOR FOR OSTEOPOROSIS ?

Objective : To study the effect of long-term use of different forms of hormonal contraceptives on bone mineral density (BMD)
Design : A prospective study
Setting: Fertility Care Unit, Mansoura University Hospitals.
Subjects and Methods: One hundred healthy women aged 25-49 years who chose long term hormonal contraceptives were recruited in the study. Women had to fulfill a set of inclusion and exclusion criteria. Tlio.sc women were categorized into five groups, each comprised twenty women. All groups were well balanced with respect (o age, height, weight and body mass index. Those who used combined oral contraceptives (group l), Norplanl subdcrmal implants (group 2), Implanon subdermal implants (group 3), injectablc Dcpo-Provera (group 4) and Control group used non-hormonal intrauterine contraceptive device Tcu 380A (group 5). After 3 years of contraceptive use, bone mineral density (BMD) of lumber spine (L2-L4) was measured for all women using dual energy X-ray absorpliomclry (DEXA). BMD measurements (g/cm2) were expressed as Z-scores to assist in the interpretation of BMD results. BMD and Z-scores in different groups were compared using Annova Test with Post Hoc Test (Turkey HSD) for multiple comparisons between groups.
Results: Of 100 women, 9 women were excluded from analysis and a total of 91 women made up the final sample; 18 used combined oral contraceptives (group 1), 19 used Norplant (group 2), 19 used Implanon (group 3), 18 used Depo-Provera (group 4) and 17 used non-hormonal IUD Tcu 380A (group 5). Age, height and body mass index were not significantly different among the groups. Mean BMD at lumbar spine (L2-L4) was 1.205 (group 1), 1.182 (group 2), 1.11 (group 3) 0.842 (group 4) and 1.113 (group 5). There were significant differences in BMD values at lumber spine between different groups. Depo-Provera group was associated with a lower BMD than the other groups whereas the combined oral contraceptive group was associated with a higher BMD. Mean /.-scores were -0.34 (group 1), -0.37 (group 2), -0.5 (group 3), -2.26 (group 4) and -0.5 (group 5). Multiple comparisons by using Post Hoc Tests (turkey HSD) demonstrated that BMD and Z-scores in Depo-Provera users were significantly lower than that of other groups. All women using Depo-Provera experienced osteoporotic changes with a Z-score ranging from -2.02 to -2.4. Conclusion: Depo-Provera was associated with a significantly lower BMD; hence its long term use is a potential risk factor for osteoporosis. Combined oral contraceptives and Norplant were associated with increased BMD while Implanon had no effect. These results have a great importance in cases of medico-legal examination of women who used Depo-Provera for a long duration as a simple trauma may lead to fractures.