[Effect of hormonal contraception on bone mineral density]

Oral contraceptives are used by numerous women very often throughout a prolonged period of time and more and more frequently early in life, within the first reproductive years. The close relationship between oestrogen metabolism and bone turnover raises the question of the potential bone impact of oral contraceptives containing low dose of ethinyl-oestradiol and especially in adolescent girls. During adulthood, most studies have reported that oral contraceptive pills, even those containing a low dose of ethinyl-oestradiol (20 mug), had neutral, or possibly beneficial, effect on bone health. Use of oral contraceptives within the perimenopausal years also would allow to preventing bone loss, given that all vascular and metabolic contra-indications are respected. However, the skeletal effects of oral contraceptives are a greater concern for adolescent girls. Some data suggest that the use of 20 mug pills may impede the development of peak bone mass, particularly when started within the teen years. The bone impact of other hormonal contraceptive methods appears correlated with the degree of suppression of oestrogen levels. There is no effect of low dose progestagen-only pills or progestagen implants on bone health. On the other hand, administration of depot medroxyprogesterone acetate is associated with significant bone loss at all skeletal sites. However, the loss of bone mass might be reversed after discontinuation of use, especially in younger women. The bone impact of progestin only pills that have a strong antigonadotrophinic activity is not currently evaluated although there is some concern about increased bone loss in case of oestrogen deficiency period of long duration.