Hormonal Contraception and Bone

Abstract

Newer progestins possess a strong anti-gonadotropic activity. Combined oral hormonal contraceptives (COCs) containing 15–20 μg EE and a newer progestin suppress the hypothalamic-pituitary-ovarian axis despite the low EE content, so that in adolescents, endogenous oestradiol production is decreased to peri- and postmenopausal levels and reduces bone formation. Therefore, low-dose oral contraceptive use might interfere with normal acquisition of peak bone mass when given early after menarche. Adolescent girls using low-dose COCs (15–20 μg EE daily) have been shown to possess a lower mean gain in bone density and to reach only a subnormal peak bone mass compared to users of 30 μg EE pills or untreated controls. In consequence, COCs containing 15–20 μg EE should be avoided in adolescents before peak bone mass has been acquired. However, this evidence should not lead to the consequence that a safe contraceptive method is refused to young women: in adolescents, 30 μg EE pills are safe for the acquisition of a normal peak bone mass. Combined oral contraception has no adverse impact on BMD when given during adulthood and might prevent the bone loss occurring in perimenopause. Oral contraceptive past use is associated with an increased risk of fracture in adult women if COC intake has been started below the age of 30 years.There is strong evidence from longitudinal data showing that depot medroxyprogesterone acetate (DMPA) compromises BMD in adult current users. If DMPA is administered to adolescent girls, bone formation and peak bone mass are reduced. The decrease in bone density appears to be at least partially reversible in both adult and adolescent women. DMPA has to be reserved for patients where no alternative contraceptive method is possible.For all other hormonal contraceptive methods, good evidence is missing concerning their effect on bone. However, pilot studies suggest in some an adverse effect on peak bone mass.The supply of sufficient calcium, vitamin D through food or with substitutes and proteins is important for the bone health in women of all ages needing contraception.