Bisphosphonates in patients with autoimmune rheumatic diseases: Can they be used in women of childbearing age?

Autoimmune rheumatic diseases (ARD) are prevalent in women during their childbearing age. For their treatment, high doses of corticosteroid (CS) for long-term periods are often required, increasing the risk of bone loss. According to recent guidelines, bisphosphonates (BP) should be used as first line treatment to prevent CS induced osteoporosis. However, due to their long-term release from bone and their ability to cross the placenta, it has been suggested to avoid BP in women during their fertile years. BP seem to decrease foetus bone length in pregnant animals, but not in humans, at least, when they are administered at therapeutic dosage. BP are embryo toxic in animals when used at high dosage. In a systematic literature review, we found 58 women treated with BP close before or during pregnancy, showing no related congenital malformations. However, the Unit of Clinical and Epidemiological Genetics in University of Padova collected ten cases of women treated with BP during pregnancy, reporting 20% of congenital malformations. Thus, we suggest to avoid BP during pregnancy and caution with their use in fertile women. When they have to be given before pregnancy, specific affinities of the BP have to be considered to plan the washout period beforehand.