Abstract

Pregnancy is a common physiological event that affects bone mass and may cause development of osteoporosis or fragility fractures. Only a few longitudinal studies have been performed covering the complete reproductive cycle of any size and showing changes in bone mineral density  (BMD). We describe a healthy woman (aged 35 years) with reversible bone loss associated with pregnancy. We measured the BMD of the lumbar spine and femoral neck by dual-energy X-ray absorptiometry in this woman one year and three years before conception and then again two  months, one year and two years after pregnancy. Although the BMD measurements were performed within another clinical study, we found interesting changes worth presenting. In this case, bone mineral density before pregnancy was normal and remained at the same level over three years, whereas after delivery there was a significant decline in BMD and osteopenia was diagnosed. Comparison of the T-scores revealed a decrease of 0.5SD in the total hip region, while loss at the lumbar spine was 1.1SD. The changes did not involve any signs or symptoms and the performed tests did not yield clinically significant findings. During pregnancy the patient passed routine followup. Blood calcium, measured in the 33nd week, was normal. The markers of bone metabolism were not measured.
We can confirm that the observed bone loss was due to pregnancy as bone mineral density in  this patient was normal and remained at the same level over three years. She did not pass lactation after delivery. There were no risk factors for bone loss during pregnancy, or other inciting causes. The patient was healthy, without clinically significant diseases before, during or after pregnancy. She followed a healthy lifestyle with normal physical activity and received a balanced and calcium-rich diet with calcium and vitamin D supplementation during pregnancy. She did not take medications and had no other identifiable cause for bone loss.
Conclusion. It is mostly believed that bone loss during pregnancy is caused by some diseases, medications, prolonged breastfeeding or other risk factors. Yet bone loss is common also in normal healthy women in the course of pregnancy. All pregnant women, even those without risk factors for osteoporosis, need special care and follow-up for their bone health.