Do bone turnover markers change with a steep drop in maternal steroids?

Objectives: To study the changes of bone physiology during last trimester and compare it with immediate postpartum period associated with the sharp drop of pregnancy steroids. Introduction: The maximum transport of calcium and phosphate is at 36 weeks. The sudden drop of sex steroids after delivery could probably lead to a significant change in bone turnover markers. This study was performed to demonstrate if this has an impact on bone turnover markers (BTM). Materials and Methods: Women with a singleton non-complicated pregnancy were recruited from July 29, 2010 for two months to the end of September 2010. A serum level of bone profile, 25 OH vitamin D, and BTM was taken at 35-36 weeks and repeated at postpartum. A paired t-test using SPSS 16 was used to compare the means. Results: Serum bone profile values were comparable between the two groups. Although the mean postpartum serum value of 25-Oh vitamin (28.06 nmol/L) was lower than during pregnancy (35.72 nmol), it did not reach a statistical significance, in this population. A trend of increase in serum osteocalcin postpartum was observed (p = 0.05). Conclusions: This group of women had a high prevalence of vitamin D deficiency; this was not accompanied with changes in BTM; this suggests that a change in the level of steroids play a role that modify the expected interaction between vitamin D and BTM. Larger studies are however needed.