Parathyroid hormone (PTH) values, Vitamin D status, Fetal bone Growth and Placental RANK‐L expression among Pregnant Adolescents

Pregnant adolescents may be at risk for suboptimal vitamin D status and bone loss across pregnancy. RANK/RANK‐L/OPG interactions are integral to osteoclast activity and alterations in RANK‐L expression may be associated with the critical balance between maternal bone loss and fetal bone growth during pregnancy. To assess these issues, vitamin D status (25‐hydroxyvitamin D) was monitored in pregnant adolescents ( < 18 years old) and their neonates in relation to longitudinal measures of fetal femur and humerus growth, and placental expression of RANK‐L. Fetal femur and humerus length was obtained by sonogram three times across gestation to assess fetal bone growth. Blood samples were collected from each adolescent mid‐gestation and at parturition when cord blood and placental tissue were also obtained. In 25 adolescents studied to date, expression of soluble RANK‐L in the placenta approached significance as a predictor of fetal bone growth (p=.066). At delivery, 71% (n=17) of teens had elevated PTH (>46 pg/mL). 41% (n=43) of teens and 63% of neonates (n=38), had suboptimal vitamin D levels ( < 20 ng/mL). Recruitment and analyses are on‐going and additional relationships between serum osteoprotegerin (OPG), maternal bone loss, and fetal bone accrual across pregnancy will be explored. Grant Funding Source USDA Grant No: 2008‐01857