Relationship Between Maternal Bone Biomarkers and Fetal Adiposity Through Normal Pregnancy

Abstract

Purpose: To examine the association of maternal bone markers [sclerostin, soluble receptor activator of nuclear factor-κB ligand (sRANKL), osteocalcin, 25-hydroxyvitamin D3] with fetal intra-abdominal and subcutaneous adipose tissue deposition and birthweight during normal pregnancy.

Methods: One hundred pregnant women (aged 30.4 ± 5.6 years, mean ± SD) with prepregnancy body mass index = 24.1 ± 4.6 kg/m2 were seen prospectively during each trimester. At each visit they were submitted to anthropometric measurements, a fasting blood sampling, a 75-g oral glucose tolerance test, and a fetal ultrasonogram. At birth, neonates had birth weight measurement.

Results: In the second trimester, maternal sclerostin concentrations correlated positively with fetal abdominal circumference and birth weight; maternal sRANKL concentrations correlated positively with fetal abdominal subcutaneous fat thickness, sagittal abdominal diameter, and abdominal circumference. Fetuses born to mothers with greater (>254 ng/mL), compared to fetuses born to mothers with lower (≤254ng/mL), sRANKL concentrations had greater abdominal circumference, sagittal diameter, and abdominal subcutaneous fat thickness. Maternal serum sclerostin concentrations were the best positive predictors of birth weight. In the third trimester maternal sclerostin concentrations correlated positively with fetal sagittal abdominal diameter; maternal sRANKL concentrations positively correlated with fetal abdominal circumference and fetal abdominal sagittal diameter.

Conclusions: Maternal bone markers sclerostin and sRANKL may relate to fetal intra-abdominal adipose tissue deposition through as yet unknown direct or indirect mechanisms, thus contributing to birthweight.

Keywords: birthweight; fetal intra-abdominal fat; pregnancy; sRANKL; sclerostin.