In a population with concurrent high prevalences of IUGR, vitamin D deficiency, and dietary calcium deficits, this study aimed to estimate the associations between maternal PTH concentrations and newborn size at birth, to identify potentially modifiable nutritional and endocrine factors associated with maternal PTH, and to assess the direct and indirect (i.e. PTH-mediated) pathways by which maternal PTH and its regulators may influence fetal growth. Here, PTH is linked to vitamin D deficiency.