The Relationship between First Trimester 25-Hydroxyvitamin D3 Levels and Second Trimester Femur Length and their Effects on Birth Weight and Length at Birth

Abstract

Vitamin D is important for fetal development because of its important role during cell proliferation, differentiation, and maturation processes [1,2], also vitamin D is important for placental function, calcium homeostasis, and bone mineralization, which are all important determinants for fetal growth and development [3,4]. Primary source of vitamin D is the exposure to sunlight. Sedentary indoor lifestyles, obesity, and avoiding sunlight each contributes to increased vitamin D deficiency. A pregnant woman needs a daily intake of vitamin D of 800–1000 IU, but the actual need varies according to ethnicity, nutritional factors, and sunlight exposure [5]. Vitamin D deficiency in pregnant women is a great public health problem because of its potential effects on the maternal obstetric outcomes and offspring development [6,7] where vitamin D deficiency may affect early organogenesis and subsequently affect later health and disease [8]. Vitamin D deficiency during pregnancy has been associated with increased risk of adverse obstetric outcomes including increased risk of gestational diabetes, pre-eclampsia, threatened preterm birth, cesarean section, bacterial vaginosis [9-11], also may have adverse effects on fetal development and growth include increase risk of preterm birth and fetal growth restriction resulting in low birthweight and small for-gestational-age neonates [12,13]. It has also been shown that intrauterine bone hypo mineralization is associated with vitamin D deficiency and then a reason for congenital rickets, craniotabes, and osteopenia [14]. 25hydroxy vitamin D is the major storage form of vitamin D in the human, so it can be measured in blood to determine the overall vitamin D status [15], it is the best measure of vitamin D status in human [16]. The main goal of our study was to assess the relationship between maternal circulating 25-hydroxyvitamin D3 [25(OH)D3] concentration and second trimester femur length, infant birthweight and length at birth.