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Vitamin D deficiency and fetal growth
L Brunvand1, E Quigstad, P Urdal
1Department of Pediatrics, Ullevål University Hospital, Oslo, Norway.
Insights
Maternal vitamin D deficiency impacts fetal growth. Higher maternal ionized calcium and lower parathyroid hormone levels correlate with increased infant length, suggesting a role in calcium homeostasis.
Area of Science:
- Obstetrics and Gynecology
- Endocrinology
- Nutritional Science
Background:
- Vitamin D deficiency in pregnancy is linked to reduced fetal growth.
- Previous studies found no direct link between newborn weight and maternal 25-hydroxyvitamin D3 (calcidiol) levels.
- The precise mechanisms by which vitamin D deficiency affects fetal development remain unclear.
Purpose of the Study:
- To investigate the relationship between maternal serum calcium and parathyroid hormone (PTH) levels and fetal growth in vitamin D-deficient pregnant women.
- To explore the role of maternal calcium homeostasis in mediating the effects of vitamin D deficiency on fetal development.
Main Methods:
- A study involving 30 Pakistani women at delivery, excluding those with chronic diseases or complicated pregnancies.
- Maternal blood samples were collected 1-4 hours postpartum for analysis of 25-hydroxyvitamin D3, ionized calcium, and PTH.
- Infant anthropometric data, including crown-heel length, were recorded.
Main Results:
- Nearly all participants (29/30) exhibited low serum 25-hydroxyvitamin D3 levels.
- A significant positive correlation was observed between maternal serum ionized calcium and infant crown-heel length (rho = 0.65, P = 0.002).
- Maternal serum PTH levels showed a significant inverse correlation with infant crown-heel length (rho = -0.47, P = 0.01).
Conclusions:
- Vitamin D deficiency during pregnancy may impair fetal growth.
- Maternal calcium homeostasis, influenced by calcium and PTH levels, appears to be a key factor in this process.
- The findings suggest that vitamin D deficiency affects fetal growth primarily through its impact on maternal calcium regulation.
Abstract:
Vitamin D deficiency in pregnancy has been associated with decreased fetal growth, but previous studies have found no direct relation between the weight of the new-born child and the maternal serum level of 25-hydroxyvitamin D3 (calcidiol). The aim of this study was to evaluate the relation between maternal serum calcium and parathyroid hormone with reduced fetal growth in vitamin D deficient pregnant women. Thirty Pakistani women were included in the study at delivery. Only mothers without known chronic diseases who delivered vaginally after an uncomplicated pregnancy were included. Anthropometric data were recorded, and blood samples were drawn from the mothers 1-4 h after delivery. Nearly all (29/30) the Pakistani women had low (< 30 nmol/l) serum levels of 25-hydroxyvitamin D3. Thirteen of the mothers had high serum parathyroid hormone (PTH) levels (> 5.5 pmol/l). The median (range) level of ionised calcium in serum was 1.23 (1.15-1.28) nmol/l. A positive correlation was found between the level of ionised calcium in maternal serum and the crown-heel length of the infant (Spearman's rho = 0.65, P = 0.002, n = 20). The maternal serum PTH was related inversely to the crown-heel length (Spearman's rho = -0.47, P = 0.01, n = 30). No confounding effect of gestational age, sex of the infant, maternal height and body mass index (BMI) was found. The study indicates that vitamin D deficiency affects fetal growth through an effect on maternal calcium homeostasis.