Globally, pregnant women are at high risk of vitamin D deficiency, which leads to potential problems for their offspring, as the foetus is completely dependent on vitamin D from the mother.
Mounting evidence shows vitamin D-deficient newborns are likely to suffer from poor neurodevelopmental and anthropometric outcomes, with low maternal vitamin D levels confirmed as a risk factor for atypical behaviour for these children in adulthood.
This also results in children being underweight in the first year of life, and the possibility of impaired infant language development and autism-spectrum disorder.
However, previous studies have produced inconsistent results, perhaps due to the brain developing at different times and therefore having different windows of vulnerability, both in the prenatal and postnatal stages.
Furthermore, there are few studies from Asia, and the number of prospective longitudinal studies involving high-quality subjects is limited.
D for development
Based on this, researchers at China's Wenzhou Medical College and Soochow University conducted a study to further evaluate the link between maternal vitamin D levels and neurodevelopment and anthropometry in Chinese newborns.
They recruited 160 women who had delivered 60 healthy full-term infants, following up with them for six months after they had given birth.
Among this cohort were 80 women with vitamin D deficiency, with the other 80 having a vitamin D level of above 50nmol/L.
The researchers subsequently observed among the children a significant inter-group difference in weight, length and / or head circumference at birth, as well as a significant inter-group difference in cognitive development and achievement at six months of age.
Their multivariate analyses found that maternal vitamin D levels below 50nmol/L were independently related to a greater tendency in the children towards a low Bayley mental score at six months old, alongside a low Bayley motor score.
This led them to state: "We observed that maternal vitamin D was associated with infant neurodevelopment and anthropometry."
Causation yet to be proven
They concluded: "There are several limitations in our study. Firstly, it was impossible to prove a causal relationship due to the cross-sectional nature of our design. Secondly, the small sample may affect the stability of the results.
"Despite these limitations, to the best of our knowledge, we observed meaningful relationships between infant development and maternal vitamin D. Future studies that include important co-variates, like parental IQ and large sample sizes, will help clarify conflicting results reported to date among studies."
Source: Journal of Nutritional Science and Vitaminology
"The Relationship between Maternal Serum Vitamin D Levels and Infant Neurodevelopment and Anthropometry: A Prospective Observational Study"
Authors: Mei-Zhu Chi, et al.