An observational study reveals that neonatal vitamin D is primarily determined by maternal contributions: implications of a new assay on the roles of vitamin D forms

Abstract

Background: Vitamin D concentrations during pregnancy are measured to diagnose states of insufficiency or deficiency. The aim of this study is to apply accurate assays of vitamin D forms forms compared to neonates (17.9 ± 13.2 vs. 15.9 ± 13.6 ng/mL, p = 0.289) with a ratio of 1:3. The epimer concentrations, which contribute approximately 25% to the total vitamin D levels, were similar in mothers and neonates (4.8 ± 7.8 vs. 4.5 ± 4.7 ng/mL, p = 0.556). No correlation was observed in mothers between the levels of the circulating form (25OHD 3 ) and its active form. Neonatal 25(OH)D 2 was best predicted by maternal characteristics, whereas 25(OH)D 3 was strongly associated to maternal vitamin D forms (R 2 = 0.253 vs. 0.076 and R 2 = 0.109 vs. 0.478, respectively). Maternal characteristics explained 12.2% of the neonatal 25(OH)D, maternal 25(OH)D concentrations explained 32.1%, while epimers contributed an additional 11.9%. Conclusions: By applying a novel highly specific vitamin D assay, the present study is the first to quantify 3-epi-25 (OH)D concentrations in mother -newborn pairs. This accurate assay highlights a considerable proportion of vitamin D exists as epimers and a lack of correlation between the circulating and active forms. These results highlight the need for accurate measurements to appraise vitamin D status. Maternal characteristics and circulating forms of vitamin D, along with their epimers explain 56% of neonate vitamin D concentrations. The roles of active and epimer forms in the maternal -neonatal vitamin D relationship warrant further investigation.

Maternal vitamin D levels during pregnancy and neonatal health: evidence to date and clinical implications

“…For example, some researchers have reported a decrease in 25(OH)D in late pregnancy [Zhang et al 2014], while others [Ritchie et al 1998] did not detect any significant differences in 25(OH)D measured before or during pregnancy, and during lactation. However, maternal 25(OH)D level remains an important parameter that should be assessed during pregnancy because the fetus is totally dependent on the mother for 25(OH)D [Markestad et al 1984;Karras et al 2013]. Interestingly, randomized controlled trials (RCTs) have demonstrated that vitamin D supplementation during pregnancy contribute to increased umbilical cord and neonatal serum 25(OH)D Sablok et al 2015].…”

“…It has been shown that C3-epimer can contribute up to 60% of total 25(OH)D in infants up to 1 year of age. This epimer has been shown also to be elevated, though to a lesser extent, in pregnant women and cord blood (6-10%) [Bailey et al 2013;Karras et al 2013;Ooms et al 2016 …”

Determinants of Postpartum Vitamin D Status in the Caucasian Mother-Offspring Pairs at a Latitude of 52°N: A Cross-Sectional Study

“…In opposition to Crozier's study, we found no association between vitamin D intake from diet and maternal vitamin D status, although only fish consumption, as the richest source of vitamin D, was assessed. Also, no association between diet and vitamin D status in pregnant women has been proved by other authors [23,[28][29][30] . The explanation is a low intake of vitamin D from diet in pregnant women: 52 IU/day in Australia, 144 IU/day in Europe and 228 IU/day in USA, Canada and Japan [31] .…”

Maternal vitamin D status in pregnancy: a critical appraisal of current analytical data on maternal and neonatal outcomes

“…The association between SGa infants and 25(OH)D insufficiency remained significant. 6 a recent meta-analysis by andersen et al 12 also impact on small effect sizes. The other inclusion/ exclusion bias arises from the study sample size.…”