Determinants of vitamin D status in pregnant women and neonates

Abstract

OBJECTIVES: Evidence suggests a beneficial effect of vitamin D on perinatal health; however, low vitamin D status is prevalent in pregnant women and neonates. The objective was to determine factors that are associated with vitamin D status of mothers in early pregnancy and neonates. METHODS:The study comprised 1,635 pregnant women from Quebec City and Halifax, Canada, 2002-2010. Vitamin D status was based on the concentration of 25-hydroxy-vitamin D [25(OH)D] determined with a chemiluminescence immunoassay in maternal sera collected at a median of 15 weeks' gestation and in neonatal cord sera at delivery. A questionnaire with information on potential determinants was completed midpregnancy.RESULTS: A total of 44.8% of mothers and 24.4% of neonates had 25(OH)D concentrations <50 nmol/L. Adjusted mean (95% confidence interval) maternal 25(OH)D levels were higher in summer than in winter by 16.1 nmol/L (13.6-18.7), and in those in the highest versus the lowest category of education by 6.1 nmol/L (0.5-11.8), in BMI <25 kg/m 2 versus BMI ≥35 kg/m 2 by 8.2 nmol/L (4.0-12.3), and in the highest versus the lowest physical activity category by up to 9.5 nmol/L (2.9-16.1). Determinants of neonatal 25(OH)D levels were similar but also included maternal age, dairy intake, supplement use and 25(OH)D level.CONCLUSION: This study suggests that vitamin D status of pregnant women and/or neonates might be improved through supplementation, adequate dairy intake, a move towards a healthy pre-pregnancy body weight, and participation in physical activity. Controlled studies are needed to determine the effectiveness of interventions aimed at these factors. V itamin D has long been known to be essential for calciumphosphorus homeostasis and bone health. The recognition that vitamin D metabolites influence other physiologic processes has prompted the examination of its effect on a range of disorders, including those in pregnancy.1 Although results among studies can be heterogeneous, evidence suggests that better vitamin D status is associated with a lower risk of gestational diabetes, pre-eclampsia, bacterial vaginosis, preterm birth, small for gestational age infants, and later child health outcomes such as low bone density, asthma and type I diabetes.

Environmental and individual predictors of 25-hydroxyvitamin D concentrations in Denmark measured from neonatal dried blood spots: the D-tect study

“…Therefore, the true effect of smoking on neonatal 25(OH)D concentration might have been underestimated. However, results from different studies suggest a non-significant inverse association between maternal smoking and maternal and neonatal 25(OH)D concentrations (21,28,59) . Therefore, maternal smoking during pregnancy might only marginally predict offspring 25(OH)D concentration at birth.…”

“…Furthermore, supplementation with vitamin D is first recommended from 2 weeks of age (53) ; therefore, 25(OH)D concentration from neonatal DBS is not expected to be affected by supplementation. Vitamin D dietary intake from supplements and dairy products has previously been identified as a determinant of vitamin D status in pregnant women and neonates (28) ; therefore, including these variables in the model would potentially have added to the explanation of a bigger proportion of the neonatal 25(OH)D variation. Furthermore, maternal body weight has been identified as a determinant of vitamin D status in pregnant women and neonates in some (28) but not all studies (20) (pregnant women only).…”

“…However, currently there is poor understanding regarding the environmental factors or individual (maternal and offspring) characteristics that best contribute to determine neonatal 25(OH)D concentrations. Previous studies describing the determinants of neonatal 25(OH)D were based on either relative small samples <300 individuals or used cord blood 25(OH)D concentration (21,(25)(26)(27)(28)(29)(30) . Only one previous study used 25(OH)D from dried blood spots (DBS) obtained from 259 children (25) .…”

A study on vitamin D levels in preterm and term neonates and their mothers

“…Similar results were also reported by Merewood et al 15 age, dairy intake and supplement use. [16][17][18] None of the mothers were taking vitamin D supplements during pregnancy. It is not a common practice to supplement antenatal mothers with vitamin D as part of the routine prenatal care in India and the vitamin D levels in the mothers are a reflection of one's own diet and lifestyle.…”

Urinary BPA and Phthalate Metabolite Concentrations and Plasma Vitamin D Levels in Pregnant Women: A Repeated Measures Analysis

“…For example, although studies investigating the relationships between phthalate and BPA exposure and physical activity are lacking, recent animal studies suggest that exposure to endocrine-disrupting chemicals such as phthalates and BPA may reduce or alter voluntary physical activity in mice ( Johnson et al 2015 ; Schmitt et al 2016 ). Because physical activity has been positively associated with 25(OH)D concentrations in pregnant women ( Moon et al 2015 ; Woolcott et al 2016 ), physical activity may be one possible mechanism through which maternal phthalate and/or BPA exposure might contribute to decreased concentrations of 25(OH)D. In the current study, we did not collect data on physical activity from our participants. Additional analyses are required to confirm the role (if any) that physical activity plays in these relationships.…”