High-Dose Vitamin D Supplementation in Pregnancy and Neurodevelopment in Childhood

Key Points Question Does maternal high-dose vitamin D supplementation in the third trimester of pregnancy improve offspring neurodevelopment in the first 6 years of life? Findings This prespecified secondary analysis of a randomized clinical trial of vitamin D3 supplementation during pregnancy and offspring neurodevelopment among 551 children showed no effect on neurodevelopment in the first 6 years of life, except for an isolated negative effect on language development at age 2 years in the high-dose compared with standard dose group. Meaning This secondary analysis of a randomized clinical trial found that maternal high-dose vitamin D3 supplementation during pregnancy did not improve neurodevelopmental outcomes in the offspring during the first 6 years of life compared with the standard recommended dose of vitamin D.


Original protocol, final protocol, summary of changes ORIGINAL PROTOCOL
The following is an English translation of the original protocol in Danish.

Aim
To investigate whether supplementation with high-dose vitamin D during third trimester of pregnancy has a favorable effect on the development of asthma and related disorders in the offspring.

Hypothesis
High-dose vitamin D3 supplementation during third trimester of pregnancy will reduce the risk of developing asthma in the offspring.

Background
Asthma, eczema and allergy are the most common chronic diseases among children and over the past 40 years, the incidence of these diseases has increased in industrialized countries through yet unknown factors in the environment. Decreased levels of maternal vitamin D in pregnancy and thereby reduced fetal vitamin D levels in utero are among the early environmental exposures suspected to have an influence on the increased incidence of asthma in children.
[1] Based on epidemiological studies, a high intake of vitamin D during pregnancy has been associated with protective effects on asthmatic symptoms in young children.[2,3] Preliminary results of a newer study indicates twice the risk of asthmatic symptoms in preschool children with low vitamin D levels at birth compared to children with a high level of vitamin D levels at birth. [4] The results are consistent with several other studies, which suggest that the population in westernized countries have a reduced supply and level of vitamin D leading to an increased risk of various diseases. E.g., vitamin D levels in the fetus has been associated with the development of schizophrenia, diabetes mellitus and bone development.[5-7] Furthermore, high levels of vitamin D in adults appears to protect against a number of diseases, including bone diseases and cancer. [8][9][10] The reason for these reduced levels of vitamin D may be found in the lifestyle of modern society. The majority of our vitamin D supply derives from sun exposure, and because of increasing awareness of harmful effects of sun exposure in relation to skin cancer, our supply of vitamin D has been markedly reduced. This is a recent development, which has led to the hypothesis that the current levels of vitamin D is too low according to the level for which we are genetically programmed. Vitamin D level is however associated with and highly influenced by other factors as well. Therefore, it is necessary to conduct controlled, blinded studies on the effect of vitamin D supplementation to provide sufficient basis for future recommendations.
The study is a double-blinded, placebo-controlled, randomized parallel group design. 800 pregnant women will be randomized in a 1:1 ratio to intake of either high dose vitamin D supplementation or placebo according to one of the following regimes: 1) Placebo (+ guidance in recommended supplement of vitamin D (400 units daily)) or 2) High dose vitamin D supplement (2400units daily) (+ guidance in recommended supplement of vitamin D (400units daily)) The regimes are administered orally as 2 tablets daily.
Blinding and randomization are carried out by the Capital Region Pharmacy and stratified according to treatment group in the fish oil intervention study (ClinicalTrials.gov: NCT00798226). This allows for equal numbers receiving high dose vitamin D supplementation in both the fish oil active group and the fish oil placebo group.
The intervention is initiated at the beginning of the third trimester (pregnancy week 24) and continued until 1 st visit to the COPSAC clinic after birth at week 1-2 postpartum. At the clinical visit in pregnancy week 24, the women will be provided with the intervention treatment and interviewed about current daily vitamin D intake and history of diseases likely to influence vitamin D levels. At pregnancy week 36 adherence to the regime will be assessed by interview at the COPSAC clinic. Furthermore, the women will be instructed to return the remaining tablets at the end of the intervention for evaluation of their compliance.
At pregnancy week 24 and 1 st visit after birth a blood sample will be drawn from the mother in order to measure 25-OH-vitamin D, total calcium, parathyroid-hormone (PTH) and alkaline phosphatase.

Inclusion criteria
The study population consists of healthy pregnant women and their children participating in the COPSAC2010 cohort. Vitamin D supplements are administered during the third pregnancy trimester. The women will be included in the study independent of residence, age, race and social status during week 22-26 of pregnancy.

Exclusion criteria
Pregnant women are excluded from the trial, if they carry a d isease leading to an increased risk of potential side effects from high-dose vitamin D supplementation: Endocrinologic disease in the form of calcium metabolic disorders, parathyoroidea disease, thyroid disorders or type 1 diabetes; Tuberculosis; Sarcoidosis or illness requiring chronic treatment with diuretics or heart medications, including calcium channel blockers or if they have a current intake of vitamin D supplements over the recommended dose.

Risks and disadvantages:
Known potential adverse effects of vitamin D intoxication is hypercalcemia and accompanying symptoms such as loss of appetite, nausea, vomiting, weight loss, headache, lethargy, fatigue, confusion and renal impairment. These side effects are not found by the administration of vitamin D in physiological doses. Vitamin D intoxication occurs only by the intake of very high doses of Vitamin D (4 times higher doses than administered in our study). In order to avoid administering vitamin D supplements to women with a high initial level, women with an intake above the recommended dose in the previous 6 months are excluded. Expected disadvantages related to blood sample procedures and are temporary in nature without the risk of permanent injury.

Ethical aspects
Oral vitamin D supplement has been shown to be safe and non-toxic in many randomized trials, including studies involving pregnant women. The risk of adverse effects in the pregnant woman or the fetus is suspected to be minimal. Based on the previous studies, it is expected that a large proportion of the participating women will have a daily low Vitamin D level, and therby vitamin D supplementation to these women will be a health benefit. The control group receive recommended dose of vitamin D, and ethical problems in relation to sufficient treatment of the control group is thereby not a problem.
We believe that the study as outlined above is ethically acceptable and randomized trials of vitamin D supplements are necessary for future recommendations of vitamin D intake. The aim of this study is to prevent asthma symptoms (recurrent wheeze) in childhood by supplementation with high dose vitamin D to the mother during pregnancy. Participants are mothers and children of the ABC (Asthma Begins in Childhood) cohort. Mothers are recruited during pregnancy and receive daily supplement with 2400 IU of Vitamin D3 or placebo from week 24 of gestation to 1 week after delivery. In addition all mothers are advised to take the recommended dose of 400 IU vitamin D daily. The mothers in ABC also participate in an interventional trial with fish oil supplementation, and the vitamin D randomization is stratified by fish oil treatment group. The child is followed with acute and planned vits at the research unit, and wheeze is diagnosed according to predefined algorithms. 12. 17q21 genotype and sphingolipid metabolites In a secondary analyses, we will determine the effect of 17q21 genotype on the efficacy of vitamin D supplementation in the prevention of asthma/wheeze. We will compute hazard ratios for the reduction in asthma/wheeze risk associated with prenatal supplementation, stratified by rs12936231. rs12936231 is a functional SNP influencing expression of ORMDL3, and given the role of ORMDL3 as a key sphingolipid biosynthesis regulator, we will subsequently investigate the relative abundance of sphingolipids between those in the vitamin D Intervention arm and those in the placebo group, stratified by 17q21 genotype. Finally we will identify interactions between prenatal vitamin D supplementation, rs12936231 genotype and sphingolipid metabolism in the risk of asthma/wheeze by age three.

Arms and interventions:
[ Other Pre-specified Outcome Measures: 14. Asthma Asthma diagnosed from age 3 to 10 years based on the same predefined algorithm of recurrent troublesome lung symptoms, response to treatment after withdrawal of treatment, which was used for persistent wheeze at age 0-3 in phase 1 of the study. Primary outcome in phase 2 is current asthma at specific visits till age 10 years, which is diagnosed in children fulfilling the persistent wheeze algorithm at any point during the first 10 years of life and still needing inhaled corticosteroids at specific visits (3, 4, 5, 6, 8 and 10 years of age) to control the symptoms. 20. MRI scanning of the Brain Following technics will be used. Structural MRI scanning to distinguish between grey and white matter. Diffusion weighted imaging to register the fiber directions in the brain. Magnetisation transfer imaging to measure the magnetisation transfer ratio reflecting the interaction between macromolecular protons and the free water protons of tissue, and this technique in addition to quantitative T1-mapping will be used to assess myelination in the developing brain. Magnetic resonance spectroscopy (MRS) allows for non-invasive measurement of metabolites. Phase-contrast MR angiography to detect the total cerebral blood flow. zsArterial spin labelling to measure cerebral blood perfusion. [