Estimation of the maternal vitamin D intake that maintains circulating 25-hydroxyvitamin D in late gestation at a concentration sufficient to keep umbilical cord sera ≥25-30 nmol/L: a dose-response, double-blind, randomized placebo-controlled trial in pregnant women at northern latitude

Loss of maternal calcitriol reversibly alters early offspring growth and skeletal development in mice

Ablation of Cyp27b1 eliminates calcitriol but does not disturb fetal mineral homeostasis or skeletal development. However, independent of fetal genotypes, maternal loss of Cyp27b1 altered fetal mineral and hormonal levels compared to offspring of WT dams. We hypothesized that these maternal influences would alter postnatal skeletal development. Cyp27b1 null and WT females were mated to bear only Cyp27b1+/- offspring. Forty-eight hours after birth, pups were cross-fostered to dams of the same or opposite genotype that bore them. Maternal and offspring samples were collected on days 21 (weaning) and 42. Offspring measurements included minerals and hormones, BMC by DXA, ash weight and mineral content, gene expression, 3-point bending tests, and microCT. Maternal lactational behavior was evaluated. Milk was analyzed for nutritional content. At day 21, offspring fostered by nulls, independent of birth dam, had ~20% lower weight, BMC, ash weight, and ash calcium than pups fostered by WT dams. Adjustment for body weight accounted for the lower BMC but not the lower ash weight and ash calcium. Hormones and serum/urine minerals did not differ across offspring groups. Offspring fostered by nulls had shorter femurs and lower cortical thickness, mean polar moment of inertia, cortical area, trabecular bone volume, and trabecular number. Dam lactational behaviors and milk nutritional content did not differ between groups. At day 42, body weight, ash weight, lengths, BMC, and tibial bone strength were no longer different between pups fostered by null vs WT dams. In summary, pups fostered by Cyp27b1 nulls, regardless of birth dam, have proportionately smaller skeletons at 21 d, impaired microstructure, but normal mineral homeostasis. The skeletal effects are largely recovered by day 42 (3 wk after weaning). In conclusion, maternal loss of calcitriol impairs early postnatal cortical bone growth and trabecular bone mass, but affected offspring catch up after weaning.

Vitamin D Supplementation: A Review of the Evidence Arguing for a Daily Dose of 2000 International Units (50 µg) of Vitamin D for Adults in the General Population

Vitamin D deficiency is considered a public health problem due to its worldwide high prevalence and adverse clinical consequences regarding musculoskeletal health. In addition, vitamin D may also be crucial for the prevention of certain extraskeletal diseases. Despite decades of intensive scientific research, several knowledge gaps remain regarding the precise definition of vitamin D deficiency and sufficiency, the health benefits of improving vitamin D status, and the required vitamin D intakes. Consequently, various societies and expert groups have released heterogeneous recommendations on the dosages for vitamin D supplementation. In this brief narrative review, we outline and discuss recent advances regarding the scientific evidence arguing for a daily vitamin D supplementation with 2000 international units (IU) (50 µg) of vitamin D3 to prevent and treat vitamin D deficiency. According to data from randomized controlled trials (RCTs), such a dose may improve some health outcomes and is sufficient to raise and maintain serum 25(OH)D concentrations above 50 nmol/L (20 ng/mL) and above 75 nmol/L (30 ng/mL) in >99% and >90% of the general adult population, respectively. According to large vitamin D RCTs, there are no significant safety concerns in supplementing such a dose for several years, even in individuals with an already sufficient vitamin D status at baseline. A daily vitamin D supplementation with 2000 IU (50 µg) may be considered a simple, effective, and safe dosage to prevent and treat vitamin D deficiency in the adult general population.

Quantification and reporting of vitamin D concentrations measured in human milk by LC-MS/MS

Vitamin D is essential for optimal bone health, and vitamin D deficiency has been associated with an increased risk of adverse pregnancy, growth and developmental outcomes. In early life, and in the absence of endogenous vitamin D production from UVB light, infants are reliant on vitamin D stores established in utero and the vitamin D supply from human milk (HM). However, comprehensive data on vitamin D in HM is lacking. Thus, in this review we explore the application of liquid-chromatography tandem mass spectrometry (LC-MS/MS) to the assessment of vitamin D in HM. We discuss the challenges of extracting and measuring multiple vitamin D metabolites from HM including the frequent requirement for a large sample volume, and inappropriate poor sensitivity. Shortcomings in the reporting of experimental procedures and data analysis further hinder advances in the field. Data collated from all studies that have applied LC-MS/MS reveal that, in general, cholecalciferol concentration is greater and more variable than 25-hydroxyvitamin D concentration, and that the vitamin D content of HM is low and less than the currently recommended dietary requirement of infants, although maternal supplementation can increase the vitamin D content of HM. Improvements in analytical methods and their validation and larger, more representative studies are required to better characterize HM milk vitamin D metabolite concentrations and their relationship with maternal status. These data are essential to understand relationships with infant health and to inform public health policies around vitamin D fortification and supplementation.

Associations between Vitamin D Deficiency and Carbohydrate Intake and Dietary Factors in Taiwanese Pregnant Women

This cross-sectional observation study investigated the vitamin D (VD) status in Taiwanese pregnant women and the effects of VD supplementation and macronutrient intake on serum 25-hydroxy-vitamin D (25[OH]D) level. Data on VD intake, daily sunlight exposure, and carbohydrate intake were obtained from 125 pregnant women at 30−37 weeks’ gestation. Serum 25[OH]D level was measured before delivery in all enrolled women; and the mean 25(OH)D level was 43 nmol/L or 17.2 ng/mL. The 25(OH)D level was significantly correlated with total VD intake of pregnant women (r = 0.239; p = 0.007). The severe VD deficiency group (n = 16; mean of 25(OH)D level = 8.5 ng/mL) had significantly lower total VD intake and supplementation than the groups with VD deficiency (n = 69), insufficiency (n = 32), and sufficiency (n = 8). Those with ≥400 IU/day total VD intake (including VD from food and supplementation) had significantly higher 25(OH)D concentration than those with <400 IU/day total VD intake. Those with 400 IU/day VD supplementation could significantly increase serum 25(OH)D concentrations for pregnant women. Among 85 pregnant women with carbohydrate intake of ≥300 g/day, serum 25(OH)D levels were negatively correlated with carbohydrate intake (p = 0.031). In conclusion, VD deficiency was highly prevalent in Taiwanese pregnant women. VD supplementation was the most effective method for increasing 25(OH)D concentration in pregnant women. Higher carbohydrate intake might reduce 25(OH)D levels.

Vitamin and mineral levels during pregnancy

OBJECTIVE

Numerous physiological changes occur during pregnancy, which affect both the mother and the fetus. The objective of this study was to evaluate the magnesium, calcium, phosphate, parathormone (PTH), and vitamin D levels in each trimester of pregnancy.

METHODS

In this study, 30 pregnant women in the first trimester, 30 pregnant women in the second trimester, 30 pregnant women in the third trimester, and 30 healthy, non-pregnant women (control) in the same age group were included. The serum magnesium, calcium, phosphate, PTH, and vitamin D levels were measured in all the participants.

RESULTS

No statistically significant difference was found in the PTH and phosphate levels within the groups. In contrast, a significant difference was found in the vitamin D, calcium, and magnesium levels (p<0.001 for all). By analyzing the differences between the groups, the vitamin D, calcium, and magnesium levels were found to decrease with increase in the gestational weeks.

CONCLUSION

For maintaining a healthy pregnancy and fetus, we recommend vitamin D, calcium, and magnesium levels to be included in routine follow-ups for each trimester and supplemented in case of deficiency.

Vitamin D Status of Infants of Mothers with Gestational Diabetes: Status at Birth and a Randomized Controlled Trial of Vitamin D Supplementation across Infancy

BACKGROUND

Vitamin D status and requirements of infants of women with gestational diabetes mellitus (GDM) are unclear.

OBJECTIVES

The objectives were to assess vitamin D status in infants of mothers with GDM and compare vitamin D status in response to 400 vs. 1000 IU/d vitamin D supplementation in infants born with serum 25-hydroxyvitamin D [25(OH)D] <50 nmol/L.

METHODS

Women with GDM delivering full-term infants (n = 98; March 2017-2019, Montreal, Canada) were surveyed for demographic and lifestyle factors. Pregnancy history was obtained from medical records. Newborn serum 25(OH)D was measured (immunoassay) and categorized as <30 (deficient) or ≥40 nmol/L (adequate). Breastfed neonates (n = 16) with serum 25(OH)D <50 nmol/L at birth were randomly assigned to 400 or 1000 IU/d of supplemental cholecalciferol (vitamin D3), and serum 25(OH)D was measured at baseline (≤1 mo) and 3, 6, and 12 mo of age. Groups were compared using a linear mixed-effects model and Tukey-Kramer post hoc tests.

RESULTS

Mean newborn serum 25(OH)D was 46.4 (95% CI: 43.9, 49.9) nmol/L, with 15.3% (95% CI: 8.2%, 22.4%) <30 nmol/L and 61.2% (95% CI: 51.6%, 70.9%) ≥40 nmol/L. During the trial, most infants were breastfed to 3 mo (400 IU/d: 87.5%; 1000 IU/d: 75.0%). Mean (± SEM) infant serum 25(OH)D was higher in the 1000-IU/d group at 3 mo (79.9 ± 5.9 vs. 111.5 ± 15.2 nmol/L; P = 0.0263), and although not different at 6-12 mo, was maintained at >50 nmol/L.

CONCLUSIONS

Most infants of women with GDM had adequate vitamin D status in this study. In those born with serum 25(OH)D <50 nmol/L, vitamin D status was corrected by 3 mo of age in response to 400 or 1000 IU/d of supplemental vitamin D. Dietary guidance should continue to recommend that all women who could become pregnant take a multivitamin supplement and that breastfed infants receive 400 IU/d of supplemental vitamin D. This study and ancillary trial were registered at clinicaltrials.gov (https://www.

CLINICALTRIALS

gov/ct2/show/NCT02563015) as NCT02563015.

Dietary supplementation of 25-hydroxycholecalciferol as an alternative to cholecalciferol in swine diets: A review

25-hydroxycholecalciferol (25-OHD₃ ) formed via hepatic hydroxylation from vitamin D, cholecalciferol, represents the precursor of the biologically active vitamin D hormone, 1,25-dihydroxyvitamin D. Due to a higher absorption rate and the omission of one hydroxylation, dietary supplementation of 25-OHD₃ instead of vitamin D₃ is considered to be more efficient as plasma concentrations of 25-OHD₃ are increased more pronounced. The present review summarises studies investigating potential beneficial effects on mineral homeostasis, bone metabolism, health status and performance in sows, piglets and fattening pigs. Results are inconsistent. While most studies could not demonstrate any or only a slight impact of partial or total replacement of vitamin D₃ by 25-OHD₃ , some experiments indicated that 25-OHD₃ might alter physiological processes when animals are challenged, for example, by a restricted mineral supply.

An Update on the Effects of Vitamin D on the Immune System and Autoimmune Diseases

Vitamin D intervenes in calcium and phosphate metabolism and bone homeostasis. Experimental studies have shown that 1,25-dihydroxyvitamin D (calcitriol) generates immunologic activities on the innate and adaptive immune system and endothelial membrane stability. Low levels of serum 25-hydroxyvitamin D (25(OH)D) are associated with an increased risk of developing immune-related diseases such as psoriasis, type 1 diabetes, multiple sclerosis, and autoimmune diseases. Various clinical trials describe the efficacy of supplementation of vitamin D and its metabolites for treating these diseases that result in variable outcomes. Different disease outcomes are observed in treatment with vitamin D as high inter-individual difference is present with complex gene expression in human peripheral blood mononuclear cells. However, it is still not fully known what level of serum 25(OH)D is needed. The current recommendation is to increase vitamin D intake and have enough sunlight exposure to have serum 25(OH)D at a level of 30 ng/mL (75 nmol/L) and better at 40–60 ng/mL (100–150 nmol/L) to obtain the optimal health benefits of vitamin D.

Vitamin D deficiency in South-East Asian children: a systematic review

OBJECTIVE

To describe the prevalence and determinants of vitamin D deficiency (VDD) among healthy children aged between 0 and 18 years living in South-East Asia (SEA).

DESIGN

We systematically searched Ovid MEDLINE and Ovid EMBASE for observational studies assessing VDD among healthy children in the SEA region as the primary or secondary outcome from database inception to 6 April 2021. PubMed was used for e-pubs and publications not indexed in Medline. Publications that included abstracts in English were included. We performed a systematic review to describe the prevalence of VDD in SEA children.

RESULTS

Our initial search identified 550 publications with an additional 2 publications from manual screening. Of those, 21 studies from 5 different countries (Thailand, Indonesia, Vietnam, Malaysia and Cambodia) were summarised and included in forest plots. The prevalence of VDD (<50 nmol/L) ranged from 0.9% to 96.4%, with >50% of newborns having VDD, and severe VDD (<30 nmol/L) ranged from 0% to 55.8%. Female sex and urban living were the most common determinants of VDD.

CONCLUSIONS

VDD among healthy children living in the SEA region is common. Efforts to detect VDD and the implementation of preventive measures, including education on safe sun exposure and oral vitamin D supplementation or food fortification, should be considered for key target groups, including adolescent females and pregnant and lactating women to improve the vitamin D status of newborns.

PROTOCOL REGISTRATION NUMBER

This study is registered with PROSPERO (CRD42020181600).

Vitamin D supplementation during pregnancy to prevent vitamin D deficiency in newborns: a systematic review and meta-analysis

Abstract Objectives: to assess the effects of vitamin D supplementation during pregnancy on the outcomes of vitamin D concentration in newborns, length at birth, overall health (Apgar), birth weight and maternal vitamin D concentration after childbirth. Methods: this research was conducted in the electronic databases of MEDLINE, LILACS, EMBASE and Cochrane Library until December 2020, using the terms “vitamin D”, “pregnancy”, “vitamin D deficiency”, “infant”, “newborn” and their synonyms. Randomized controlled trials were searched by evaluating the effects of maternal vitamin D supplementation in neonates. The data was analyzed on RevMan 5.4 software and the quality of evidence on GRADE. Results: the newborn’s overall health condition was presented as Apgar, with a mean difference (MD) of 0.15 (CI95%=0.06-0.25; p=0.002; I2=0%, two studies, 648 participants, moderate quality evidence) at the first minute and 0.11 (CI95%=0.04-0.17; p=0.001; I2=0%, two studies, 648 participants, moderate quality evidence) at the fifth minute. Significant effects were also presented at the length at birth considering any supplemented dose (MD=0.19; CI95%=0.08-0.30; p=0.0010; I2=0%, 1452 participants, low quality evidence) and birth weight in doses higher than 4000IU/day (MD=257.05 (CI95%=137.81-376.29; p<0.0001; I2=14%, 176 participants, moderate quality evidence). Conclusion: vitamin D supplementation during pregnancy improves serum 25 (OH) D concentration and suggests positive effects on overall health condition, length at birth and birth weight. PROSPERO CRD42017073292.

Implementation strategies for improving vitamin D status and increasing vitamin D intake in the UK: current controversies and future perspectives: proceedings of the 2nd Rank Prize Funds Forum on vitamin D

A multi-disciplinary expert group met to discuss vitamin D deficiency in the UK and strategies for improving population intakes and status. Changes to UK Government advice since the 1st Rank Forum on Vitamin D (2009) were discussed, including rationale for setting a reference nutrient intake (10 µg/d; 400 IU/d) for adults and children (4+ years). Current UK data show inadequate intakes among all age groups and high prevalence of low vitamin D status among specific groups (e.g. pregnant women and adolescent males/females). Evidence of widespread deficiency within some minority ethnic groups, resulting in nutritional rickets (particularly among Black and South Asian infants), raised particular concern. Latest data indicate that UK population vitamin D intakes and status reamain relatively unchanged since Government recommendations changed in 2016. Vitamin D food fortification was discussed as a potential strategy to increase population intakes. Data from dose-response and dietary modelling studies indicate dairy products, bread, hens' eggs and some meats as potential fortification vehicles. Vitamin D3 appears more effective than vitamin D2 for raising serum 25-hydroxyvitamin D concentration, which has implications for choice of fortificant. Other considerations for successful fortification strategies include: (i) need for 'real-world' cost information for use in modelling work; (ii) supportive food legislation; (iii) improved consumer and health professional understanding of vitamin D's importance; (iv) clinical consequences of inadequate vitamin D status and (v) consistent communication of Government advice across health/social care professions, and via the food industry. These areas urgently require further research to enable universal improvement in vitamin D intakes and status in the UK population.

Vitamin D biomarkers for Dietary Reference Intake development in children: a systematic review and meta-analysis

BACKGROUND

Circulating 25-hydroxyvitamin D [25(OH)D] has been the accepted vitamin D exposure/intake biomarker of choice within recent DRI exercises, but use of other vitamin D-related biomarkers as well as functional markers has been suggested. These may be of value in future vitamin D DRI exercises, such as the FAO/WHO's one for young children.

OBJECTIVES

To systematically review the usefulness of circulating 25(OH)D, parathyroid hormone (PTH), free and bioavailable 25(OH)D, C3-epimer of 25(OH)D, vitamin D3, 24,25-dihydroxyvitamin D [24,25(OH)2D], and bone turnover markers and calcium absorption as vitamin D biomarkers for DRI development in children.

METHODS

Methods included structured searches of published articles, full-text reviews, data extraction, quality assessment, meta-analysis, and random-effects meta-regression.

RESULTS

Fifty-nine vitamin D supplementation randomized controlled trials (RCTs) were included (39 in infants/children as the priority group and the remainder in adults since pediatric studies were absent/limited). Vitamin D supplementation significantly raised circulating 25(OH)D in infants and children, but the response was highly heterogeneous [weighted mean difference (WMD): 27.7 nmol/L; 95% CI: 22.9, 32.5; 27 RCTs; I2 = 93%]. Meta-regression suggested an increase by 1.7 nmol/L (95% CI: 0.7, 2.6) in serum 25(OH)D per each 100-IU increment in vitamin D intake (P = 0.0005). Vitamin D supplementation had a significant effect on circulating 24,25(OH)2D (WMD: 3.4 nmol/L; 95% CI: 2.4, 4.5; 13 RCTs; I2 = 95%), with a dose-response relation (+0.15 nmol/L per 100 IU; 95% CI: -0.01, 0.29). With circulating PTH, although there was a significant effect of vitamin D on WMD (P = 0.05), there was no significant dose-response relation (P = 0.32). Pediatric data were too limited in relation to the usefulness of the other biomarkers.

CONCLUSIONS

Circulating 25(OH)D may be a useful biomarker of vitamin D exposure/intake for DRI development in infants and children. Circulating 24,25(OH)2D also showed some promise, but further data are needed, especially in infants and children.

Critical Appraisal of Large Vitamin D Randomized Controlled Trials

As a consequence of epidemiological studies showing significant associations of vitamin D deficiency with a variety of adverse extra-skeletal clinical outcomes including cardiovascular diseases, cancer, and mortality, large vitamin D randomized controlled trials (RCTs) have been designed and conducted over the last few years. The vast majority of these trials did not restrict their study populations to individuals with vitamin D deficiency, and some even allowed moderate vitamin D supplementation in the placebo groups. In these RCTs, there were no significant effects on the primary outcomes, including cancer, cardiovascular events, and mortality, but explorative outcome analyses and meta-analyses revealed indications for potential benefits such as reductions in cancer mortality or acute respiratory infections. Importantly, data from RCTs with relatively high doses of vitamin D supplementation did, by the vast majority, not show significant safety issues, except for trials in critically or severely ill patients or in those using very high intermittent vitamin D doses. The recent large vitamin D RCTs did not challenge the beneficial effects of vitamin D regarding rickets and osteomalacia, that therefore continue to provide the scientific basis for nutritional vitamin D guidelines and recommendations. There remains a great need to evaluate the effects of vitamin D treatment in populations with vitamin D deficiency or certain characteristics suggesting a high sensitivity to treatment. Outcomes and limitations of recently published large vitamin D RCTs must inform the design of future vitamin D or nutrition trials that should use more personalized approaches.

Maternal and Neonatal 3-epi-25-hydroxyvitamin D Concentration and Factors Influencing Their Concentrations

BACKGROUND

Little is known about the presence of 3-epi-25 hydroxyvitamin D in maternal and neonatal circulation, the extent of its contribution to total 25 hydroxyvitamin D, or factors influencing its levels.

METHODS

A total of 1502 and 1321 archived maternal and umbilical cord serum samples from the Hyperglycemia and Adverse Pregnancy Outcome Study cohort from Hong Kong were assayed for 25(OH)D2, 25(OH)D3, and isomeric form of 25(OH)D3 (3-epi-25(OH)D3) by a liquid chromatography-tandem mass spectrometry method.

RESULTS

Vitamin D deficiency (total serum 25(OH)D level < 50 nmol/L) and severe vitamin D deficiency (total serum 25(OH)D level < 25 nmol/L) occurred in 590 (39.3%) and 25 (1.7%) mothers, respectively. 3-epi-25(OH)D3 could be detected in 94.5% of maternal and 92.1% of neonatal umbilical sera, with the highest 3-epi-25(OH)D3 levels contributing to 19.9% and 15.3% of the maternal and umbilical cord sera 25(OH)D3 levels, respectively. Pregnancy with a male fetus, ambient solar radiation, and maternal glycemia and 25(OH)D3 levels were independent factors associated with maternal 3-epi-25(OH)D3 level. Advanced maternal age, multiparity, maternal gestational weight gain below the Institute of Medicine recommendation, maternal glycemic status, and earlier gestational age at delivery were significantly associated with higher umbilical cord serum 3-epi-25(OH)D3.

CONCLUSIONS

3-epi-25(OH)D3 accounted for a significant portion of total 25(OH)D in maternal and neonatal circulations. Further study is needed to determine the possible mechanism underlying this observation.

Safety of Vitamin D Food Fortification and Supplementation: Evidence from Randomized Controlled Trials and Observational Studies

The safety considerations of food-based solutions for vitamin D deficiency prevention, such as fortification and supplementation, are critical. On the basis of collective data from 20 randomized controlled trials (RCTs) and 20 national healthy surveys, as well as prospective cohort studies (PCSs) across the ODIN project (“Food-based solutions for optimal vitamin D nutrition and health through the life cycle”, FP7-613977), we analyzed the potential safety issues arising from vitamin D intakes and/or supplementation. These adverse consequences included high serum 25-hydroxyvitamin D (S-25(OH)D) concentrations (>125 nmol/L), high serum calcium concentrations, and vitamin D intakes in excess of the tolerable upper intake levels (ULs). In the RCTs (n = 3353, with vitamin D doses from 5–175 µg/day), there were no reported adverse effects. The prevalence of high S-25(OH)D was <10% when vitamin D supplements were administered, and <0.1% for fortified foods. Elevated serum calcium was observed among <0.5% in both administration types. No ODIN RCT participants exceeded the age-specific ULs. In observational studies (n = 61,082), the prevalence of high 25(OH)D among children/adolescents, adults, and older adults was <0.3%, with no evidence of adverse effects. In conclusion, high S-25(OH)D concentrations >125 nmol/L were rare in the RCTs and PCSs, and no associated adverse effects were observed.

Could Vitamin D Be Effective in Prevention of Preeclampsia?

Prevention of preeclampsia (PE) remains one of the most significant problems in perinatal medicine. Due to the possible unpredictable course of hypertension in pregnancy, primarily PE and the high complication rate for the mother and fetus/newborn, it is urgent to offer pregnant women in high-risk groups effective methods of preventing the PE development or delaying its appearance. In addition, due to the association of PE with an increased risk of developing cardiovascular diseases (CVD) in later life, effective preeclampsia prevention could also be important in reducing their incidence. Ideal PE prophylaxis should target the pathogenetic changes leading to the development of PE and be safe for the mother and fetus, inexpensive and freely available. Currently, the only recognized method of PE prevention recommended by many institutions around the world is the use of a small dose of acetylsalicylic acid in pregnant women with risk factors. Unfortunately, some cases of PE are diagnosed in women without recognized risk factors and in those in whom prophylaxis with acetylsalicylic acid is not adequate. Hence, new drugs which would target pathogenetic elements in the development of preeclampsia are studied. Vitamin D (Vit D) seems to be a promising agent due to its beneficial effect on placental implantation, the immune system, and angiogenic factors. Studies published so far emphasize the relationship of its deficiency with the development of PE, but the data on the benefits of its supplementation to reduce the risk of PE are inconclusive. In the light of current research, the key issue is determining the protective concentration of Vit D in a pregnant woman. The study aims to present the possibility of using Vit D to prevent PE, emphasizing its impact on the pathogenetic elements of preeclampsia development.

Disparities in Vitamin D Status of Newborn Infants from a Diverse Sociodemographic Population in Montreal, Canada

BACKGROUND

Vitamin D status at birth is reliant on maternal-fetal transfer of vitamin D during gestation.

OBJECTIVES

We aimed to examine the vitamin D status of newborn infants in a diverse population and to subsequently identify the modifiable correlates of vitamin D status.

METHODS

In this cross-sectional study, healthy mother-infant dyads (n = 1035) were recruited within 36 h after term delivery (March 2016-March 2019). Demographic and lifestyle factors were surveyed. Newborn serum 25-hydroxyvitamin D [25(OH)D] was measured (standardized chemiluminescence immunoassay) and categorized as deficient [serum 25(OH)D <30 nmol/L] or adequate (≥40 nmol/L). Serum 25(OH)D was compared among categories of maternal characteristics using ANOVA; each characteristic was tested in a separate model. Subgroups (use of multivitamins preconception and continued in pregnancy compared with during pregnancy only) were matched (n = 352/group) for maternal factors (ancestry, age, income, education, parity, and prepregnancy BMI) using propensity scores; logistic regression models were generated for odds of deficiency or adequacy.

RESULTS

Infants' mean serum 25(OH)D was 45.9 nmol/L (95% CI: 44.7, 47.0 nmol/L) (n = 1035), with 20.8% (95% CI: 18.3%, 23.2%) deficient and 60.7% (95% CI: 55.2%, 66.2%) adequate. Deficiency prevalence ranged from 14.6% of white infants to 41.7% of black infants. Serum 25(OH)D was higher (P < 0.0001) in infants of mothers with higher income, BMI < 25 kg/m2, exercise and sun exposure in pregnancy, and use of multivitamins preconception. In the matched-subgroup analysis, multivitamin supplementation preconception plus during pregnancy relative to only during pregnancy was associated with lower odds for vitamin D deficiency (ORadj: 0.55; 95% CI: 0.36, 0.86) and higher odds for adequate vitamin D status (ORadj: 1.47; 95% CI: 1.04, 2.07).

CONCLUSIONS

In this study most newborn infants had adequate vitamin D status, yet one-fifth were vitamin D deficient with disparities between population groups. Guidelines for a healthy pregnancy recommend maternal use of multivitamins preconception and continuing in pregnancy. An emphasis on preconception use may help to achieve adequate neonatal vitamin D status.This trial was registered at clinicaltrials.gov as NCT02563015.

Longitudinal changes in vitamin D and its metabolites in pregnant South Africans

BACKGROUND

Vitamin D deficiency (VDD) has been associated with adverse maternal and foetal outcomes and is determined by measuring 25 hydroxyvitamin D (25(OH)D). The 25(OH)D is catabolized to 24, 25-(OH) ₂D and the ratio of 25(OH) D to 24, 25-(OH)₂D, the vitamin D metabolite ratio (VMR), is thought to be a superior marker of VDD, being elevated in such states. The aims of this study were to assess the longitudinal vitamin D status of pregnant women by measuring cholecalciferol, 25(OH)D, 24, 25-(OH)₂D and VMR at two time points and also to determine any association of vitamin D and metabolites with gestational age at birth, birth length and weight.

METHODS

We recruited 400 pregnant black African women in their first trimester (V1) and measured weights and heights. Ultrasound scans were performed for gestational age. Blood was drawn at V1 and at about 26 weeks (V2) of gestation for cholecalciferol, 25(OH)D, 24, 25-(OH)₂D, VMR and parathyroid hormone (PTH). An OGTT was performed at V2 where fasting glucose, insulin and 30-minute glucose were measured. At birth, we measured birth weight, length and gestational age. Maternal insulin, PTH and vitamin D binding protein (VDBP) were measured by immunoassay. Maternal albumin was measured colorimetrically. Maternal cholecalciferol, 25(OH)D and 24, 25-(OH)₂D, were measured by mass spectrometry and free and bioavailable vitamin D were calculated. Initial gestation was determined by ultrasound. We compared analytes by visit as well as by 25(OH)D status. Vitamin D deficiency (<30 nmol/L) was defined according to the National Academy of Medicine guidelines. Linear regression analysis was used to determine associations of vitamin D molecules with maternal blood pressure, fasting and 30-minute insulin and blood glucose and neonatal parameters.

RESULTS

Results are presented for participants for whom we had complete data (n = 330-346 depending on variable). The prevalence of vitamin D deficiency (VDD) was 35.8 % at V1 and 32.4 % at V2. Levels of 25(OH)D did not change significantly between visits. Levels of 24, 25(OH)₂D dropped from the first to the second visit (17.64 ± 12.64 to 9.39 ± 9.07 nmol/L; p < 0.0001) while VMR increased ((3.15 (1.31; 7.67) to 7.90 (2.44; 25.98); p < 0.0001). The proportion of women with the lowest cholecalciferol concentrations increased at V2 compared to the V1 (36.1-42.8 %; p = 0.02). In multivariable regression models 25(OH)D was negatively associated with 30-minute glucose concentrations (p = 0.038) whilst 24, 25-(OH)₂D was positively associated with fasting insulin (p = 0.017) and HOM A-I R (p = 0.023). There was no correlation of 25(OH)D or metabolites with infant birth weight, birth length or gestational age.

CONCLUSIONS

Maternal VDD is common in pregnant black South African women. Decreased VMR suggest that catabolism of 25(OH)D is reduced in pregnancy to maintain adequate free vitamin D levels.

Inadequate vitamin D intake among pregnant women in Malaysia based on revised recommended nutrient intakes value and potential dietary strategies to tackle the inadequacy

BACKGROUND/OBJECTIVES

Recently, the recommended nutrient intakes (RNI) for vitamin D for Malaysian aged 1-70 yrs has been revised from 5 µg/day to 15 µg/day. This study is aimed to assess the adequacy of vitamin D intake based on revised RNI and to recommend several dietary strategies to increase total vitamin D intake.

SUBJECTS/METHODS

Vitamin D intake from both food and supplement of 217 pregnant women was assessed using a validated food frequency questionnaire. Hypothetical effect of expanded supplementation and food fortifications strategies were modelled using the consumption data.

RESULTS

The results revealed that more than half (67.7%) of pregnant women had inadequate vitamin D intake (RNI < 15 µg/day). The modelling results demonstrated the potential of universal provision of 10 µg/day of multivitamins supplements in increasing vitamin D intake. Moreover, mandatory fortification of both milk and malted drink at single level of 5 µg/serving would lead to increase in vitamin D intake of Malaysians, particularly pregnant women.

CONCLUSIONS

The outcome of this study can be used as a reference for public health professionals to re-evaluate the existing Malaysian food fortification policies and supplementation recommendation for vitamin D for pregnant women.

Basal Vitamin D Status and Supplement Dose Are Primary Contributors to Maternal 25-Hydroxyvitamin D Response to Prenatal and Postpartum Cholecalciferol Supplementation

BACKGROUND

Variability in the 25-hydroxyvitamin D [25(OH)D] response to prenatal and postpartum vitamin D supplementation is an important consideration for establishing vitamin D deficiency prevention regimens.

OBJECTIVES

We aimed to examine interindividual variation in maternal and infant 25(OH)D following maternal vitamin D supplementation.

METHODS

In a randomized trial of maternal vitamin D supplementation (Maternal Vitamin D for Infant Growth Trial), healthy pregnant women (n = 1300) received a prenatal cholecalciferol (vitamin D-3) dose of 0, 4200, 16,800, or 28,000 IU/wk from 17 to 24 wk of gestation followed by placebo to 6 mo postpartum. A fifth group received 28,000 IU cholecalciferol/wk both prenatally and postpartum. In a subset of participants, associations of 25(OH)D with hypothesized explanatory factors were estimated in women at delivery (n = 655) and 6 mo postpartum (n = 566), and in their infants at birth (n = 502) and 6 mo of age (n = 215). Base models included initial 25(OH)D and supplemental vitamin D dose. Multivariable models were extended to include other individual characteristics and specimen-related factors. The model coefficient of determination (R2) was used to express the percentage of total variance explained.

RESULTS

Supplemental vitamin D intake and initial 25(OH)D accounted for the majority of variance in maternal 25(OH)D at delivery and postpartum (R2 = 70% and 79%, respectively). Additional characteristics, including BMI, contributed negligibly to remaining variance (<5% increase in R2). Variance in neonatal 25(OH)D was explained mostly by maternal delivery 25(OH)D and prenatal vitamin D intake (R2 = 82%). Variance in 25(OH)D in later infancy could only partly be explained by numerous biological, sociodemographic, and laboratory-related characteristics, including feeding practices (R2 = 43%).

CONCLUSIONS

Presupplementation 25(OH)D and vitamin D supplemental dose are the major determinants of the response to maternal prenatal vitamin D intake. Vitamin D dosing regimens to prevent maternal and infant vitamin D deficiency should take into consideration the mean 25(OH)D concentration of the target population.

Iron, iodine and vitamin D deficiencies during pregnancy: epidemiology, risk factors and developmental impacts

Micronutrient deficiency persists throughout the world, and although the burden is higher in low-resource settings, it is also prevalent in wealthy countries, a phenomenon termed 'hidden hunger'. Due to their high requirements for vitamins and minerals relative to their energy intake, young women and children are particularly vulnerable to hidden hunger. As they share several risk factors and impact on overlapping outcomes, we consider how deficiency of iron, iodine and vitamin D can have profound impacts on perinatal health and infant development. We review the epidemiology of these micronutrient deficiencies during pregnancy, including social, environmental and dietary risk factors. We identify the main challenges in defining nutritional status of these nutrients using validated diagnostic criteria linked with meaningful clinical outcomes. Public health strategies are urgently required to improve the overall health and nutritional status of women of reproductive age. Obesity prevention and early detection of malnutrition with standardised screening methods would detect pregnant women at increased risk of iron deficiency. Development of sensitive, individual biomarkers of iodine status is required to protect maternal health and fetal/infant brain development. Risk assessments of vitamin D requirements during pregnancy need to be revisited from the perspective of fetal and neonatal requirements. International consensus on standardised approaches to micronutrient assessment, analysis and reporting as well as sensitive, clinically validated infant and child neuro-behavioural outcomes will enable progression of useful observational and intervention studies.

Maternal obesity and baseline vitamin D insufficiency alter the response to vitamin D supplementation: a double-blind, randomized trial in pregnant women

BACKGROUND

The achievement of target 25-hydroxyvitamin D [25(OH)D] concentrations in pregnancy may be altered by maternal obesity.

OBJECTIVE

The authors examined the effects of maternal supplementation of 10 μg compared with 20 μg vitamin D3/d on maternal and umbilical cord 25(OH)D. The secondary aim was to investigate the influence of maternal BMI (in kg/m2) on the response of the primary outcomes.

METHODS

The authors performed a 2-arm parallel double-blind randomized trial with 240 pregnant women recruited throughout the year in Northern Ireland. Women were stratified by BMI to receive 10 or 20 µg vitamin D3/d from 12 gestational wk (GW) until delivery. Maternal blood samples collected at 12, 28, and 36 GW and from the umbilical cord were analyzed for total serum 25(OH)D. A total of 166 women completed the study.

RESULTS

Mean ± SD 25(OH)D at 36 GW was 80.8 ± 28.2 compared with 94.4 ± 33.2 nmol/L (P < 0.001) (10 compared with 20 µg vitamin D3/d, respectively). In those classified with 25(OH)D <50 nmol/L at baseline and assigned 10 µg vitamin D3/d, mean 25(OH)D concentrations remained <50 nmol/L at 36 GW, whereas those <50 nmol/L at baseline and assigned 20 µg vitamin D3/d, had mean 25(OH)D concentrations ≥50 nmol/L at 28 and 36 GW. In women with obesity and 25(OH)D <50 nmol/L at baseline, the related mean umbilical cord 25(OH)D was deficient (<25 nmol/L) in both treatment groups, whereas those with obesity and 25(OH)D ≥50 nmol/L at baseline had an average umbilical cord 25(OH)D between 25 and 50 nmol/L in both treatment groups.

CONCLUSIONS

Supplementation of 20 µg vitamin D3/d is needed to attain maternal and umbilical cord 25(OH)D concentrations ≥50 nmol/L on average, in those who start pregnancy with low 25(OH)D concentrations (<50 nmol/L). Under current recommendations, women with obesity and low 25(OH)D in early pregnancy are particularly vulnerable to maintaining a low 25(OH)D concentration throughout pregnancy and having an infant born with deficient 25(OH)D concentrations. This trial was registered at ClinicalTrials.gov as NCT02713009.

Longitudinal Assessment of Vitamin D Status across Trimesters of Pregnancy

BACKGROUND

The evolution of vitamin D status across pregnancy trimesters and its association with prepregnancy body mass index (ppBMI; in kg/m2) remain unclear.

OBJECTIVES

We aimed to 1) assess trimester-specific serum total 25-hydroxyvitamin D [25(OH)D] concentrations, 2) compare those concentrations between ppBMI categories, and 3) examine associations between 25(OH)D concentrations, ppBMI, and vitamin D intake.

METHODS

As part of a prospective cohort study, 79 pregnant women with a mean age of 32.1 y and ppBMI of 25.7 kg/m2 were recruited in their first trimester (average 9.3 weeks of gestation). Each trimester, vitamin D intake was assessed by 3 Web-based 24-h recalls and a Web questionnaire on supplement use. Serum total 25(OH)D was measured by LC-tandem MS. Repeated-measures ANOVA was performed to assess the evolution of 25(OH)D concentrations across trimesters of pregnancy and comparisons of 25(OH)D concentrations between ppBMI categories were assessed by 1-factor ANOVAs. Stepwise regression analyses were used to identify determinants of 25(OH)D concentrations in the third trimester.

RESULTS

Mean ± SD serum total 25(OH)D concentrations increased across trimesters, even after adjustments for ppBMI, seasonal variation, and vitamin D intake from supplements (67.5 ± 20.4, 86.5 ± 30.9, and 88.3 ± 29.0 nmol/L at mean ± SD 12.6 ± 0.8, 22.5 ± 0.8, and 33.0 ± 0.6 weeks of gestation, respectively; P < 0.0001). In the first and third trimesters, women with a ppBMI ≥30 had lower serum total 25(OH)D concentrations than women with a ppBMI <25 (P < 0.05); however, most had concentrations >40nmol/L by the second trimester. Vitamin D intake from supplements was the strongest determinant of third-trimester serum total 25(OH)D concentrations (r2 = 0.246, β = 0.51; P < 0.0001).

CONCLUSIONS

There was an increase in serum total 25(OH)D concentrations across trimesters, independent of ppBMI, seasonal variation, and vitamin D intake from supplements. Almost all women had serum total 25(OH)D concentrations over the 40- and 50-nmol/L thresholds, thus our study supports the prenatal use of a multivitamin across pregnancy.

Vitamin D status and association with gestational diabetes mellitus in a pregnant cohort in Iceland

Background

Vitamin D deficiency has been associated with an increased risk of gestational diabetes mellitus (GDM), one of the most common pregnancy complications. The vitamin D status has never previously been studied in pregnant women in Iceland.

Objective

The aim of this research study was to evaluate the vitamin D status of an Icelandic cohort of pregnant women and the association between the vitamin D status and the GDM incidence.

Design

Subjects included pregnant women (n = 938) who attended their first ultrasound appointment, during gestational weeks 11-14, between October 2017 and March 2018. The use of supplements containing vitamin D over the previous 3 months, height, pre-pregnancy weight, and social status were assessed using a questionnaire, and blood samples were drawn for analyzing the serum 25‑hydroxyvitamin D (25OHD) concentration. Information regarding the incidence of GDM later in pregnancy was collected from medical records.

Results

The mean ± standard deviation of the serum 25OHD (S-25OHD) concentration in this cohort was 63±24 nmol/L. The proportion of women with an S-25OHD concentration of ≥ 50 nmol/L (which is considered adequate) was 70%, whereas 25% had concentrations between 30 and 49.9 nmol/L (insufficient) and 5% had concentrations < 30 nmol/L (deficient). The majority of women (n = 766, 82%) used supplements containing vitamin D on a daily basis. A gradual decrease in the proportion of women diagnosed with GDM was reported with increasing S-25OHD concentrations, going from 17.8% in the group with S-25OHD concentrations < 30 nmol/L to 12.8% in the group with S-25OHD concentrations ≥75 nmol/L; however, the association was not significant (P for trend = 0.11).

Conclusion

Approximately one-third of this cohort had S-25OHD concentrations below adequate levels (< 50 nmol/L) during the first trimester of pregnancy, which may suggest that necessary action must be taken to increase their vitamin D levels. No clear association was observed between the vitamin D status and GDM in this study.

Sex differences in requirements for micronutrients across the lifecourse

For many people, micronutrient requirement means the amount needed in the diet to ensure adequacy. Dietary reference values (DRV) provide guidance on the daily intake of vitamins and minerals required to ensure the needs of the majority in the population are covered. These are developed on estimates of the quantity of each micronutrient required by the average person, the bioavailability of the micronutrient from a typical diet and the interindividual variability in these amounts. Sex differences are inherent in the requirements for many micronutrients because they are influenced by body size or macronutrient intake. These are reflected in different DRV for males and females for some micronutrients, but not all, either when data from males and females are combined or when there is no evidence of sex differences. Pregnancy and lactation represent times when micronutrient requirements for females may differ from males, and separate DRV are provided. For some micronutrients, no additional requirement is indicated during pregnancy and lactation because of physiological adaptations. To date, little account has been taken of more subtle sex differences in growth and maturation rates, health vulnerabilities and in utero and other programming effects. Over the years, the MRC Nutrition and Bone Health Group has contributed data on micronutrient requirements across the lifecourse, particularly for calcium and vitamin D, and shown that supplementation can have unexpected sex-specific consequences that require further investigation. The present paper outlines the current issues and the need for future research on sex differences in micronutrient requirements.

Associations between maternal vitamin D status during three trimesters and cord blood 25(OH)D concentrations in newborns: a prospective Shanghai birth cohort study

PURPOSE

Prenatal vitamin D (VitD) deficiency influences children's health in later life. We aimed to test the associations between maternal VitD status in each of the three trimesters of pregnancy and cord blood 25(OH)D concentrations in newborns.

METHODS

Participants were pregnant women recruited from the Shanghai Birth Cohort (SBC) (n = 1100). Of all the participants, 946 completed the collection of venous blood at early (< 16 weeks, T1), mid- (24-28 weeks, T2), and late (32-34 weeks, T3) pregnancy as well as the corresponding cord blood in the newborns. Maternal serum 25(OH)D concentrations were measured by LC-MS/MS, and the information on confounding factors was obtained through a standardized questionnaire.

RESULTS

The mean 25(OH)D concentrations at time points T1, T2, T3 in maternal blood and cord blood of the newborns were 26.31 ng/mL, 31.92 ng/mL, 35.62 ng/mL, and 19.77 ng/mL, respectively. Neonatal 25(OH)D level in cord blood was positively correlated with maternal serum 25(OH)D levels at each trimester, and the strongest correlation was found at time point T3.

CONCLUSION

Maternal 25(OH)D concentrations at each trimester were positively associated with neonatal VitD status in cord blood, and the strongest correlation was found in the late stage of pregnancy, which could be considered as a sensitive time window. Attention should be paid to the nutritional status of VitD during pregnancy to better prevent the VitD deficiency in neonates.

Vitamin D Concentrations at Term Do Not Differ in Newborns and Their Mothers with and without Polycystic Ovary Syndrome

Studies suggest that non-pregnant women with polycystic ovary syndrome (PCOS) may be at elevated risk of 25 hydroxyvitamin D (25(OH)D) deficiency. Furthermore, there is evidence suggesting that 25(OH)D may also play an important role during pregnancy. Data regarding 25(OH)D deficiency during pregnancy in PCOS patients and its association with perinatal outcome is scarce. The aim of the study was to investigate whether mothers with and without PCOS have different 25(OH)D levels at term, how maternal 25(OH)D levels are reflected in their offspring, and if 25(OH)D levels are associated with an adverse perinatal outcome. Therefore, we performed a cross-sectional observational study and included 79 women with PCOS according to the ESHRE/ASRM 2003 definition and 354 women without PCOS and an ongoing pregnancy ≥ 37 + 0 weeks of gestation who gave birth in our institution between March 2013 and December 2015. Maternal serum and cord blood 25(OH)D levels were analyzed at the day of delivery. Maternal 25(OH)D levels did not differ significantly in women with PCOS and without PCOS (p = 0.998), nor did the 25(OH)D levels of their respective offspring (p = 0.692). 25(OH)D deficiency (<20 ng/mL) was found in 26.9% and 22.5% of women with and without PCOS (p = 0.430). There was a strong positive correlation between maternal and neonatal 25(OH)D levels in both investigated groups (r ≥ 0.79, p < 0.001). Linear regression estimates of cord blood 25(OH)D levels are about 77% of serum 25(OH)D concentrations of the mother. Compared to healthy controls, the risk for maternal complications was increased in PCOS women (48% vs. 65%; p = 0.009), while there was no significant difference in neonatal complications (22% and 22%; p = 1.0). However, 25(OH)D levels were similar between mothers and infants with and without perinatal complications. Although the share of women and infants with 25(OH)D deficiency was high in women with PCOS and without PCOS, it seems that the incidence of adverse perinatal outcome was not affected. The long-term consequences for mothers and infants with a 25(OH)D deficiency have to be investigated in future studies.

Failure of national antenatal vitamin D supplementation programme puts dark skinned infants at highest risk: A newborn bloodspot screening study

OBJECTIVES

To determine the prevalence of vitamin D deficiency on dried blood spots (DBS) obtained at newborn blood spot screening (NBS) and thereby test the efficacy of the UK national antenatal supplementation programme in an increasingly ethnically diverse English population. To evaluate the seasonal and ethnic variation in neonatal plasma 25 hydoxyvitamin D (25OHD) and its determinants.

DESIGN

Three thousand random DBS samples received at a single regional newborn screening laboratory (52° N) over two one-week periods, one in winter (February 2019) and one in summer (August 2019), were collected. Data was collected from NBS cards on birth weight, gestational age, maternal age, ethnicity, and post code which was replaced with index of multiple deprivation (IMD). 25OHD concentrations were measured on 6 mm sub-punch from DBS using quantitative liquid chromatography tandem mass spectrometry adjusted to equivalent plasma values. 25OHD variation with season was assessed using Mann-Whitney U test and ethnic groups compared using Kruskal-Wallis test. Linear regression was used to assess the determinants of 25OHD concentrations.

RESULTS

25OHD measurements were available in 2999 (1580 males) subjects [1499 winter-born and 1500 summer-born]. The majority were white British (59.1%) and born at term (mean ± SD gestational age of 38.8 ± 1.8 weeks) with a mean (±SD) birth weight of 3306 (±565) grams. The overall prevalence of vitamin D deficiency [25OHD<30 nmol/L (12 μg/L)] was 35.7% (n = 1070) and insufficiency [30-50 nmol/L (12-20 μg/L)] 33.7% (n = 1010). The median (IQR) 25OHD concentration was significantly lower in the winter-born compared to summer-born [29.1 (19.8, 40.6) vs 49.2 (34.3, 64.8) nmol/L respectively; p < 0.001]. Across both seasons, when compared to white British babies (41.6 nmol/L), the median 25OHD concentrations were significantly lower in babies of black (30.3 nmol/L; p < 0.001), Asian (31.3 nmol/L; p < 0.001), any other mixed (32.9 nmol/L; p < 0.001), mixed white and black (33.7 nmol/L; p < 0.05) and any other white (37.7 nmol/L; p < 0.05) ethnicity. The proportion of deficiency was also higher in babies of Asian (48%), black (47%) and mixed ethnicity (38-44%) compared to any other white (34%) or white British (30%) ethnicity. Season of birth, ethnicity, gestation and maternal age accounted for almost 24% of the variation in 25OHD concentrations.

CONCLUSION

The current UK antenatal supplementation programme fails to protect newborns from vitamin D deficiency, especially those from minority ethnic groups who are at high risk of vitamin D deficiency. Nearly 70% of all newborns and 85% of winter-borns had 25OHD concentrations below 50 nmol/L (20 μg/L). Almost 50% of babies of Black or Asian origin were deficient at birth, which explains their high risk of hypocalcaemic complications and rickets if left unsupplemented. Our findings call for an immediate review of the delivery of antenatal and infant vitamin D supplementation programmes and implementation of food fortification in the long term.

Vitamin D supplementation for term breastfed infants to prevent vitamin D deficiency and improve bone health

BACKGROUND

Vitamin D deficiency is common worldwide, contributing to nutritional rickets and osteomalacia which have a major impact on health, growth, and development of infants, children and adolescents. Vitamin D levels are low in breast milk and exclusively breastfed infants are at risk of vitamin D insufficiency or deficiency.

OBJECTIVES

To determine the effect of vitamin D supplementation given to infants, or lactating mothers, on vitamin D deficiency, bone density and growth in healthy term breastfed infants.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to 29 May 2020 supplemented by searches of clinical trials databases, conference proceedings, and citations.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs in breastfeeding mother-infant pairs comparing vitamin D supplementation given to infants or lactating mothers compared to placebo or no intervention, or sunlight, or that compare vitamin D supplementation of infants to supplementation of mothers.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial eligibility and risk of bias and independently extracted data. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included 19 studies with 2837 mother-infant pairs assessing vitamin D given to infants (nine studies), to lactating mothers (eight studies), and to infants versus lactating mothers (six studies). No studies compared vitamin D given to infants versus periods of infant sun exposure. Vitamin D supplementation given to infants: vitamin D at 400 IU/day may increase 25-OH vitamin D levels (MD 22.63 nmol/L, 95% CI 17.05 to 28.21; participants = 334; studies = 6; low-certainty) and may reduce the incidence of vitamin D insufficiency (25-OH vitamin D < 50 nmol/L) (RR 0.57, 95% CI 0.41 to 0.80; participants = 274; studies = 4; low-certainty). However, there was insufficient evidence to determine if vitamin D given to the infant reduces the risk of vitamin D deficiency (25-OH vitamin D < 30 nmol/L) up till six months of age (RR 0.41, 95% CI 0.16 to 1.05; participants = 122; studies = 2), affects bone mineral content (BMC), or the incidence of biochemical or radiological rickets (all very-low certainty). We are uncertain about adverse effects including hypercalcaemia. There were no studies of higher doses of infant vitamin D (> 400 IU/day) compared to placebo. Vitamin D supplementation given to lactating mothers: vitamin D supplementation given to lactating mothers may increase infant 25-OH vitamin D levels (MD 24.60 nmol/L, 95% CI 21.59 to 27.60; participants = 597; studies = 7; low-certainty), may reduce the incidences of vitamin D insufficiency (RR 0.47, 95% CI 0.39 to 0.57; participants = 512; studies = 5; low-certainty), vitamin D deficiency (RR 0.15, 95% CI 0.09 to 0.24; participants = 512; studies = 5; low-certainty) and biochemical rickets (RR 0.06, 95% CI 0.01 to 0.44; participants = 229; studies = 2; low-certainty). The two studies that reported biochemical rickets used maternal dosages of oral D3 60,000 IU/day for 10 days and oral D3 60,000 IU postpartum and at 6, 10, and 14 weeks. However, infant BMC was not reported and there was insufficient evidence to determine if maternal supplementation has an effect on radiological rickets (RR 0.76, 95% CI 0.18 to 3.31; participants = 536; studies = 3; very low-certainty). All studies of maternal supplementation enrolled populations at high risk of vitamin D deficiency. We are uncertain of the effects of maternal supplementation on infant growth and adverse effects including hypercalcaemia. Vitamin D supplementation given to infants compared with supplementation given to lactating mothers: infant vitamin D supplementation compared to lactating mother supplementation may increase infant 25-OH vitamin D levels (MD 14.35 nmol/L, 95% CI 9.64 to 19.06; participants = 269; studies = 4; low-certainty). Infant vitamin D supplementation may reduce the incidence of vitamin D insufficiency (RR 0.61, 95% CI 0.40 to 0.94; participants = 334; studies = 4) and may reduce vitamin D deficiency (RR 0.35, 95% CI 0.17 to 0.72; participants = 334; studies = 4) but the evidence is very uncertain. Infant BMC and radiological rickets were not reported and there was insufficient evidence to determine if maternal supplementation has an effect on infant biochemical rickets. All studies enrolled patient populations at high risk of vitamin D deficiency. Studies compared an infant dose of vitamin D 400 IU/day with varying maternal vitamin D doses from 400 IU/day to > 4000 IU/day. We are uncertain about adverse effects including hypercalcaemia.

AUTHORS' CONCLUSIONS

For breastfed infants, vitamin D supplementation 400 IU/day for up to six months increases 25-OH vitamin D levels and reduces vitamin D insufficiency, but there was insufficient evidence to assess its effect on vitamin D deficiency and bone health. For higher-risk infants who are breastfeeding, maternal vitamin D supplementation reduces vitamin D insufficiency and vitamin D deficiency, but there was insufficient evidence to determine an effect on bone health. In populations at higher risk of vitamin D deficiency, vitamin D supplementation of infants led to greater increases in infant 25-OH vitamin D levels, reductions in vitamin D insufficiency and vitamin D deficiency compared to supplementation of lactating mothers. However, the evidence is very uncertain for markers of bone health. Maternal higher dose supplementation (≥ 4000 IU/day) produced similar infant 25-OH vitamin D levels as infant supplementation of 400 IU/day. The certainty of evidence was graded as low to very low for all outcomes.

Newborn micronutrient status biomarkers in a cluster-randomized trial of antenatal multiple micronutrient compared with iron folic acid supplementation in rural Bangladesh

BACKGROUND

Daily antenatal multiple micronutrient (MM) compared with iron folic acid (IFA) supplementation from early pregnancy improved birth outcomes and maternal micronutrient status in rural Bangladesh, but effects on newborn status are unknown.

OBJECTIVE

We examined cord blood micronutrient biomarkers in relation to antenatal MM and IFA supplementation and maternal gestational micronutrient status in rural Bangladeshi newborns.

DESIGN

In a double-blinded, cluster-randomized trial of antenatal IFA or MM (with the same IFA content), we analyzed cord blood plasma from 333 singleton births, and corresponding maternal plasma at 32.5 ± 2.6 wk of gestation, for ferritin (iron stores), folate, cobalamin (vitamin B-12), retinol (vitamin A), 25-hydroxyvitamin D [25(OH)D, vitamin D status], α-tocopherol (vitamin E), zinc, thyroglobulin, and free thyroxine (iodine status). Intervention effects and associations were determined using linear regression, exploring maternal status as a mediator of intervention effects on cord biomarkers.

RESULTS

The MM intervention increased cord ferritin (mean: +12.4%; 95% CI: 1.3, 24.6%), 25(OH)D (mean: +14.7%; 95% CI: 4.8, 25.6%), and zinc (mean: +5.8%; 95% CI: 1.0, 10.8%). Cord folate (mean: +26.8%; 95% CI: 19.6, 34.5%), cobalamin (mean: +31.3%; 95% CI: 24.6, 38.3%), 25(OH)D (mean: +26.7%; 95% CI: 23.2, 30.3%), α-tocopherol (mean: +8.7%; 95% CI: 3.6, 13.7%), zinc (mean: +2.3%; 95% CI: 0.5, 4.2%), thyroglobulin (mean: +20.1%; 95% CI: 9.0, 32.2%) and thyroxine (mean: +1.5%; 95% CI: 0.0, 3.0%) increased per 1-SD increment in maternal status (all P < 0.05); ferritin and retinol changed by +2.0%; 95% CI: -8.9, 14.3%; P = 0.72; and +3.5%; 95% CI: -0.4, 7.3%; P = 0.07, respectively. Ferritin, folate, cobalamin, zinc, and thyroglobulin averaged 1.57-6.75 times higher and retinol, α-tocopherol, and 25(OH)D 0.30-0.84 times lower in cord than maternal plasma, suggesting preferential maternal-fetal transfer of iron, folate, cobalamin, and zinc; limited transfer of fat-soluble vitamins; and high fetal iodine demand.

CONCLUSIONS

Antenatal MM supplementation increased newborn ferritin, 25(OH)D, and zinc, while maternal and newborn folate, vitamins B-12, D, and E, zinc, and iodine biomarkers were positively related. Despite limited effects of MM, better maternal micronutrient status was associated with improved micronutrient status of Bangladeshi newborns. This trial was registered at clinicaltrials.gov as NCT00860470.

Diet in pregnant women that delivered prematurely and preterm newborn's bone status

OBJECTIVES

Inadequate maternal dietary pattern has been associated to negative pregnancy and fetal outcomes. With this study, we aimed to evaluate the adequacy of diet in pregnant women that delivered prematurely and its possible correlations with bone status of preterm newborns.

STUDY DESIGN

We prospectively enrolled women who delivered prematurely (≤than 34 gestational weeks) and their newborns (Neonatal Intensive Care, University Hospital of Padova) from January 2017 to May 2018. Maternal nutritional status and diet supplementations were assessed using a validated questionnaire. The preterm newborns were evaluated with anthropometric measurements and bone status by Quantitative Ultrasound of the second metacarpal bone within 72 h from birth.

RESULTS

One hundred and eighty mothers and 202 preterm newborns were evaluated. The mothers assumed more calories, proteins, total lipids and simple sugars compared to the revised National Guidelines. The intake of calcium, phosphorus and Vitamin D was inadequate despite the use of multivitamin supplements. The mothers assumption of vitamin D and zinc positively correlated with bone status and mothers with very low intake of vitamin D during gestation (<7 µg/die) had preterm newborns with a worst bone status at birth compared to those with a better intake (>7 µg/die).

CONCLUSIONS

Nutrition of pregnant women could be improved and maternal intakes of Vitamin D and zinc positively correlated with preterm newborn's bone status.

Validation and Determination of 25(OH) Vitamin D and 3-Epi25(OH)D3 in Breastmilk and Maternal- and Infant Plasma during Breastfeeding

Vitamin D deficiency in pregnant women and their offspring may result in unfavorable health outcomes for both mother and infant. A 25hydroxyvitamin D (25(OH)D) level of at least 75 nmol/L is recommended by the Endocrine Society. Validated, automated sample preparation and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were used to determine the vitamin D metabolites status in mother-infant pairs. Detection of 3-Epi25(OH)D3 prevented overestimation of 25(OH)D3 and misclassification of vitamin D status. Sixty-three percent of maternal 25(OH)D plasma levels were less than the recommended level of 25(OH)D at 3 months. Additionally, breastmilk levels of 25(OH)D decreased from 60.1 nmol/L to 50.0 nmol/L between six weeks and three months (p < 0.01). Furthermore, there was a positive correlation between mother and infant plasma levels (p < 0.01, r = 0.56) at 3 months. Accordingly, 31% of the infants were categorized as vitamin D deficient (25(OH)D < 50 nmol/L) compared to 25% if 3-Epi25(OH)D3 was not distinguished from 25(OH)D3. This study highlights the importance of accurate quantification of 25(OH)D. Monitoring vitamin D metabolites in infant, maternal plasma, and breastmilk may be needed to ensure adequate levels in both mother and infant in the first 6 months of infant life.

Vitamin D in pregnancy: Where we are and where we should go

Vitamin D deficiency has been widely reported among pregnant women and infants around the world. Women with low sun exposure, high BMI, low vitamin D intakes and socioeconomic disadvantage with poor quality diets are at greatest risk of vitamin D deficiency, leading to very low serum concentrations of 25-hydroxyvitamin D (25(OH)D) in their offspring and an increased risk of nutritional rickets. Many observational studies, supported by compelling in vitro and in vivo data, have generated evidence suggesting that low vitamin D status in pregnancy may also contribute to the risk of adverse perinatal outcomes including hypertensive disorders (e.g., preeclampsia), fetal growth restriction, and preterm birth. However, the few large randomized controlled trials (RCTs) conducted to date have generated conflicting evidence for a role of vitamin D supplementation in improving perinatal outcomes. Vitamin D supplementation policies during pregnancy and implementation of policies vary within and between jurisdictions. Regulatory authorities have cited insufficient evidence to establish pregnancy-specific targets for serum 25(OH)D concentrations or prenatal vitamin D intake that effectively reduce the risks of adverse perinatal and infant outcomes. This paper arises from a Debate on Vitamin D Requirements during Pregnancy, held at the 22nd Vitamin D Workshop, 2019. From varied perspectives, our objectives were to evaluate the evidence for: vitamin D metabolism in pregnancy and the prevalence of gestational vitamin D deficiency worldwide; the translation of laboratory research findings to clinical studies on the role of vitamin D in perinatal health; the challenges of designing and conducting clinical trials to establish prenatal vitamin D requirements; and results to date of major large RCTs of prenatal vitamin D supplementation. Lastly, we explored potential next steps towards generating robust clinical data in this field to address both public health protection and patient care.

Severe vitamin D deficiency in preterm infants: possibly no association with clinical outcomes?

Purpose: The primary objective of this study was to compare clinical outcomes of very low birth weight (VLBW) infants with 25-hydroxy vitamin D [25(OH)D] levels <25 nmol/l in umbilical cord blood versus VLBW infants with 25(OH)D levels in cord blood >25 nmol/l. The secondary objective was to evaluate umbilical cord vitamin D as a risk factor for respiratory distress syndrome (RDS) in preterm infants.Methods: We examined 25(OH)D levels in umbilical cord blood and in infants' serum at discharge from the neonatal intensive care unit. We evaluated the associations between severe vitamin D deficiency and various laboratory findings and clinical outcomes.Results: Eighty one infants with birth weight less than 1500 g met the entry criteria for this study and were divided to groups according to umbilical cord blood vitamin D [Group A: 25(OH)D < 25 nmol/l; 10 ng/ml and Group B: 25(OH)D > 25 nmol/l; 10 ng/ml]. Overall, 81.5% of the infants had a 25(OH)D level <50 nmol/L and 44.4% had a level <25 nmol/L. The laboratory findings and the subsequent clinical outcomes were comparable in infants in both groups (non-significant difference). Only the infants in the 25(OH)D 25 nmol/L group had a lower calcium in urine at age 28 d (p=.0272). In addition, we found in this study that umbilical cord vitamin D level does not lead to a higher or lower risk of RDS (odds ratio 1.044; 95% confidence interval 0.349-0.88; p=.0771).Conclusions: In our prospective cohort study, we found no significant association between vitamin D status and selected clinical outcomes when using a cut-off of 25 nmol/l (severe vitamin D deficiency) in preterm infants.

Variation in plasma 25-hydroxyvitamin D2 and D3 in normal pregnancy with gestational age, sampling season, and complications: A longitudinal cohort study

Introduction

Low levels of vitamin D in pregnancy have been associated with the risk of a variety of pregnancy outcomes. Few studies have investigated vitamin D concentrations throughout pregnancy in healthy women, and most guidelines recommend high vitamin D levels. In the present study, we investigated 25-hydroxyvitamin D concentrations in healthy Caucasian Danish women in relation to season, gestational age and possible vitamin D-linked complications.

Materials and methods

Eight hundred and one healthy Caucasian Danish women with an expected normal pregnancy were recruited among 2147 women attending first trimester screening. Seven blood samplings were planned throughout the pregnancy and delivery period. The 25-hydroxyvitamin D2 (25(OH)D2) and 25-hydroxyvitamin D3 (25(OH)D3) concentrations were measured by LC-MS/MS and total 25-hydroxyvitamin D (25(OH)D) were calculated.

Results

A total of 3304 samples from 694 women were available for 25(OH)D measurements. The mean (25^th-75^th percentiles) concentrations of 25(OH)D, 25(OH)D3, and 25(OH)D2 were 54.6 (38.8–68.6) nmol/L, 52.2 (36.4–66.4) nmol/L, and 2.4 (2.2–2.2) nmol/L, respectively. Season was the strongest predictor of 25(OH)D concentration, with the lowest values observed in winter and spring, where only 42% and 41% of samples, respectively, were above 50 nmol/L. Nearly all women had values below the suggested optimal level of 75 nmol/L, independent of season. 25(OH)D peaked at gestational weeks 21–34. Plasma 25(OH)D2 levels were low in all seasons. Women with complications during pregnancy had higher 25(OH)D (estimated difference 9.8 nmol/L, standard error 2.7, p<0.001) than did women without complications, and women giving birth vaginally had lower 25(OH)D than did those delivering via elective (10.0 nmol/L, standard error 2.1, p<0.001) or emergency cesarean section (6.8 nmol/L, standard error 2.2, p<0.001).

Conclusion

The 25(OH)D concentrations vary with both season and gestational age. Healthy women had lower 25(OH)D concentrations than recommended, without an association with an increased risk of pregnancy complications. Guidelines for vitamin D in pregnancy may require revision.

Summer Season and Recommended Vitamin D Intake Support Adequate Vitamin D Status throughout Pregnancy in Healthy Canadian Women and Their Newborns

BACKGROUND

Vitamin D deficiency in pregnancy is reported as a prevalent public health problem.

OBJECTIVES

We aimed to evaluate, in pregnant Canadian women, 1) vitamin D intake, 2) maternal and cord serum 25-hydroxycholecalciferol [25(OH)D] and maternal 1,25-dihydroxycholecalciferol [1,25(OH)2D], and 3) factors associated with maternal serum 25(OH)D.

METHODS

Women (n = 187; mean prepregnancy BMI 24.4 kg/m2, mean age 31 y) recruited to the Be Healthy in Pregnancy study provided fasting blood samples and nutrient intake at 12-17 (early) and 36-38 (late) weeks of gestation, and cord blood. Vitamin D intakes (Nutritionist Pro™) and serum 25(OH)D and 1,25(OH)2D concentrations (LC-tandem MS) were measured.

RESULTS

Vitamin D intake was comparable in early and late pregnancy [median (IQR) = 586 (459, 859) compared with 689 (544, 974) IU/d; P = 0.83], with 71% consumed as supplements. Serum 25(OH)D was significantly higher in late pregnancy (mean ± SD: 103.1 ± 29.3 nmol/L) than in early pregnancy (82.5 ± 22.5 nmol/L; P < 0.001) and no vitamin D deficiency (<30 nmol/L) occurred. Serum 1,25(OH)2D concentrations were significantly higher in late pregnancy (101.1 ± 26.9 pmol/L) than in early pregnancy (82.2 ± 19.2 pmol/L, P < 0.001, n = 84). Cord serum 25(OH)D concentrations averaged 55% of maternal concentrations. In adjusted multivariate analyses, maternal vitamin D status in early pregnancy was positively associated with summer season (est.β: 13.07; 95% CI: 5.46, 20.69; P < 0.001) and supplement intake (est.β: 0.01; 95% CI: 0.00, 0.01; P < 0.001); and in late pregnancy with summer season (est.β: 24.4; 95% CI: 15.6, 33.2; P < 0.001), nonmilk dairy intake (est.β: 0.17; 95% CI: 0.02, 0.32; P = 0.029), and supplement intake (est.β: 0.01; 95% CI: 0.00, 0.01; P = 0.04).

CONCLUSIONS

Summer season and recommended vitamin D intakes supported adequate vitamin D status throughout pregnancy and in cord blood at >50 nmol/L in healthy Canadian pregnant women. This trial was registered at clinicaltrials.gov as NCT01693510.

Vitamin D Status Increases During Pregnancy and in Response to Vitamin D Supplementation in Rural Gambian Women

BACKGROUND

Vitamin D is important to maternal, fetal, and infant health, but quality data on vitamin D status in low- and middle-income countries and response to cholecalciferol supplementation in pregnancy are sparse.

OBJECTIVE

We characterized vitamin D status and vitamin D metabolite change across pregnancy and in response to cholecalciferol supplementation in rural Gambia.

METHODS

This study was a secondary analysis of samples collected in a 4-arm trial of maternal nutritional supplementation [iron folic acid (FeFol); multiple micronutrients (MMN); protein energy (PE) as lipid-based supplement; PE + MMN]; MMN included 10 μg/d cholecalciferol. Plasma 25-hydroxycholecalciferol [25(OH)D3], 24,25-dihydroxycholecalciferol [24,25(OH)2D3], and C3-epimer-25-hydroxycholecalciferol [3-epi-25(OH)D3] were measured by LC-MS/MS in 863 women [aged 30 ± 7 y (mean ± SD)] in early pregnancy (presupplementation) and late pregnancy, (gestational age 14 ± 3 and 30 ± 1 wk). Changes in 25(OH)D3 and vitamin D metabolite concentrations and associations with pregnancy stage and maternal age and anthropometry were tested.

RESULTS

Early pregnancy 25(OH)D3 concentration was 70 ± 15 nmol/L and increased according to pregnancy stage (82 ± 18 and 87 ± 17 nmol/L in the FeFol and PE-arms) and to cholecalciferol supplementation (95 ± 19 and 90 ± 20 nmol/L in the MMN and PE + MMN-arms) (P < 0.0001). There was no difference between supplemented groups. Early pregnancy 25(OH)D3 was positively associated with maternal age and gestational age. Change in 25(OH)D3 was negatively associated with late pregnancy, but not early pregnancy, triceps skinfold thickness. The pattern of change of 24,25(OH)2D3 mirrored that of 25(OH)D3 and appeared to flatten as pregnancy progressed, whereas 3-epi-25(OH)D3 concentration increased across pregnancy.

CONCLUSION

This study provides important data on the vitamin D status of a large cohort of healthy pregnant women in rural Africa. Without supplementation, vitamin D status increased during pregnancy, demonstrating that pregnancy stage should be considered when assessing vitamin D status. Nutritionally relevant cholecalciferol supplementation further increased vitamin D status. These data are relevant to the development of fortification and supplementation policies in pregnant women in West Africa.

Vitamin D Supplementation during Pregnancy: An Evidence Analysis Center Systematic Review and Meta-Analysis

BACKGROUND

Given the high rates of vitamin D deficiency among pregnant women and possible effects on offspring health, a systematic review on this topic was conducted to help inform future practice guidelines.

OBJECTIVE

To evaluate associations between maternal vitamin D supplementation, maternal 25-hydroxyvitamin D (25(OH)D) concentrations, and health outcomes.

METHODS

A PubMed literature search was conducted to identify studies that examined the health effects of vitamin D supplementation during pregnancy on maternal and infant health outcomes published from 2000 to 2016. Among 976 identified publications, 20 randomized clinical trials met the inclusion criteria. The initial search was extended to include five studies published between July 2016 and September 2018.

MAIN OUTCOME MEASURES

Maternal and infant 25(OH)D concentrations, gestational diabetes, preeclampsia or gestational hypertension, cesarean section, maternal parathyroid hormone and calcium concentrations, and infant gestational age, birth weight, and birth length.

STATISTICAL ANALYSES

Mean differences, odds ratios, and 95% CIs were calculated, only for the initial search, using separate random-effects meta-analyses for each outcome.

RESULTS

Evidence was good or strong that maternal vitamin D supplementation significantly increased maternal (13 studies, n=18, mean difference, 14.1 ng/mL [35.2 nmol/L]; 95% CI=9.6-18.6 ng/mL [24.0-46.4 nmol/L]) and infant (nine studies, n=12; 9.7, 5.2, 14.2 ng/mL [24.2, 12.9, 35.5 nmol/L]) 25(OH)D concentrations, although heterogeneity was significant (I²=95.9% and I²=97.4, respectively, P<0.001). Evidence was fair that vitamin D supplementation significantly decreases maternal homeostatic model assessment-insulin resistance (five studies, n=7; -1.1, -1.5, -0.7) and increases infant birth weight (nine studies, n=11, 114.2, 63.4, 165.1 g), both had insignificant heterogeneity. A null effect of maternal supplementation on other maternal (preeclampsia, cesarean section) and infant (gestational age, birth length) outcomes was found.

CONCLUSIONS

Results show vitamin D supplementation during pregnancy improves maternal and infant 25(OH)D concentrations and may play a role in maternal insulin resistance and fetal growth. To further inform practice and policies on the amount of vitamin D, which supports a healthy pregnancy, high quality dose-response randomized clinical trials, which assess pregnancy-specific 25(OH)D thresholds, and appropriately powered clinical outcomes are needed.

Regimens of vitamin D supplementation for women during pregnancy

BACKGROUND

Vitamin D deficiency during pregnancy increases the risk of pre-eclampsia, gestational diabetes, preterm birth, and low birthweight. In a previous Cochrane Review we found that supplementing pregnant women with vitamin D alone compared to no vitamin D supplementation may reduce the risk of pre-eclampsia, gestational diabetes, and low birthweight and may increase the risk of preterm births if it is combined with calcium. However the effects of different vitamin D regimens are not yet clear.

OBJECTIVES

To assess the effects and safety of different regimens of vitamin D supplementation alone or in combination with calcium or other vitamins, minerals or nutrients during pregnancy, specifically doses of 601 international units per day (IU/d) or more versus 600 IU/d or less; and 4000 IU/d or more versus 3999 IU/d or less.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (12 July 2018), and the reference lists of retrieved studies.

SELECTION CRITERIA

Randomised trials evaluating the effect of different vitamin D regimens (dose, frequency, duration, and time of commencement of supplementation during pregnancy), alone or in combination with other nutrients on pregnancy and neonatal health outcomes. We only included trials that compared 601 IU/d or more versus 600 IU/d or less and 4000 IU/d or more versus 3999 IU/d or less. We did not include in the analysis groups that received no vitamin D, as that comparison is assessed in another Cochrane Review.

DATA COLLECTION AND ANALYSIS

Two review authors independently: i) assessed the eligibility of studies against the inclusion criteria; ii) extracted data from included studies, and iii) assessed the risk of bias of the included studies. Our primary maternal outcomes were: pre-eclampsia, gestational diabetes, and any adverse effects; our primary infant outcomes were preterm birth and low birthweight. Data were checked for accuracy. The certainty of the evidence was assessed using the GRADE approach.

MAIN RESULTS

In this review, we included data from 30 trials involving 7289 women. We excluded 11 trials, identified 16 ongoing/unpublished trials and two trials are awaiting classification. Overall risk of bias for the trials was mixed.Comparison 1. 601 IU/d or more versus 600 IU/d or less of vitamin D alone or with any other nutrient (19 trials; 5214 participants)Supplementation with 601 IU/d or more of vitamin D during pregnancy may make little or no difference to the risk of pre-eclampsia (risk ratio (RR) 0.96, 95% confidence interval (CI) 0.65 to 1.42); 5 trials; 1553 participants,low-certainty evidence), may reduce the risk of gestational diabetes (RR 0.54, 95% CI 0.34 to 0.86; 5 trials; 1846 participants; moderate-certainty evidence), may make little or no difference to the risk of preterm birth (RR 1.25, 95% CI 0.92 to 1.69; 4 trials; 2294 participants; low-certainty evidence); and may make little or no difference to the risk of low birthweight (RR 0.90, 95% CI 0.66 to 1.24; 4 trials; 1550 participants; very low-certainty evidence) compared to women receiving 600 IU/d or less.Comparison 2. 4000 IU or more versus 3999 IU or less of vitamin D alone (15 trials; 4763 participants)Supplementation with 4000 IU/d or more of vitamin D during pregnancy may make little or no difference to the risk of: pre-eclampsia (RR 0.87, 95% CI 0.62 to 1.22; 4 trials, 1903 participants, low-certainty evidence); gestational diabetes (RR 0.89, 95% CI 0.56 to 1.42; 5 trials, 2276 participants; low-certainty evidence); preterm birth (RR 0.85, 95% CI 0.64 to 1.12; 6 trials, 2948 participants, low-certainty evidence); and low birthweight (RR 0.92, 95% CI 0.49 to 1.70; 2 trials; 1099 participants; low-certainty evidence) compared to women receiving 3999 IU/d or less.Adverse events (such as hypercalcaemia, hypocalcaemia, hypercalciuria, and hypovitaminosis D) were reported differently in most trials; however, in general, there was little to no side effects reported or similar cases between groups.

AUTHORS' CONCLUSIONS

Supplementing pregnant women with more than the current vitamin D recommendation may reduce the risk of gestational diabetes; however, it may make little or no difference to the risk of pre-eclampsia, preterm birth and low birthweight. Supplementing pregnant women with more than the current upper limit for vitamin D seems not to increase the risk of the outcomes evaluated. In general, the GRADE was considered low certainty for most of the primary outcomes due to serious risk of bias and imprecision of results. With respect to safety, it appears that vitamin D supplementation is a safe intervention during pregnancy, although the parameters used to determine this were either not reported or not consistent between trials. Future trials should be consistent in their reports of adverse events. There are 16 ongoing trials that when published, will increase the body of knowledge.

Vitamin D supplementation for women during pregnancy

BACKGROUND

Vitamin D supplementation during pregnancy may be needed to protect against adverse pregnancy outcomes. This is an update of a review that was first published in 2012 and then in 2016.

OBJECTIVES

To examine whether vitamin D supplementation alone or in combination with calcium or other vitamins and minerals given to women during pregnancy can safely improve maternal and neonatal outcomes.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register (12 July 2018), contacted relevant organisations (15 May 2018), reference lists of retrieved trials and registries at clinicaltrials.gov and WHO International Clinical Trials Registry Platform (12 July 2018). Abstracts were included if they had enough information to extract the data.

SELECTION CRITERIA

Randomised and quasi-randomised trials evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy in comparison to placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently i) assessed the eligibility of trials against the inclusion criteria, ii) extracted data from included trials, and iii) assessed the risk of bias of the included trials. The certainty of the evidence was assessed using the GRADE approach.

MAIN RESULTS

We included 30 trials (7033 women), excluded 60 trials, identified six as ongoing/unpublished trials and two trials are awaiting assessments.Supplementation with vitamin D alone versus placebo/no interventionA total of 22 trials involving 3725 pregnant women were included in this comparison; 19 trials were assessed as having low-to-moderate risk of bias for most domains and three trials were assessed as having high risk of bias for most domains. Supplementation with vitamin D alone during pregnancy probably reduces the risk of pre-eclampsia (risk ratio (RR) 0.48, 95% confidence interval (CI) 0.30 to 0.79; 4 trials, 499 women, moderate-certainty evidence) and gestational diabetes (RR 0.51, 95% CI 0.27 to 0.97; 4 trials, 446 women, moderate-certainty evidence); and probably reduces the risk of having a baby with low birthweight (less than 2500 g) (RR 0.55, 95% CI 0.35 to 0.87; 5 trials, 697 women, moderate-certainty evidence) compared to women who received placebo or no intervention. Vitamin D supplementation may make little or no difference in the risk of having a preterm birth < 37 weeks compared to no intervention or placebo (RR 0.66, 95% CI 0.34 to 1.30; 7 trials, 1640 women, low-certainty evidence). In terms of maternal adverse events, vitamin D supplementation may reduce the risk of severe postpartum haemorrhage (RR 0.68, 95% CI 0.51 to 0.91; 1 trial, 1134 women, low-certainty evidence). There were no cases of hypercalcaemia (1 trial, 1134 women, low-certainty evidence), and we are very uncertain as to whether vitamin D increases or decreases the risk of nephritic syndrome (RR 0.17, 95% CI 0.01 to 4.06; 1 trial, 135 women, very low-certainty evidence). However, given the scarcity of data in general for maternal adverse events, no firm conclusions can be drawn.Supplementation with vitamin D and calcium versus placebo/no interventionNine trials involving 1916 pregnant women were included in this comparison; three trials were assessed as having low risk of bias for allocation and blinding, four trials were assessed as having high risk of bias and two had some components having a low risk, high risk, or unclear risk. Supplementation with vitamin D and calcium during pregnancy probably reduces the risk of pre-eclampsia (RR 0.50, 95% CI 0.32 to 0.78; 4 trials, 1174 women, moderate-certainty evidence). The effect of the intervention is uncertain on gestational diabetes (RR 0.33,% CI 0.01 to 7.84; 1 trial, 54 women, very low-certainty evidence); and low birthweight (less than 2500 g) (RR 0.68, 95% CI 0.10 to 4.55; 2 trials, 110 women, very low-certainty evidence) compared to women who received placebo or no intervention. Supplementation with vitamin D and calcium during pregnancy may increase the risk of preterm birth < 37 weeks in comparison to women who received placebo or no intervention (RR 1.52, 95% CI 1.01 to 2.28; 5 trials, 942 women, low-certainty evidence). No trial in this comparison reported on maternal adverse events.Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D)One trial in 1300 participants was included in this comparison; it was assessed as having low risk of bias. Pre-eclampsia was not assessed. Supplementation with vitamin D + other nutrients may make little or no difference in the risk of preterm birth < 37 weeks (RR 1.04, 95% CI 0.68 to 1.59; 1 trial, 1298 women, low-certainty evidence); or low birthweight (less than 2500 g) (RR 1.12, 95% CI 0.82 to 1.51; 1 trial, 1298 women, low-certainty evidence). It is unclear whether it makes any difference to the risk of gestational diabetes (RR 0.42, 95% CI 0.10 to 1.73) or maternal adverse events (hypercalcaemia no events; hypercalciuria RR 0.25, 95% CI 0.02 to 3.97; 1 trial, 1298 women,) because the certainty of the evidence for both outcomes was found to be very low.

AUTHORS' CONCLUSIONS

We included 30 trials (7033 women) across three separate comparisons. Our GRADE assessments ranged from moderate to very low, with downgrading decisions based on limitations in study design, imprecision and indirectness.Supplementing pregnant women with vitamin D alone probably reduces the risk of pre-eclampsia, gestational diabetes, low birthweight and may reduce the risk of severe postpartum haemorrhage. It may make little or no difference in the risk of having a preterm birth < 37 weeks' gestation. Supplementing pregnant women with vitamin D and calcium probably reduces the risk of pre-eclampsia but may increase the risk of preterm births < 37 weeks (these findings warrant further research). Supplementing pregnant women with vitamin D and other nutrients may make little or no difference in the risk of preterm birth < 37 weeks' gestation or low birthweight (less than 2500 g). Additional rigorous high quality and larger randomised trials are required to evaluate the effects of vitamin D supplementation in pregnancy, particularly in relation to the risk of maternal adverse events.

Serum 25-Hydroxyvitamin D Concentrations at Birth in Children Screened for HLA-DQB1 Conferred Risk for Type 1 Diabetes

CONTEXT

Vitamin D has several effects on the immune system that might be of relevance for the pathogenesis of type 1 diabetes (T1D).

OBJECTIVE

To evaluate whether umbilical cord serum concentrations of 25-hydroxy-vitamin D (25[OH]D) differ in children developing either islet autoimmunity (IA) or overt T1D during childhood and adolescence.

DESIGN

Umbilical cord serum samples from 764 children born from 1994 to 2004 with HLA-DQB1 conferred risk for T1D participating in the Type 1 Diabetes Prediction and Prevention Study were analyzed for 25(OH)D using an enzyme immunoassay.

SETTING

DIPP clinics in Turku, Oulu, and Tampere University Hospitals, Finland.

PARTICIPANTS

Two hundred fifty children who developed T1D diabetes at a median age of 6.7 years (interquartile range [IQR] 4.0 to 10.1 years) and 132 additional case children who developed IA, i.e., positivity for multiple islet autoantibodies. Cases were matched for date of birth, gender, and area of birth with 382 control children who remained autoantibody negative. The median duration of follow up was 9.8 years (IQR 5.7 to 13.1 years).

MAIN OUTCOME MEASURE

The median 25(OH)D concentrations.

RESULTS

The median 25(OH)D concentration in cord serum was low [31.1 nmol/L (IQR 24.0 to 41.8); 88% <50 nmol/L], but not statistically different between children who developed T1D or IA and their control groups (P = 0.70). The levels were associated mainly with geographical location, year and month of birth, age of the mother, and maternal intake of vitamin D during pregnancy.

CONCLUSIONS

The 25(OH)D concentrations at birth are not associated with the development of T1D during childhood.

Calcium

Calcium is the fifth most abundant element in the body with >99% residing in the skeleton as hydroxyapatite, a complex calcium phosphate molecule. This mineral supplies the strength to bones that support locomotion, but it also serves as a reservoir to maintain serum calcium concentrations. Calcium plays a central role in a wide range of essential functions. Its metabolism is regulated by 3 major transport systems: intestinal absorption, renal reabsorption, and bone turnover. Calcium transport in these tissues is regulated by a sophisticated homeostatic hormonal system that involves parathyroid hormone, and 1,25-dihydroxyvitamin D in response to decreased serum ionized calcium, detected by the calcium-sensing receptor (1).

Mineral Homeostasis in Murine Fetuses Is Sensitive to Maternal Calcitriol but Not to Absence of Fetal Calcitriol

Vitamin D receptor (VDR) null fetuses have normal serum minerals, parathyroid hormone (PTH), skeletal morphology, and mineralization but increased serum calcitriol, placental calcium transport, and placental expression of Pthrp, Trpv6, and (as reported in this study) Pdia3. We examined Cyp27b1 null fetal mice, which do not make calcitriol, to determine if loss of calcitriol has the same consequences as loss of VDR. Cyp27b1 null and wild-type (WT) females were mated to Cyp27b1^+/- males, which generated Cyp27b1 null and Cyp27b1^+/- fetuses from Cyp27b1 null mothers, and Cyp27b1^+/- and WT fetuses from WT mothers. Cyp27b1 null fetuses had undetectable calcitriol but normal serum calcium and phosphorus, PTH, fibroblast growth factor 23 (FGF23), skeletal mineral content, tibial lengths and morphology, placental calcium transport, and expression of Trpv6 and Pthrp; conversely, placental Pdia3 was downregulated. However, although Cyp27b1^+/- and null fetuses of Cyp27b1 null mothers were indistinguishable, they had higher serum and amniotic fluid calcium, lower amniotic fluid phosphorus, lower FGF23, and higher 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D than in WT and Cyp27b1^+/- fetuses of WT mothers. In summary, loss of fetal calcitriol did not alter mineral or bone homeostasis, but Cyp27b1 null mothers altered mineral homeostasis in their fetuses independent of fetal genotype. Cyp27b1 null fetuses differ from Vdr null fetuses, possibly through high levels of calcitriol acting on Pdia3 in Vdr nulls to upregulate placental calcium transport and expression of Trpv6 and Pthrp. In conclusion, maternal calcitriol influences fetal mineral metabolism, whereas loss of fetal calcitriol does not. © 2018 American Society for Bone and Mineral Research.

Vitamin D status of very low birth weight infants at birth and the effects of generally recommended supplementation on their vitamin D levels at discharge

Purpose: To evaluate vitamin D status in mothers and their very low birth weight infants (VLBW) at birth (umbilical cord blood) and at discharge with currently recommended supplementation of vitamin D.Methods: Ninety-four infants with birth weight less than 1500 g completed the study. The total daily vitamin D intake was 800-1000 IU. We examined 25-hydroxyvitamin-D [25(OH)D] levels in maternal serum before labor, in cord blood, and in infants' serum at discharge.Results: Median (IQR) serum 25(OH)D was 21 (14-36) nmol/l [8 (6-15) ng/ml] in cord blood, and 46 (37-60) nmol/l [18 (15-24) ng/ml] at discharge. Serum 25(OH)D was <50 nmol/L in 71.3% of mothers, in 91.5% of cord blood samples, and in almost 60% of preterm newborns at discharge (after 8 weeks of supplementation). Serum 25(OH)D was <75 nmol/L in 88.3% of mothers, in 97.9% of cord blood samples, and in 91.4% of preterm newborns at discharge.Conclusions: In our cohort, we found that due to the very high prevalence of 25(OH)D deficiency among mothers, the current generally recommended dose of vitamin D (800-1000 IU per day) for VLBW infants was unable to improve vitamin D levels above the desired 50 or even 75 nmol/L before discharge.

Contribution of nutrition science to the vitamin D field-Clarity or confusion?

Recent opinion pieces have questioned whether nutrition science is fit for purpose, suggesting that the evidence-base for dietary recommendations is populated with poor quality science and unresolved controversy. Nutrition science is accused of not keeping up with the times and making little real-world progress to stem the growing global malnutrition crisis, by failing to apply cutting-edge techniques to nutrition problems. Nutritional epidemiology has been blamed for harming public health nutrition and the public perception of science itself, by selectively reporting biased, confounded data. Focussed on obesity and associated disorders and hunger, these articles do not refer to micronutrient deficiencies or advances in micronutrient research. There is a serious public health problem of low vitamin D status. Given that the field of vitamin D has experienced an exponential increase in peer-reviewed publications over the last 50 years, it seems timely that we take these cues to reflect upon whether the expanded body of scientific literature has contributed to a deeper knowledge of vitamin D in health and disease, leading to improved nutrition policy and patient care, or whether it has led to so much confusion and controversy that progress has been impeded. We consider whether the accusations of poor science and biased reporting levelled at nutrition science are evident within the vitamin D nutrition research area and whether they have compromised dietary recommendations for vitamin D. In evaluating whether reformation is required, we discuss the confusion and controversy within the field and signpost common ground within the vitamin D community. We outline vitamin D nutrition research that has presented strategies for vitamin D deficiency prevention within the population, particularly using food first approaches that could extend beyond high income settings to low- and middle-income countries. Finally, we encourage government and industry to implement technical advances and drive real-world progress.

Serum 25-hydroxyvitamin D response to vitamin D supplementation in infants: a systematic review and meta-analysis of clinical intervention trials

PURPOSE

For the prevention of nutritional rickets, 400 IU vitamin D daily and circulating 25-hydroxyvitamin D (25OHD) concentrations > 50 nmol/L are recommended, whereas the toxicity threshold is set at 250 nmol/L. We synthesized the evidence for the effect of vitamin D supplementation on incremental 25OHD in infants up to 1 year of age.

METHODS

We performed a systematic review and meta-analysis of intervention trials in several databases. A total of 87 records were identified for full-text review and 27 articles with 61 studies were included in the final analysis.

RESULTS

The selected 61 studies included 1828 participants. Nineteen cohorts had already mean baseline 25OHD levels ≥ 50 nmol/L. The weighted mean difference in 25OHD following vitamin D supplementation was + 49.4 nmol/L (95% CI 43.6-55.3 nmol/L; P < 0.001). The increment was dose-dependent (P = 0.002), was higher in full-term than in pre-term infants (P < 0.001), was higher in infants with baseline 25OHD < 50 nmol/L as compared to ≥ 50 nmol/L (P = 0.001), and was marginally influenced by the 25OHD test procedure (P = 0.080). Vitamin D₃ doses of 400 IU/day were sufficient to achieve 25OHD concentrations ≥ 50 nmol/L in most full-term infants. A 25OHD level of 250 nmol/L was not exceeded in ≥ 97.5% of infants at doses between 200 and 1200 IU/day, but potentially in ≥ 2.5% of infants at a dose of 1600 IU/day.

CONCLUSIONS

Vitamin D supplementation of 400 IU/day is sufficient for achieving 25OHD concentrations able to prevent nutritional rickets. A more personalized vitamin D dosing strategy would require 25OHD testing, but also assay standardization.

Vitamin D testing and treatment: a narrative review of current evidence

Vitamin D testing and treatment is a subject of controversial scientific discussions, and it is challenging to navigate through the expanding vitamin D literature with heterogeneous and partially opposed opinions and recommendations. In this narrative review, we aim to provide an update on vitamin D guidelines and the current evidence on the role of vitamin D for human health with its subsequent implications for patient care and public health issues. Vitamin D is critical for bone and mineral metabolism, and it is established that vitamin D deficiency can cause rickets and osteomalacia. While many guidelines recommend target serum 25-hydroxyvitamin D (25[OH]D) concentrations of ≥50 nmol/L (20 ng/mL), the minimum consensus in the scientific community is that serum 25(OH)D concentrations below 25-30 nmol/L (10-12 ng/mL) must be prevented and treated. Using this latter threshold of serum 25(OH)D concentrations, it has been documented that there is a high worldwide prevalence of vitamin D deficiency that may require public health actions such as vitamin D food fortification. On the other hand, there is also reason for concern that an exploding rate of vitamin D testing and supplementation increases costs and might potentially be harmful. In the scientific debate on vitamin D, we should consider that nutrient trials differ from drug trials and that apart from the opposed positions regarding indications for vitamin D treatment we still have to better characterize the precise role of vitamin D for human health.