Vitamin D in pregnancy-time for action: a paediatric audit

Effects of vitamin D on bone density in healthy children: A systematic review

Skeletal growth and bone health are very important in children. The effective role of vitamin D in bone mineral density has been observed in children and adolescents. This systematic review study evaluated the effects of vitamin D on bone density in healthy children with the help of valid databases and the website of clinical trials. The results of experimental, clinical, retrospective, prospective, double-blind, and randomized studies were used. Articles that appropriately covered the topic and had the proper content structure were selected for this review. Out of a total of 132 articles, finally, 13 articles were selected based on inclusion and exclusion criteria for further study, the results of which show the association between serum levels of vitamin D and bone mineral density and health. However, in some articles, the relationship between other influential variables such as age and nutrition on bone density in children was identified. In general, the current systematic review demonstrates the role of vitamin D on bone density in healthy children, so that in children studied, vitamin D is at different levels and complications related to bone density are observed in many children. It is recommended that more clinical and longitudinal studies be performed to further understand the role of vitamin D levels in bone health in children.

Maternal vitamin D status in preeclampsia: seasonal changes are not influenced by placental gene expression of vitamin D metabolizing enzymes

Preeclampsia, a hypertensive disorder in pregnancy develops in 2–8% of pregnancies worldwide. Winter season and vitamin D deficiency have been associated with its onset.

Objective

To investigate the influence of season on maternal vitamin D status and placental vitamin D metabolism.

Methods

25-OH vitamin D and 1,25-(OH)₂ vitamin D were measured in maternal serum obtained during the winter or summer months from 63 pregnant women at delivery (43 healthy, 20 preeclampsia). In a subgroup, mRNA expression of CYP24A1 (24-hydroxylase), CYP27B1 (1α-hydroxylase) and VDR (vitamin D receptor) were quantified by real time PCR in placental samples of 14 women with normal pregnancies and 13 with preeclampsia.

Results

In patients with preeclampsia,25-OH vitamin D levels were lower, but differed significantly from controls only in summer (18.21±17.1 vs 49.2±29.2 ng/mL, P<0.001), whereas 1,25-(OH)₂ vitamin D levels were significantly lower only in winter (291±217 vs 612.3±455 pmol/mL, P<0.05). A two-factorial analysis of variance produced a statistically significant model (P<0.0001) with an effect of season (P<0.01) and preeclampsia (P = 0.01) on maternal 25-OH vitamin D levels, as well as a significant interaction between the two variables (P = 0.02). Placental gene expression of CYP24A1, CYP27B1, and VDR did not differ between groups or seasons. A negative correlation between placental gene expression of CYP24A1 and CYP27B1 was observed only in healthy controls (r = −0.81, P<0.0001).

Summary

Patients with preeclampsia displayed lower vitamin D serum levels in response to seasonal changes.The regulation of placental CYP24A1, but not of the VDR or CYP27B1 might be altered in preeclampsia.

Maternal vitamin D status in pregnancy and offspring bone development: the unmet needs of vitamin D era

Data from animal and human studies implicate maternal vitamin D deficiency during pregnancy as a significant risk factor for several adverse outcomes affecting maternal, fetal, and child health. The possible associations of maternal vitamin D status and offspring bone development comprise a significant public health issue. Evidence from randomized trials regarding maternal vitamin D supplementation for optimization of offspring bone mass is lacking. In the same field, data from observational studies suggest that vitamin D supplementation is not indicated. Conversely, supplementation studies provided evidence that vitamin D has beneficial effects on neonatal calcium homeostasis. Nevertheless, a series of issues, such as technical difficulties of current vitamin D assays and functional interplay among vitamin D analytes, prohibit arrival at safe conclusions. Future studies would benefit from adoption of a gold standard assay, which would unravel the functions of vitamin D analytes. This narrative review summarizes and discusses data from both observational and supplementation studies regarding maternal vitamin D status during pregnancy and offspring bone development.

The effect of cigarette smoke exposure on vitamin D level and biochemical parameters of mothers and neonates

BACKGROUND

Exposure to cigarette smoke during pregnancy leads to several adverse effects on mother and child. The purpose of this study was to evaluate the effect of being a passive smoker during pregnancy on vitamin D level and related biochemical indices including parathyroid hormone, calcium, phosphorus and alkaline phosphatase in mothers and newborns.

METHODS

One hundred eight pregnant women and their newborns participated in a historical cohort study in two equal groups (n = 54) with and without cigarette smoke exposure. Maternal blood and urine samples and blood samples of umbilical cord were obtained in the delivery room. Concentration of 25-hydroxy vitamin D and related biochemical indices in samples of maternal and cord blood were investigated. Exposure to cigarette smoke was evaluated through questionnaire and maternal urine and umbilical cord serum cotinine levels.

RESULTS

The mean level of 25-hydroxyvitamin D in maternal serum was 9.28 ± 5.19 ng/mlin exposed and 10.75 ± 5.26 ng/ml in non-exposed group(p > 0.05). The mean concentration of 25-hydroxy vitamin D in cord serum was 10.83 ± 6.68 ng/ml in the exposed and 11.05 ± 4.99 ng/ml in the non-exposed group(p > 0.05). The exposed mothers had significantly higher parathyroid hormone level (p = 0.013), lower serum calcium (p = 0.024) and higher serum alkaline phosphatase (p = 0.024). There was a significant correlation between maternal and umbilical cord serum 25-hydroxyvitamin D within both exposed and non-exposed groups (p < 0.001).

CONCLUSION

Maternal exposure to cigarette smoking during pregnancy negatively influences serum calcium level and increase parathyroid hormone and alkaline phosphatase in mothers.

Prevalence of vitamin D deficiency in a North London antenatal population

OBJECTIVE

We evaluated the prevalence of vitamin D deficiency in the antenatal patients attending North Middlesex University Hospital between March 2008 and March 2009.

STUDY DESIGN

A prospective study of maternal levels of vitamin D at booking.

RESULTS

The prevalence of both deficient and insufficient levels of 25[OH]D was 87.6% across all included patients.

CONCLUSION

There is a high prevalence of asymptomatic vitamin D deficiency in the antenatal booking population.

Effects of vitamin D supplementation on bone density in healthy children: systematic review and meta-analysis

OBJECTIVE

To determine the effectiveness of vitamin D supplementation for improving bone mineral density in children and adolescents and if effects vary with factors such as vitamin D dose and vitamin D status.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Cochrane Central Register of Controlled Trials, Medline (1966 to present), Embase (1980 to present), CINAHL (1982 to present), AMED (1985 to present), and ISI Web of Science (1945 to present), last updated on 9 August 2009, and hand searching of conference abstracts from key journals. Study selection Placebo controlled randomised controlled trials of vitamin D supplementation for at least three months in healthy children and adolescents (aged 1 month to <20 years) with bone density outcomes. Two authors independently assessed references for inclusion and study quality and extracted data.

DATA SYNTHESIS

Standardised mean differences of the percentage change from baseline in bone mineral density of the forearm, hip, and lumbar spine and total body bone mineral content in treatment and control groups. Subgroup analyses were carried out by sex, pubertal stage, dose of vitamin D, and baseline serum vitamin D concentration. Compliance and allocation concealment were also considered as possible sources of heterogeneity.

RESULTS

From 1653 potential references, six studies, totalling 343 participants receiving placebo and 541 receiving vitamin D, contributed data to meta-analyses. Vitamin D supplementation had no statistically significant effects on total body bone mineral content or on bone mineral density of the hip or forearm. There was a trend to a small effect on lumbar spine bone mineral density (standardised mean difference 0.15, 95% confidence interval -0.01 to 0.31; P=0.07). Effects were similar in studies of participants with high compared with low serum vitamin D levels, although there was a trend towards a larger effect with low vitamin D for total body bone mineral content (P=0.09 for difference). In studies with low serum vitamin D, significant effects on total body bone mineral content and lumbar spine bone mineral density were roughly equivalent to a 2.6% and 1.7% percentage point greater change from baseline in the supplemented group.

CONCLUSIONS

It is unlikely that vitamin D supplements are beneficial in children and adolescents with normal vitamin D levels. The planned subgroup analyses by baseline serum vitamin D level suggest that vitamin D supplementation of deficient children and adolescents could result in clinically useful improvements, particularly in lumbar spine bone mineral density and total body bone mineral content, but this requires confirmation.

A randomized, controlled trial of vitamin D supplementation upon musculoskeletal health in postmenarchal females

CONTEXT

There has been a resurgence of vitamin D deficiency rickets throughout the developed world, with infants and adolescents being primarily affected. Adolescence is a crucial period for muscle and bone mineral accumulation.

OBJECTIVE

The aim was to determine the effect of vitamin D supplementation on the adolescent musculoskeletal system.

DESIGN AND SETTING

We conducted a community-based, double-blind, randomized controlled trial in a secondary school.

PARTICIPANTS

Postmenarchal 12- to 14-yr-old females participated in the trial. Ninety-nine were screened, 73 were included in randomized controlled trial, and 69 completed the trial. There were no adverse events.

INTERVENTION

Four doses of 150,000 IU vitamin D(2) (ergocalciferol) were given over 1 yr.

MAIN OUTCOME MEASURES

Dual-energy x-ray absorptiometry, peripheral quantitative computed tomography, and jumping mechanography were used.

RESULTS

At follow-up, 25-hydroxyvitamin D [25(OH)D] status was 56.0 ± 8.9 nmol/liter in the intervention group and 15.8 ± 6.6 nmol/liter in controls. There were no effects of supplementation on bone; however, for muscle function, efficiency of movement improved in the vitamin D-treated group. There was an interaction between baseline 25(OH)D concentration and response to vitamin D supplementation for muscle jump velocity.

CONCLUSIONS

Despite improvements in 25(OH)D status, treatment with vitamin D(2) was not shown to increase mineral accretion, bone geometry or strength, muscle force, or power. There were greater increases in jump velocity in girls with the lowest baseline 25(OH)D concentrations. Lack of effect of intervention after the period of peak mineral and muscle mass accretion suggests that earlier action is required.

Effect of multiple-micronutrient supplementation on maternal nutrient status, infant birth weight and gestational age at birth in a low-income, multi-ethnic population

Poor nutrient intake during pregnancy can adversely affect both infant and maternal health. The aim was to investigate the efficacy of multiple-micronutrient supplementation during pregnancy in a socially deprived population in the developed world. We conducted a randomised, double-blind, placebo-controlled trial of multiple-micronutrient supplementation including 20 mg Fe and 400 μg folic acid, from the first trimester of pregnancy in 402 mothers, in East London, UK. Nutrient status was measured at recruitment, and at 26 and 34 weeks of gestation. Infants were weighed at birth. At recruitment the prevalence of anaemia was 13 %, vitamin D insufficiency 72 %, thiamin deficiency 12 % and folate deficiency 5 %, with no differences between groups. Only 39 % of women completed the study; rates of non-compliance were similar in both groups. Intention-to-treat analysis showed that participants receiving treatment had higher mean Hb at 26 weeks of gestation (110 (sd10)v.108 (sd10) g/l;P = 0·041) and 34 weeks of gestation (113 (sd12)v.109 (sd10) g/l;P = 0·003) and packed cell volume concentrations at 26 weeks of gestation (0·330 (sd0·025)v.0·323 (sd0·026) l/l;P = 0·011) and 34 weeks of gestation (0·338 (sd0·029)v.0·330 (sd0·028) l/l;P = 0·014) compared with controls. Analysis of compliant women showed supplemented women had higher median concentrations of serum ferritin, erythrocyte folate and 25-hydroxyvitamin D later in gestation than controls. In the compliant subset (n149), placebo mothers had more small-for-gestational age (SGA) infants (eight SGAv.thirteen;P = 0·042) than treatment mothers. Baseline micronutrient deficiencies were common; the multiple-micronutrient supplement was well-tolerated and improved nutrient status. Multiple-micronutrient supplements from early pregnancy may be beneficial and larger studies are required to assess impact on birth outcomes and infant development.