Vitamin D supplements enhance weight gain and nutritional status in pregnant Asians

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We included 30 trials (7033 women), excluded 60 trials, identified six as ongoing/unpublished trials and two trials are awaiting assessments.Supplementation with vitamin D alone versus placebo/no interventionA total of 22 trials involving 3725 pregnant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.

High Prevalence of Vitamin D Deficiency among Iranian Population: A Systematic Review and Meta-Analysis

BACKGROUND

The prevention and correction of vitamin D deficiency requires a precise depiction of the current situation and identification of risk factors in each region. The present study attempted to determine these entities using a systematic review and meta-analysis in Iran.

METHODS

Articles published online in Persian and English between 2000 and November 1, 2016, were reviewed. This was carried out using national databases such as SID, IranMedex, Magiran, and IranDoc and international databases such as PubMed, Google Scholar, and Scopus. The heterogeneity index among the studies was determined using the Cochran (Q) and I² test. Based on the heterogeneity results, the random-effect model was applied to estimate the prevalence of vitamin D deficiency. In addition, meta-regression analysis was used to determine heterogeneity-suspected factors, and the Egger test was applied to identify publication bias.

RESULTS

The meta-analysis of 48 studies identified 18531 individuals with vitamin D deficiency. According to the random-effect model, the prevalence of vitamin D deficiency among male, female, and pregnant women was estimated to be 45.64% (95% CI: 29.63 to 61.65), 61.90% (95% CI: 48.85 to 74.96), and 60.45% (95% CI: 23.73 to 97.16), respectively. The results of the meta-regression analysis indicated that the prevalence of vitamin D deficiency was significantly different in various geographical regions (β=4.4; P=0.023).

CONCLUSION

The results obtained showed a significant prevalence of vitamin D deficiency among the Iranian population, a condition to be addressed by appropriate planning.

Effect of vitamin D supplementation in the reduce risk of preeclampsia in nulliparous women

Background:

The exact role of vitamin D in the development and severity of preeclampsia is still unclear. The aim of the present study was to investigate the association between vitamin D supplement and preeclampsia in pregnant women.

Materials and Methods:

In this randomized controlled trial, in 2012, 140 nulliparous pregnant women in two groups received supplementation with 600 IU/day of vitamin D or supplementation free of vitamin D at 16 week gestation until the delivery. The main outcomes included the frequency of preeclampsia and subtypes by clinical severity and infant birth weight.

Results:

Mean of maternal age and gestational age at the delivery in all studied subjects were 25 ± 4.1 years and 37.4 ± 3 weeks, respectively, which were not statistically significant between the groups. Preeclampsia was observed in two subjects in case group compared to seven subjects in control group, which was not significant (P-value = 0.09). In case group, subjects with preeclampsia diagnosed as mild preeclampsia and in control group four subjects were mild, and three were severe. No significant differences were noted between the case and control groups in the frequency of preeclampsia subtypes by clinical severity. Infant birth weight in case group who was significantly higher than control group, which was statistically significant between groups (P-value = 0.09).

Conclusion:

In summary, our results demonstrated that vitamin D supplementation during the third trimester of pregnancy; despite the non-significant association between vitamin D supplementation and preeclampsia, reduce the risk of preeclampsia. However, further studies needs to be done.

Vitamin D supplementation for women during pregnancy

BACKGROUND

Vitamin D deficiency or insufficiency is thought to be common among pregnant women. Vitamin D supplementation during pregnancy has been suggested as an intervention to protect against adverse pregnancy outcomes.

OBJECTIVES

To examine whether oral supplements with vitamin D 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

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (23 February 2015), the International Clinical Trials Registry Platform (31 January 2015), the Networked Digital Library of Theses and Dissertations (28 January 2015) and also contacted relevant organisations (31 January 2015).

SELECTION CRITERIA

Randomised and quasi-randomised trials with randomisation at either individual or cluster level, evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy.

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. Data were checked for accuracy. The quality of the evidence was assessed using the GRADE approach.

MAIN RESULTS

In this updated review we included 15 trials assessing a total of 2833 women, excluded 27 trials, and 23 trials are still ongoing or unpublished. Nine trials compared the effects of vitamin D alone versus no supplementation or a placebo and six trials compared the effects of vitamin D and calcium with no supplementation. Risk of bias in the majority of trials was unclear and many studies were at high risk of bias for blinding and attrition rates. Vitamin D alone versus no supplementation or a placebo Data from seven trials involving 868 women consistently show that women who received vitamin D supplements alone, particularly on a daily basis, had higher 25-hydroxyvitamin D than those receiving no intervention or placebo, but this response was highly heterogeneous. Also, data from two trials involving 219 women suggest that women who received vitamin D supplements may have a lower risk of pre-eclampsia than those receiving no intervention or placebo (8.9% versus 15.5%; risk ratio (RR) 0.52; 95% CI 0.25 to 1.05, low quality). Data from two trials involving 219 women suggest a similar risk of gestational diabetes among those taking vitamin D supplements or no intervention/placebo (RR 0.43; 95% CI 0.05, 3.45, very low quality). There were no clear differences in adverse effects, with only one reported case of nephritic syndrome in the control group in one study (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women, low quality). Given the scarcity of data for this outcome, no firm conclusions can be drawn. No other adverse effects were reported in any of the other studies.With respect to infant outcomes, data from three trials involving 477 women suggest that vitamin D supplementation during pregnancy reduces the risk preterm birth compared to no intervention or placebo (8.9% versus 15.5%; RR 0.36; 95% CI 0.14 to 0.93, moderate quality). Data from three trials involving 493 women also suggest that women who receive vitamin D supplements during pregnancy less frequently had a baby with a birthweight below 2500 g than those receiving no intervention or placebo (RR 0.40; 95% CI 0.24 to 0.67, moderate quality).In terms of other outcomes, there were no clear differences in caesarean section (RR 0.95; 95% CI 0.69 to 1.31; two trials; 312 women); stillbirths (RR 0.35 95% CI 0.06, 1.99; three trials, 540 women); or neonatal deaths (RR 0.27; 95% CI 0.04, 1.67; two trials, 282 women). There was some indication that vitamin D supplementation increases infant length (mean difference (MD) 0.70, 95% CI -0.02 to 1.43; four trials, 638 infants) and head circumference at birth (MD 0.43, 95% CI 0.03 to 0.83; four trials, 638 women). Vitamin D and calcium versus no supplementation or a placeboWomen who received vitamin D with calcium had a lower risk of pre-eclampsia than those not receiving any intervention (RR 0.51; 95% CI 0.32 to 0.80; three trials; 1114 women, moderate quality), but also an increased risk of preterm birth (RR 1.57; 95% CI 1.02 to 2.43, three studies, 798 women, moderate quality). Maternal vitamin D concentration at term, gestational diabetes, adverse effects and low birthweight were not reported in any trial or reported only by one study.

AUTHORS' CONCLUSIONS

New studies have provided more evidence on the effects of supplementing pregnant women with vitamin D alone or with calcium on pregnancy outcomes. Supplementing pregnant women with vitamin D in a single or continued dose increases serum 25-hydroxyvitamin D at term and may reduce the risk of pre-eclampsia, low birthweight and preterm birth. However, when vitamin D and calcium are combined, the risk of preterm birth is increased. The clinical significance of the increased serum 25-hydroxyvitamin D concentrations is still unclear. In light of this, these results need to be interpreted with caution. Data on adverse effects were lacking in all studies.The evidence on whether vitamin D supplementation should be given as a part of routine antenatal care to all women to improve maternal and infant outcomes remains unclear. While there is some indication that vitamin D supplementation could reduce the risk of pre-eclampsia and increase length and head circumference at birth, further rigorous randomised trials are required to confirm these effects.

Post-hoc comparison of vitamin D status at three timepoints during pregnancy demonstrates lower risk of preterm birth with higher vitamin D closer to delivery

There have been observational reports that maternal vitamin D status at baseline and not closest to delivery is a better predictor of pregnancy outcomes, suggesting that a cascade of events is set into motion that is not modifiable by vitamin D supplementation during later pregnancy. To address this issue, in this exploratory post-hoc analysis using correlation and logistic regression, we sought to measure the strength of the association between serum 25(OH)D concentrations at 3 timepoints during pregnancy: baseline, 1st trimester (<16 weeks); 2nd trimester (16-26 weeks); and 3rd trimester (≥27 weeks) and preterm birth. It was hypothesized that the 25(OH)D value closest to delivery would be most significantly associated with preterm birth. To accomplish this objective, the datasets from NICHD (n=333) and Thrasher Research Fund (n=154) vitamin D supplementation pregnancy studies were combined. The results of this analysis were that 25(OH)D values closer to delivery were more strongly correlated with gestational age at delivery than earlier values: 1st trimester: r=0.11 (p=0.02); 2nd trimester: r=0.08 (p=0.09); and 3rd trimester: r=0.15 (p=0.001). When logistic regression was performed with preterm birth (<37 weeks) as the outcome and 25(OH)D quartiles as the predictor variable, adjusting for study and participant race/ethnicity, as with the correlation analysis, the measurements closer to delivery were more significantly associated and had a higher magnitude of effect. That is, at baseline, those who had serum concentrations <50nmol/L (20ng/mL) had 3.3 times of odds of a preterm birth compared to those with serum concentrations ≥100nmol/L (40ng/mL; p=0.27). At 2nd trimester, the odds were 2.0 fold (p=0.21) and at the end of pregnancy, the odds were 3.8 fold (p=0.01). The major findings from this exploratory analysis were: (1) maternal vitamin D status closest to delivery date was more significantly associated with preterm birth, suggesting that later intervention as a rescue treatment may positively impact the risk of preterm delivery, and (2) a serum concentration of 100nmol/L (40ng/mL) in the 3rd trimester was associated with a 47% reduction in preterm births. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

The Effect of Vitamin D and Calcium plus Vitamin D during Pregnancy on Pregnancy and Birth Outcomes: a Randomized Controlled Trial

INTRODUCTION

Evidence suggests a high prevalence of calcium and vitamin D deficiencies exists in both pregnant women and babies. Adequate intake of micronutrients has great importance especially during pregnancy and lactation period. Thus, the present study aimed at assessing the effect of vitamin D and calcium-vitamin D on pregnancy and birth outcomes (including duration of pregnancy, type of delivery and infant anthropometric indicators).

METHODS

A randomized, controlled, clinical, triple-blind trial conducted on 126 pregnant women referring to Tabriz health centers in 2013-14. Subjects were allocated into three groups using block randomization. Interventional groups received vitamin D, calcium-vitamin D and placebo pills daily for 60 days. ANCOVA and Chi-square tests were used for data analysis.

RESULTS

By controlling BMI before and during pregnancy, there were no significant differences between the group in average neonatal weight, height and head circumference, duration of pregnancy, type of delivery and gestational age at the time of delivery.

CONCLUSION

The results show that calcium-vitamin D and vitamin D have no effect on duration of pregnancy, type of delivery and infant anthropometric indicators.

Building healthy bones throughout life: an evidence-informed strategy to prevent osteoporosis in Australia

Osteoporosis imposes a tremendous burden on Australia: 1.2 million Australians have osteoporosis and 6.3 million have osteopenia. In the 2007–08 financial year, 82 000 Australians suffered fragility fractures, of which > 17 000 were hip fractures. In the 2000–01 financial year, direct costs were estimated at $1.9 billion per year and an additional $5.6 billion on indirect costs. Osteoporosis was designated a National Health Priority Area in 2002; however, implementation of national plans has not yet matched the rhetoric in terms of urgency. Building healthy bones throughout life, the Osteoporosis Australia strategy to prevent osteoporosis throughout the life cycle, presents an evidence-informed set of recommendations for consumers, health care professionals and policymakers. The strategy was adopted by consensus at the Osteoporosis Australia Summit in Sydney, 20 October 2011. Primary objectives throughout the life cycle are: to maximise peak bone mass during childhood and adolescence to prevent premature bone loss and improve or maintain muscle mass, strength and functional capacity in healthy adults to prevent and treat osteoporosis in order to minimise the risk of suffering fragility fractures, and reduce falls risk, in older people. The recommendations focus on three affordable and important interventions — to ensure people have adequate calcium intake, vitamin D levels and appropriate physical activity throughout their lives. Recommendations relevant to all stages of life include: daily dietary calcium intakes should be consistent with Australian and New Zealand guidelines serum levels of vitamin D in the general population should be above 50nmol/L in winter or early spring for optimal bone health regular weight-bearing physical activity, muscle strengthening exercises and challenging balance/mobility activities should be conducted in a safe environment.

Bone development and mineral homeostasis in the fetus and neonate: roles of the calciotropic and phosphotropic hormones

Mineral and bone metabolism are regulated differently in utero compared with the adult. The fetal kidneys, intestines, and skeleton are not dominant sources of mineral supply for the fetus. Instead, the placenta meets the fetal need for mineral by actively transporting calcium, phosphorus, and magnesium from the maternal circulation. These minerals are maintained in the fetal circulation at higher concentrations than in the mother and normal adult, and such high levels appear necessary for the developing skeleton to accrete a normal amount of mineral by term. Parathyroid hormone (PTH) and calcitriol circulate at low concentrations in the fetal circulation. Fetal bone development and the regulation of serum minerals are critically dependent on PTH and PTH-related protein, but not vitamin D/calcitriol, fibroblast growth factor-23, calcitonin, or the sex steroids. After birth, the serum calcium falls and phosphorus rises before gradually reaching adult values over the subsequent 24-48 h. The intestines are the main source of mineral for the neonate, while the kidneys reabsorb mineral, and bone turnover contributes mineral to the circulation. This switch in the regulation of mineral homeostasis is triggered by loss of the placenta and a postnatal fall in serum calcium, and is followed in sequence by a rise in PTH and then an increase in calcitriol. Intestinal calcium absorption is initially a passive process facilitated by lactose, but later becomes active and calcitriol-dependent. However, calcitriol's role can be bypassed by increasing the calcium content of the diet, or by parenteral administration of calcium.

Knowledge, attitudes, and beliefs that can influence infant feeding practices in American Indian mothers

The promotion of healthy infant feeding is increasingly recognized as an important obesity-prevention strategy. This is relevant for American Indian populations that exhibit high levels of obesity and low compliance with infant feeding guidelines. The literature examining the knowledge, attitudes, and beliefs surrounding infant feeding within the American Indian population is sparse and focuses primarily on breastfeeding, with limited information on the introduction of solid foods and related practices that can be important in an obesity-prevention context. This research presents descriptive findings from a baseline knowledge, attitudes, and beliefs questionnaire on infant feeding and related behaviors administered to mothers (n=438) from five Northwest American Indian tribes that participated in the Prevention of Toddler Overweight and Teeth Health Study (PTOTS). Enrollment occurred during pregnancy or up to 6 months postpartum. The knowledge, attitudes, and beliefs questionnaire focused on themes of breastfeeding/formula feeding and introducing solid foods, with supplemental questions on physical activity. Knowledge questions were multiple choice or true/false. Attitudes and beliefs were assessed on Likert scales. Descriptive statistics included frequencies and percents and means and standard deviations. Most women knew basic breastfeeding recommendations and facts, but fewer recognized the broader health benefits of breastfeeding (eg, reducing diabetes risk) or knew when to introduce solid foods. Women believed breastfeeding to be healthy and perceived their social networks to agree. Attitudes and beliefs about formula feeding and social support were more ambivalent. This work suggests opportunities to increase the perceived value of breastfeeding to include broader health benefits, increase knowledge about solid foods, and strengthen social support.

Obstetric and neonatal outcomes of maternal vitamin D supplementation: results of an open-label, randomized controlled trial of antenatal vitamin D supplementation in Pakistani women

OBJECTIVE

The objective of the study was to determine whether vitamin D (vitD) supplementation during pregnancy affects obstetric and neonatal outcomes.

SETTING

The study was conducted at a university hospital in Karachi, Pakistan.

METHODS

The study was a single-center, open-label, randomized, controlled trial of routine care (group A, 200 mg ferrous sulfate and 600 mg calcium daily) vs vitD supplementation (group B, 4000 IU vitamin D3 daily), started at 20 weeks and continued till delivery. Maternal serum samples of 25-hydroxyvitamin D (25OHD) were collected at baseline and delivery. Neonatal vitD status was assessed in cord blood or in neonatal serum samples within 48 hours of birth. Obstetric outcomes included gestational hypertension, gestational diabetes, and preterm labor, and neonatal well-being included small for gestational age, birth weight, length, head circumference, and 1- and 5-minute Apgar scores.

RESULTS

Of 207 gravidae enrolled, 193 completed the trial. Maternal age, vitD status, and gestational age at enrollment were comparable between the two groups. At delivery, maternal 25OHD was increased in group B (18.3 ± 11 ng/dL vs 8.82 ± 11.84 ng/dL (P = .001) compared with group A (6.9 ± 7.0 ng/dL vs 6.32 ± 3.97 ng/dL, P = .06). The obstetric outcomes were comparable between the two groups (P > .05). Neonatal 25OHD levels were significantly higher in group B compared with group A (19.22 ± 12.19 ng/dL vs 6.27 ± 5.2 ng/dL). There was positive correlation between maternal and neonatal 25OHD levels (r = 0.83, P = .001). One- and 5-minute Apgar scores were significantly higher in group B (7.10 ± 0.66 vs 6.90 ± 0.50, P = .026, and 8.53 ± 0.68 vs 8.33 ± 0.81, P = .051, respectively). Neonatal anthropometric parameters were comparable between the two groups (P > .05).

CONCLUSION

Maternal vitD supplementation improved maternal and neonatal vitD status.

Health characteristics and outcomes of two randomized vitamin D supplementation trials during pregnancy: a combined analysis

OBJECTIVE

To assess the safety and health effects of vitamin D supplementation during pregnancy.

METHODS AND DESIGN

Datasets from two randomized clinical trials were first analyzed separately then combined for this analysis using a common data dictionary. In the NICHD trial, women were randomized to 400, 2000, or 4000IU vitamin D3/day, stratified by race. In the Thrasher Research Fund trial, participants were randomized to 2000 or 4000IU vitamin D3/day. Study drugs were from the same manufacturing lot for both trials. Identical questionnaires were given for comparable sociodemographics & clinical characteristics. Outcome measures were: [1] maternal and neonatal 25(OH)D achieved, and [2] maternal comorbidities of pregnancy (COP). SAS 9.3 was used for all analyses.

RESULTS

In the combined cohort, there were 110 controls, 201 in the 2000IU group, and 193 in the 4000IU group. No differences between groups in baseline 25(OH)D were found; however, delivery and cord blood values were greater in the 4000IU group (p<0.0001), an effect that persisted even after controlling for race and study. A greater percent were vitamin D replete in the 4000IU group (p<0.0001). There was a trend where the 4000IU group had decreased rates of comorbidities of pregnancy. There was a strong association between COP and final maternal 25(OH)D; an effect that persisted even after controlling for race and study (p=0.006).

CONCLUSIONS

Supplementation with 4000IU/day was associated with lower risk of hypovitaminosis D than Control and 2000IU groups. While not statistically significant, there was a trend toward lower rates of COP as supplementation dose increased. Maternal delivery 25(OH)D was inversely associated with any comorbidity of pregnancy, with fewer events as 25(OH)D increased. Future studies are needed to confirm these findings and determine the mechanisms of action of such effects. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Vitamin D effects on musculoskeletal health, immunity, autoimmunity, cardiovascular disease, cancer, fertility, pregnancy, dementia and mortality-a review of recent evidence

BACKGROUND

Optimal vitamin D intake and its status are important not only for bone and calcium-phosphate metabolism, but also for overall health and well-being. Vitamin D deficiency and insufficiency as a global health problem are likely to be a risk for wide spectrum of acute and chronic illnesses.

METHODS

A review of randomized controlled trials, meta-analyses, and other evidence of vitamin D action on various health outcomes.

RESULTS

Adequate vitamin D status seems to be protective against musculoskeletal disorders (muscle weakness, falls, fractures), infectious diseases, autoimmune diseases, cardiovascular disease, type 1 and type 2 diabetes mellitus, several types of cancer, neurocognitive dysfunction and mental illness, and other diseases, as well as infertility and adverse pregnancy and birth outcomes. Vitamin D deficiency/insufficiency is associated with all-cause mortality.

CONCLUSIONS

Adequate vitamin D supplementation and sensible sunlight exposure to reach optimal vitamin D status are among the front line factors of prophylaxis for the spectrum of disorders. Supplementation guidance and population strategies for the eradication of vitamin D deficiency must be included in the priorities of physicians, medical professionals and healthcare policy-makers.

Vitamin D and pregnancy: skeletal effects, nonskeletal effects, and birth outcomes

The function and requirement of vitamin D during pregnancy for both mother and fetus have remained a mystery. This fact was highlighted by The Cochrane Review in 2000, which reported a lack of randomized controlled trials (RCTs) with respect to vitamin D requirements during pregnancy. Unfortunately, during the past decade only a single RCT has been performed with respect to vitamin D requirements during pregnancy. In this review we will discuss vitamin D metabolism during pregnancy as well as the consequences of vitamin D deficiency on skeletal, nonskeletal, and birth outcomes using birth observational data and data from our recent RCT. New RCT data strongly support previous observational studies in that improving nutritional vitamin D status will improve birth outcomes. The new RCT data indicate that 4,000 IU/day vitamin D(3) during pregnancy will "normalize" vitamin D metabolism and improve birth outcomes including primary cesarean section and comorbidities of pregnancy with no risk of side effects.

A randomized trial of vitamin D supplementation in 2 community health center networks in South Carolina

OBJECTIVE

We sought to determine whether 4000 IU/d (vs 2000 IU/d) of vitamin D during pregnancy is safe and improves maternal/neonatal 25-hydroxyvitamin D [25(OH)D] in a dose-dependent manner.

STUDY DESIGN

A total of 257 pregnant women 12-16 weeks' gestation were enrolled. Randomization to 2000 vs 4000 IU/d followed 1-month run-in at 2000 IU/d. Participants were monitored for hypercalciuria, hypercalcemia, and 25(OH)D status.

RESULTS

Maternal 25(OH)D (n = 161) increased from 22.7 ng/mL (SD 9.7) at baseline to 36.2 ng/mL (SD 15) and 37.9 ng/mL (SD 13.5) in the 2000 and 4000 IU groups, respectively. While maternal 25(OH)D change from baseline did not differ between groups, 25(OH)D monthly increase differed between groups (P < .01). No supplementation-related adverse events occurred. Mean cord blood 25(OH)D was 22.1 ± 10.3 ng/mL in 2000 IU and 27.0 ± 13.3 ng/mL in 4000 IU groups (P = .024). After controlling for race and study site, preterm birth and labor were inversely associated with predelivery and mean 25(OH)D, but not baseline 25(OH)D.

CONCLUSION

Maternal supplementation with vitamin D 2000 and 4000 IU/d during pregnancy improved maternal/neonatal vitamin D status. Evidence of risk reduction in infection, preterm labor, and preterm birth was suggestive, requiring additional studies powered for these endpoints.

The role of vitamin D in pregnancy and lactation: emerging concepts

Pregnancy is a critical time in the lifecycle of a woman where she is responsible not only for her own well-being, but also that of her developing fetus, a process that continues during lactation. Until recently, the impact of vitamin D status during this period had not been fully appreciated. Data regarding the importance of vitamin D in health have emerged to challenge traditional dogma, and suggest that vitamin D - through its effect on immune function and surveillance - plays a role beyond calcium and bone metabolism on the health status of both the mother and her fetus. Following birth, this process persists; the lactating mother continues to be the main source of vitamin D for her infant. Thus, during both pregnancy and lactation, maternal deficiency predicts fetal and infant deficiency; the significance of this is just beginning to be understood and will be highlighted in this review.

Vitamin D during pregnancy and maternal, neonatal and infant health outcomes: a systematic review and meta-analysis

Vitamin D has well-defined classical functions related to calcium metabolism and bone health but also has non-classical effects that may influence other aspects of health. There has been considerable recent interest in the role of vitamin D on outcomes related to pregnancy and young child health but few efforts have been made to systematically consolidate this evidence to inform the research and policy agenda for low-income countries. A systematic review was undertaken to identify intervention and observational studies of vitamin D supplementation, intake or status (25-hydroxy-vitamin D) during pregnancy on perinatal and infant health outcomes. Data from trials and observational studies isolating the effect of vitamin D supplementation and intake were extracted and study quality was evaluated. Meta-analysis was used to pool effect estimates. We identified five randomised trials with outcomes of relevance to our review. All had small sample size and dosage amount, duration and frequency varied as did the ability to correct deficiency. Pooled analysis of trials using fixed-effects models suggested protective effects of supplementation on low birthweight (three trials, risk ratio (RR) = 0.40 [95% confidence interval (CI) 0.23, 0.71]) and non-significant but suggestive effects of daily supplementation on small-for-gestational age (two trials, RR = 0.67 [0.40, 1.11]). No effect on preterm delivery (<37 weeks) was evident (two trials, RR = 0.77 [0.35, 1.66]). Little evidence from trials exists to evaluate the effect of vitamin D supplementation during pregnancy on maternal, perinatal or infant health outcomes. Based on both trials and observational studies, we recommend that future research explore small-for-gestational age, preterm delivery, pre-eclampsia, and maternal and childhood infections, as outcomes of interest. Trials should focus on populations with a high prevalence of vitamin D deficiency, explore the relevance of timing of supplementation, and the dosage used in such trials should be sufficient to correct deficiency.

Vitamin D and its role during pregnancy in attaining optimal health of mother and fetus

Despite its discovery a hundred years ago, vitamin D has emerged as one of the most controversial nutrients and prohormones of the 21st century. Its role in calcium metabolism and bone health is undisputed but its role in immune function and long-term health is debated. There are clear indicators from in vitro and animal in vivo studies that point to vitamin D's indisputable role in both innate and adaptive immunity; however, the translation of these findings to clinical practice, including the care of the pregnant woman, has not occurred. Until recently, there has been a paucity of data from randomized controlled trials to establish clear cut beneficial effects of vitamin D supplementation during pregnancy. An overview of vitamin metabolism, states of deficiency, and the results of recent clinical trials conducted in the U.S. are presented with an emphasis on what is known and what questions remain to be answered.

Vitamin D supplementation for women during pregnancy

BACKGROUND

Vitamin D deficiency or insufficiency is thought to be common among pregnant women. Vitamin D supplementation during pregnancy has been suggested as an intervention to protect against adverse gestational outcomes.

OBJECTIVES

To examine whether supplements with vitamin D 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

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2011), the International Clinical Trials Registry Platform (ICTRP) (31 October 2011), the Networked Digital Library of Theses and Dissertations (28 October 2011) and also contacted relevant organisations (8 April 2011).

SELECTION CRITERIA

Randomised and quasi-randomised trials with randomisation at either individual or cluster level, evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy.

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. Data were checked for accuracy.

MAIN RESULTS

The search strategy identified 34 potentially eligible references. We included six trials assessing a total of 1023 women, excluded eight studies, and 10 studies are still ongoing. Five trials involving 623 women compared the effects of vitamin D alone versus no supplementation/placebo and one trial with 400 women compared the effects of vitamin D and calcium versus no supplementation.Only one trial with 400 women reported on pre-eclampsia: women who received 1200 IU vitamin D along with 375 mg of elemental calcium per day were as likely to develop pre-eclampsia as women who received no supplementation (average risk ratio (RR) 0.67; 95% confidence interval (CI) 0.33 to 1.35). Data from four trials involving 414 women consistently show that women who received vitamin D supplements had higher concentrations of vitamin D in serum at term than those women who received no intervention or a placebo; however the magnitude of the response was highly heterogenous. Data from three trials involving 463 women suggest that women who receive vitamin D supplements during pregnancy less frequently had a baby with a birthweight below 2500 grams than those women receiving no treatment or placebo; statistical significance was borderline (RR 0.48; 95% CI 0.23 to 1.01).In terms of other conditions, there were no significant differences in adverse side effects including nephritic syndrome (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women); stillbirths (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women) or neonatal deaths (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women) between women who received vitamin D supplements in comparison with women who received no treatment or placebo. No studies reported on preterm birth, maternal death, admission to neonatal intensive care unit/special nursery or Apgar scores.

AUTHORS' CONCLUSIONS

Vitamin D supplementation in a single or continued dose during pregnancy increases serum vitamin D concentrations as measured by 25-hydroxyvitamin D at term. The clinical significance of this finding and the potential use of this intervention as a part of routine antenatal care are yet to be determined as the number of high quality trials and outcomes reported is too limited to draw conclusions on its usefulness and safety. Further rigorous randomised trials are required to evaluate the role of vitamin D supplementation in pregnancy.

Vitamin D status and associations in newborn formula-fed infants during initial hospitalization

BACKGROUND

Evidence suggests that adequate vitamin D status in infancy plays a role in improving bone health and preventing disease, including type 1 diabetes, infections, and asthma. The objective of this study was to provide newborn hospitalized infants with American Academy of Pediatrics recommendations of 400 IU/day vitamin D-3 and measure the effect on serum 25(OH)D levels.

DESIGN

This trial was conducted August 2009 to June 2010. Infants were randomized to a control were measured from cord blood, every 7 days, and at discharge. Intact parathyroid hormone was measured at discharge.

PARTICIPANTS/SETTING

Fifty-two infants <32 weeks gestational age who received formula feedings during their neonatal intensive care unit hospitalization.

STATISTICAL ANALYSIS

Patient characteristics for each treatment group were summarized using descriptive statistics. The Mann-Whitney test was used to compare continuous variables, and categorical variables were compared using the χ(2) test or Fisher's exact test. The Pearson correlation coefficient was used to look at associations between continuous variables.

RESULTS

The mean cord blood level for all participants was 17.6±7.0 ng/mL. White infants had significantly higher 25(OH)D levels than non-white infants (P=0.0003). The mean 25(OH)D level at discharge of the supplemented group was 23.1±7.0 ng/mL (57.66±17.47 nmol/L), the mean 25(OH)D level of the unsupplemented group was 17.8±4.7 ng/mL (44.43±11.3 nmol/L), (P=0.007). Serum 25(OH)D showed a positive correlation with serum calcium in the first week of life (r=0.44, P=0.003) and negative correlation with parathyroid hormone levels at discharge (r=-0.35, P=0.02).

CONCLUSIONS

In newborn hospitalized infants, vitamin D-3 supplementation of 400 IU/day increased mean 25(OH)D levels from 17 ng/mL at birth to 23.1 ng/mL at discharge. Lower 25(OH)D levels were correlated with hypocalcemia during the first week of life, and elevated parathyroid hormone levels at discharge.

Effect of vitamin D supplementation during pregnancy on neonatal mineral homeostasis and anthropometry of the newborn and infant

Hypovitaminosis D is common in India. In the present prospective partially randomised study of vitamin D (D₃) supplementation during pregnancy, subjects were randomised in the second trimester to receive either one oral dose of 1500 μg vitamin D₃ (group 1, n 48) or two doses of 3000 μg vitamin D₃ each in the second and third trimesters (group 2, n 49). Maternal 25-hydroxyvitamin D (25(OH)D) at term, cord blood (CB) alkaline phosphatase (ALP), neonatal serum Ca and anthropometry were measured in these subjects and in forty-three non-supplemented mother-infant pairs (usual care). Median maternal 25(OH)D at term was higher in group 2 (58·7, interquartile range (IQR) 38·4-89·4 nmol/l) v. group 1 (26·2, IQR 17·7-57·7 nmol/l) and usual-care group (39·2, IQR 21·2-73·4 nmol/l) (P = 0·000). CB ALP was increased (>8.02 μkat/l or >480 IU/l) in 66·7 % of the usual-care group v. 41·9 % of group 1 and 38·9 % of group 2 (P = 0·03). Neonatal Ca and CB 25(OH)D did not differ significantly in the three groups. Birth weight, length and head circumference were greater and the anterior fontanelle was smaller in groups 1 and 2 (3·08 and 3·03 kg, 50·3 and 50·1 cm, 34·5 and 34·4 cm, 2·6 and 2·5 cm, respectively) v. usual care (2·77 kg, 49·4, 33·6, 3·3 cm; P = 0·000 for length, head circumference and fontanelle and P = 0·003 for weight). These differences were still evident at 9 months. We conclude that both 1500 μg and two doses of 3000 μg vitamin D₃ had a beneficial effect on infant anthropometry, the larger dose also improving CB ALP and maternal 25(OH)D.

Vitamin D supplementation during pregnancy: double-blind, randomized clinical trial of safety and effectiveness

The need, safety, and effectiveness of vitamin D supplementation during pregnancy remain controversial. In this randomized, controlled trial, women with a singleton pregnancy at 12 to 16 weeks' gestation received 400, 2000, or 4000 IU of vitamin D(3) per day until delivery. The primary outcome was maternal/neonatal circulating 25-hydroxyvitamin D [25(OH)D] concentration at delivery, with secondary outcomes of a 25(OH)D concentration of 80 nmol/L or greater achieved and the 25(OH)D concentration required to achieve maximal 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] production. Of the 494 women enrolled, 350 women continued until delivery: Mean 25(OH)D concentrations by group at delivery and 1 month before delivery were significantly different (p < 0.0001), and the percent who achieved sufficiency was significantly different by group, greatest in 4000-IU group (p < 0.0001). The relative risk (RR) for achieving a concentration of 80 nmol/L or greater within 1 month of delivery was significantly different between the 2000- and the 400-IU groups (RR = 1.52, 95% CI 1.24-1.86), the 4000- and the 400-IU groups (RR = 1.60, 95% CI 1.32-1.95) but not between the 4000- and. 2000-IU groups (RR = 1.06, 95% CI 0.93-1.19). Circulating 25(OH)D had a direct influence on circulating 1,25(OH)(2)D(3) concentrations throughout pregnancy (p < 0.0001), with maximal production of 1,25(OH)(2)D(3) in all strata in the 4000-IU group. There were no differences between groups on any safety measure. Not a single adverse event was attributed to vitamin D supplementation or circulating 25(OH)D levels. It is concluded that vitamin D supplementation of 4000 IU/d for pregnant women is safe and most effective in achieving sufficiency in all women and their neonates regardless of race, whereas the current estimated average requirement is comparatively ineffective at achieving adequate circulating 25(OH)D concentrations, especially in African Americans.

WITHDRAWN: Vitamin D supplementation in pregnancy

BACKGROUND

Vitamin D deficiency can occur in people whose diet is relatively low in the vitamin and those who are not exposed to much sunlight.

OBJECTIVES

The objective of this review was to assess the effects of vitamin D supplementation on pregnancy outcome.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (October 2001) and the Cochrane Controlled Trials Register (Issue 3, 2001).

SELECTION CRITERIA

Acceptably controlled trials of vitamin D supplementation during pregnancy.

DATA COLLECTION AND ANALYSIS

One reviewer assessed trial quality and extracted data.

MAIN RESULTS

Two trials involving 232 women were included. In one trial the mothers had higher mean daily weight gain and lower number of low birthweight infants. In the other trial the supplemented group had lower birthweights.

AUTHORS' CONCLUSIONS

There is not enough evidence to evaluate the effects of vitamin D supplementation during pregnancy.

Analyzing adherence to prenatal supplement: does pill count measure up?

Objective. To determine if adherence as measured by pill count would show a significant association with serum-based measures of adherence. Methods. Data were obtained from a prenatal vitamin D supplementation trial where subjects were stratified by race and randomized into three dosing groups: 400 (control), 2000, or 4000 IU vitamin D(3)/day. One measurement of adherence was obtained via pill counts remaining compared to a novel definition for adherence using serum 25-hydroxy-vitamin D (25-OH-D) levels (absolute change in 25(OH)D over the study period and the subject's steady-state variation in their 25(OH)D levels). A multivariate logistic regression model examined whether mean percent adherence by pill count was significantly associated with the adherence measure by serum metabolite levels. Results. Subjects' mean percentage of adherence by pill count was not a significant predictor of adherence by serum metabolite levels. This finding was robust across a series of sensitivity analyses. Conclusions. Based on our novel definition of adherence, pill count was not a reliable predictor of adherence to protocol, and calls into question how adherence is measured in clinical research. Our findings have implications regarding the determination of efficacy of medications under study and offer an alternative approach to measuring adherence of long half-life supplements/medications.

Profound Vitamin D Deficiency in a Diverse Group of Women during Pregnancy Living in a Sun-Rich Environment at Latitude 32°N

OBJECTIVE

Determine prevalence of vitamin D deficiency (VDD) in a diverse group of women presenting for obstetrical care at two community health centers in South Carolina at latitude 32°N.

METHODS AND DESIGN

Any pregnant woman presenting for care at 2 community health centers was eligible to participate. Sociodemographic and clinical history were recorded. A single blood sample was taken to measure circulating 25(OH)D as indicator of vitamin D status [25(OH)D < 20 ng/mL (50 nmol/L deficiency; <32 ng/mL (80 nmol/L) insufficiency]. Total serum calcium, phosphorus, creatinine, and intact parathyroid hormone also were measured.

RESULTS

559 women, [mean age 25.0 ± 5.4 (range 14-43) years] participated: African American (48%), Hispanic (38%), Caucasian/Other (14%). Mean gestational age was 18.5 ± 8.4 (median 14.6, range 6.4-39.6) weeks' gestation. 48% were VDD; an additional 37% insufficient. Greatest degree was in the African American women (68% deficient; 94% insufficient). In multivariable regression, 25(OH)D retained a significant negative association with PTH (P < .001).

CONCLUSIONS

VDD was high in a diverse group of women, greatest in those of darker pigmentation. The negative correlation between 25(OH)D and PTH confirms their corroborative use as biomarkers of VDD. These findings raise the issue of adequacy of current vitamin D recommendations for pregnant women.

Vitamin D intake during pregnancy: association with maternal characteristics and infant birth weight

BACKGROUND

Vitamin D insufficiency is beginning to be recognized as a public health problem. It is plausible that some portion of the lower Vitamin D levels which characterize minority populations is related to diet.

AIMS

We examined and described total Vitamin D intake during pregnancy from the mean of three 24-hour recalls plus use of dietary supplements.

STUDY DESIGN

Prospective cohort.

SUBJECTS

2251 low income, minority gravidae from Camden, New Jersey, USA.

OUTCOME MEASURES

Differences in total Vitamin D intake by maternal ethnicity. BMI and other factors (age, parity) and associations of total Vitamin D intake with gestation duration and birth weight adjusted for gestation.

RESULTS AND CONCLUSIONS

Total Vitamin D intake was significantly lower for minority gravidae (African American, and Hispanic, mainly Puerto Rican), for parous women, and for women with pregravid BMIs consistent with obesity or being overweight. After control for energy, other nutrients, and other potential confounding variables, total intake of Vitamin D was associated with increased infant birth weight; gravidae below the current adequate intake (<5 microg/day or 200 IU) had infants with significantly lower birth weights (p<0.05). Additional intake of Vitamin D may be of importance since higher intake is associated with increased birth weight in a population at risk of adverse pregnancy outcomes.

Prevention of rickets and vitamin D deficiency in infants, children, and adolescents

Rickets in infants attributable to inadequate vitamin D intake and decreased exposure to sunlight continues to be reported in the United States. There are also concerns for vitamin D deficiency in older children and adolescents. Because there are limited natural dietary sources of vitamin D and adequate sunshine exposure for the cutaneous synthesis of vitamin D is not easily determined for a given individual and may increase the risk of skin cancer, the recommendations to ensure adequate vitamin D status have been revised to include all infants, including those who are exclusively breastfed and older children and adolescents. It is now recommended that all infants and children, including adolescents, have a minimum daily intake of 400 IU of vitamin D beginning soon after birth. The current recommendation replaces the previous recommendation of a minimum daily intake of 200 IU/day of vitamin D supplementation beginning in the first 2 months after birth and continuing through adolescence. These revised guidelines for vitamin D intake for healthy infants, children, and adolescents are based on evidence from new clinical trials and the historical precedence of safely giving 400 IU of vitamin D per day in the pediatric and adolescent population. New evidence supports a potential role for vitamin D in maintaining innate immunity and preventing diseases such as diabetes and cancer. The new data may eventually refine what constitutes vitamin D sufficiency or deficiency.

Vitamin D: a growing perspective

Vitamin D deficiency has been widely reported in all age groups in recent years. Rickets has never been eradicated in developed countries, and it most commonly affects children from recent immigrant groups. There is much evidence that current vitamin D guidelines for the neonatal period, 5-10 microg (200-400 IU)/day, prevent rickets at the typical calcium intakes in developed countries. The annual incidence of vitamin D-deficiency rickets in developed countries ranges between 2.9 and 7.5 cases per 100,000 children. The prevalence of vitamin D deficiency in mothers and their neonates is remarkable, and the results of one study suggest that third-trimester 25-hydroxyvitamin D (25(OH)D) is associated with fetal bone mineral accrual that may affect prepubertal bone mass accumulation. Beyond infancy, the evidence indicates that 5 microg (200 IU)/day of vitamin D has little effect on vitamin D status as measured by the serum 25(OH)D concentration. Two randomized clinical trials show that higher vitamin D intake improves one-year gain in bone density in adolescent girls. The functions of vitamin D extend beyond bone to include immune system regulation and anti-proliferative effects on cells. Early life vitamin D inadequacy is implicated in the risk of bone disease, autoimmune disease, and certain cancers later in life; however, long-term interventional studies do not exist to validate the widespread implementation of greater vitamin D consumption. Here we review the available data concerning vitamin D status and health effects of vitamin D in pregnancy through to and including adolescence.

Vitamin D in pregnancy and lactation: maternal, fetal, and neonatal outcomes from human and animal studies

During pregnancy and lactation, mothers require significant amounts of calcium to pass on to the developing fetus and suckling neonate, respectively. Given the dependence of adult calcium concentrations and bone metabolism on vitamin D, one might anticipate that vitamin D sufficiency would be even more critical during pregnancy and lactation. However, maternal adaptations during pregnancy and lactation and fetal adaptations provide the necessary calcium relatively independently of vitamin D status. It is the vitamin D-deficient or insufficient neonate who is at risk of problems, including hypocalcemia and rickets. Due to poor penetrance of vitamin D and 25-hydroxyvitamin D [25(OH)D] into milk, exclusively breastfed infants are at higher risk of vitamin D deficiency than are formula-fed infants. Dosing recommendations for women during pregnancy and lactation might be best directed toward ensuring that the neonate is vitamin D-sufficient and that this sufficiency is maintained during infancy and beyond. A dose of vitamin D that provides 25(OH)D sufficiency in the mother during pregnancy should provide normal cord blood concentrations of 25(OH)D. Research has shown that during lactation, supplements administered directly to the infant can easily achieve vitamin D sufficiency; the mother needs much higher doses (100 mug or 4000 IU per day) to achieve adult-normal 25(OH)D concentrations in her exclusively breastfed infant. In addition, the relation (if any) of vitamin D insufficiency in the fetus or neonate to long-term nonskeletal outcomes such as type 1 diabetes and other chronic diseases needs to be investigated.

25-Hydroxyvitamin D: functional outcomes in infants and young children

Vitamin D deficiency occurs in the United States in exclusively breastfed infants who have high levels of skin pigmentation, inadequate vitamin D supplementation, and insufficient sunlight exposure. I review serum 25-hydroxyvitamin D [25(OH)D] concentrations and functional outcomes of vitamin deficiency in young children and breastfed and nonbreastfed infants. These outcomes include the presence or absence of vitamin D deficiency rickets, bone mineral content, and serum parathyroid hormone concentration. Daily vitamin D supplements of 400 IU/L keep serum 25(OH)D concentrations higher than 50 nmol/L and prevent rickets in infants and young children. The available evidence is not sufficient to support the use of bone mineral content or parathyroid hormone concentrations in infants and young children as functional outcomes to define deficient or sufficient levels of 25(OH)D. I therefore propose a research agenda to establish the functional definitions of vitamin D sufficiency or deficiency in infants and young children.

Vitamin D deficiency in children and adolescents: epidemiology, impact and treatment

Vitamin D deficiency is highly prevalent among children and adolescents worldwide. The high rates of vitamin D deficiency during childhood are of major public health relevance, given the growing evidence that vitamin D deficiency may play a key role in the pathophysiology of many chronic diseases beyond rickets, including autoimmune conditions, cardiovascular diseases, and cancer. Identification, treatment, and prevention of vitamin D deficiency in childhood may therefore have profound health effects throughout the life span. In this review, we discuss the definitions, epidemiology, clinical implications, and treatment of vitamin D deficiency in children and adolescents.

Vitamin D requirement during pregnancy and lactation

The current recommended dietary requirement for vitamin D intake (200 IU/d) during pregnancy and lactation is based on little, if any, scientific evidence, and as a result is clinically irrelevant with respect to maintaining nutritional vitamin D status during these demanding human conditions. Current research has shown that the actual dietary requirement during pregnancy and lactation may actually be as high as 6000 IU/d. Current data on which these new recommendations could be based are presented.

Vitamin D status in mothers and their newborns in Iran

BACKGROUND

Adequate vitamin D concentrations during pregnancy are necessary to neonatal calcium homeostasis, bone maturation and mineralization. The aim of study is to evaluate serum vitamin D concentrations in mothers and their newborns and effect of vitamin D deficiency on pregnancy outcomes.

METHODS

552 pregnant women were recruited from Tehran University educating hospitals in the winter of 2002. Maternal and cord blood samples were taken at delivery. The serum was assayed for 25-hydroxyvitamin D3, calcium, phosphorus and parathyroid hormone.

RESULTS

The prevalence of vitamin D deficiency in maternal and cord blood samples were 66.8% and 93.3%, respectively (<35 nmol/l). There was significant correlation between maternal and cord blood serum concentrations of vitamin D. In mothers with vitamin D deficiency, cord blood vitamin D concentrations was lower than those from normal mothers (P = .001). Also, a significant direct correlation was seen between maternal vitamin D intake and weight gain during pregnancy.

CONCLUSION

Consideration to adequate calcium and vitamin D intake during pregnancy is essential. Furthermore, we think it is necessary to reconsider the recommendation for vitamin D supplementation for women during pregnancy.

Bone status during adolescence, pregnancy and lactation

PURPOSE OF REVIEW

At birth, the fetus will contain 30 g of calcium; during the third trimester the calcium accrual can be up to 340 mg/day. Therefore, extremely high demands for calcium provision are placed upon the mother. This review aims to describe the adaptive mechanisms of the female skeleton to pregnancy and lactation, which ensure optimal fetal skeletal mineralization without compromise to maternal bone strength.

RECENT FINDINGS

Descriptions of changes in bone status during pregnancy and lactation have been published. One of the only studies to measure pre-conception to post-weaning shows complete recovery of maternal spinal bone mineral density (BMD) and near recovery at the hip. Most studies describe trabecular bone loss, but there is evidence for endosteal resorption of the metacarpals. In a retrospective study of former teenage mothers those who breastfed had similar hip BMD to nulliparous age-matched women; those who did not breastfeed had lower hip BMD. Maternal response to low calcium intake differs from that of normal calcium intake.

SUMMARY

Pregnancy and lactation do not have an overall negative effect upon the maternal skeleton. Retrospective evidence suggests no harmful effect of teenage pregnancy if the teenager breastfed, but this requires further investigation. The effects of other situations, for example low vitamin D status or low calcium intake, require further research to inform future clinical practice.

Review of vitamin D deficiency during pregnancy: who is affected?

OBJECTIVES

Vitamin D deficiencies have been documented in several populations, including aboriginal Canadians from isolated northern communities. Such deficiencies can impact the health of both the mother and her infant. This review was performed to determine how widespread vitamin deficiency is during pregnancy.

STUDY DESIGN

Electronic literature search.

METHODS

A Medline search was conducted using the Mesh terms "pregnancy" and "vitamin D". Those studies meeting the inclusion criteria were reviewed.

RESULTS

35 of 76 studies reported deficient mean, or median, concentrations of 25(OH)D. Low concentrations were reported among different ethnic groups around the world. In addition, deficient concentrations were identified in 3 northern First Nations communities in Manitoba.

CONCLUSIONS

Such deficiencies are of concern, as the developing fetus acquires its 25(OH)D across the placenta and may influence infant health. Future research is required to resolve the discourse surrounding ambiguous threshold values for vitamin D deficiencies and insufficiencies and to identify effective strategies to improve the vitamin D status of expectant women. Vitamin D supplementation may be necessary for many women during pregnancy, especially those in northern regions where endogenous synthesis may be constrained.

Prenatal and infant predictors of bone health: the influence of vitamin D

Vitamin D is essential for the health of pregnant women and their infants. Vitamin D insufficiency and deficiency during pregnancy are reflected in lower maternal weight gain and biochemical evidence of disturbed skeletal homeostasis in the infant, with, in extreme situations, reduced bone mineralization, radiologically evident rickets, and fractures. Populations at risk for vitamin D deficiency are those for which, for environmental, cultural, or medical reasons, exposure to sunlight is poor and the dietary intake of vitamin D is low. The infants born in such populations have low vitamin D stores and may receive little additional vitamin D if they are breast-fed without supplements for long periods. In the short term, lack of vitamin D supplementation in infancy leads to biochemical disturbances, reduced bone mineralization, slower growth, and eventual alterations in bone shape and increased risk of fracture, the hallmarks of rickets. In the longer term, lack of vitamin D supplementation may result in reduced bone size and mass during childhood and an increased risk of type 1 diabetes mellitus. Clear recommendations are needed regarding the intake of vitamin D during pregnancy and infancy. Such recommendations should be based on functional outcomes, rather than biochemical measurements, so that the medical problems resulting from the lack of this essential nutrient can be overcome.

Perinatal metabolism of vitamin D

During pregnancy, maternal serum concentrations of 25-hydroxyvitamin D, the circulating form of vitamin D, correlate with dietary vitamin D intake. Maternal serum concentrations of 1,25-dihydroxyvitamin D, the hormonal circulating and active form of vitamin D, are elevated during pregnancy; 1,25-dihydroxyvitamin D is synthesized mainly by the decidual cells of the placenta and allows for increased calcium absorption. The fetus is entirely dependent on the mother for its supply of 25-hydroxyvitamin D, which is believed to cross the placenta. Hypocalcemia and increased parathyroid hormone secretion induce synthesis of 1,25-dihydroxyvitamin D after birth in both full-term and preterm neonates. Nevertheless, serum concentrations of 25-hydroxyvitamin D are a rate-limiting factor in the synthesis of 1,25-dihydroxyvitamin D. In vitamin D-replete infants, circulating 1,25-dihydroxyvitamin D concentrations are higher than those observed in older infants. In countries where dairy products are not routinely supplemented with vitamin D, maternal vitamin D supplementation during pregnancy is necessary. However, there is no indication for the use of pharmacologic doses of vitamin D or its metabolites in the perinatal period.

Vitamin D supplementation in pregnancy

BACKGROUND

Vitamin D deficiency can occur in people whose diet is relatively low in the vitamin and those who are not exposed to much sunlight.

OBJECTIVES

The objective of this review was to assess the effects of vitamin D supplementation on pregnancy outcome.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register (October 1998).

SELECTION CRITERIA

Acceptably controlled trials of vitamin D supplementation during pregnancy.

DATA COLLECTION AND ANALYSIS

One reviewer assessed trial quality and extracted data.

MAIN RESULTS

Two trials involving 232 women were included. In one trial the mothers had higher mean daily weight gain and lower number of low birthweight infants. In the other trial the supplemented group had lower birthweights.

REVIEWER'S CONCLUSIONS

There is not enough evidence to evaluate the effects of vitamin D supplementation during pregnancy.

Inadequate vitamin D status: does it contribute to the disorders comprising syndrome 'X'?

Environmental factors are important in the aetiology of glucose intolerance, type II diabetes and IHD. The lack of vitamin D, which is necessary for adequate insulin secretion, relates demographically to increased risk of myocardial infarction. These disorders are connected, degenerative vascular disease increasing with glucose intolerance and diabetes and, with its risk factors, comprising syndrome 'X'. Evidence is presented suggesting that vitamin D deficiency may be an avoidable risk factor for syndrome 'X', adding another preventative measure to current recommendations which are aimed at reducing the worldwide epidemic of these disorders. Experimentally, vitamin D deficiency progressively reduces insulin secretion; glucose intolerance follows and becomes irreversible. Relationships between vitamin D status, glucose tolerance and 30 min insulin secretion during oral glucose tolerance tests are reported in British Asians; insulin secretion, but not glycaemia, improving with short-term supplementation. Studies showing reduction in blood pressure and in risk of heart attack and diabetes with exercise (usually outdoor), rarely consider the role of vitamin D status. Glycaemia and insulin secretion in elderly European men, however, relate to vitamin D status, independent of season or physical activity. Prolonged supplementation can improve glycaemia. Hypertension improves with vitamin D treatment with or without initial deficiency. Vitamin D status and climate are reviewed as risk factors for myocardial infarction; the risk reducing with altitude despite increasing cold. Glycaemia and fibrinogenaemia improve with insulin secretion increases in summer. Variation in vitamin D requirements could arise from genetic differences in vitamin D processing since bone density can vary with vitamin D-receptor genotype. Vitamin D receptors are present in islet beta cells and we report insulin secretion in healthy Asians differing profoundly with the Apa I genotype, being independent of vitamin D status. Those at risk of vitamin D deficiency include the elderly, those living indoors or having a covered-up style of dress, especially dark-skinned immigrants, and pregnant women, and these are groups recognized as being at increased risk of diabetes.

Prematurity as a predictor of rickets in Shanghai infants

The association between prematurity and the prevalence of rickets was examined among 2,227 infants in Shanghai, China. The prevalence of rickets during subjects' first 18 months of life was 6.8% in boys and 4.6% in girls. Pre-term infants were more likely to have rickets than term (> or = 37 weeks gestation) infants, 9.4% versus 5.2%. Birth weight was inversely related to the prevalence of rickets, 15.8% in the < 2,500 g group, 7.1% in the 2,500-2,999 g group, 4.9% in the 3,000-3,499 g group, and 4.2% in the > or = 3,500 g group. After adjusting for covariates including sex, average family income and birth weight, the odds ratio for rickets in pre-term infants was 1.55 compared with term infants. The inverse relationship between birth weight and rickets remained significant after taking sex, family income and pre-term birth into account. In addition, infants of the lower income families were more likely to have rickets than those of higher income families.

Zinc and copper in Asian pregnancies--is there evidence for a nutritional deficiency?

In 92 Hindu Asians, 59% of them vegetarian, and 51 Europeans longitudinal measurements were made during pregnancy of the zinc and copper concentrations in plasma and hair together with urinary zinc excretion, as indices of their zinc and copper status. Maternal diets were assessed once at booking. Zinc intakes ranged from 3.1 to 16.9 mg/day, with average intakes least in vegetarian Hindus and most in Europeans. Average copper intakes ranged between 1.48 and 1.80 mg/day and were similar in the three patient groups. Both ethnic groups showed the pregnancy-associated fall in the plasma concentration of zinc and rise in that of copper but throughout the study Hindus had statistically significant lower levels of zinc and higher levels of copper than Europeans. Urinary zinc excretion was not only significantly lower throughout the study in Hindus than in Europeans but the increase in excretion which occurred after 20 weeks gestation was smaller. There were no ethnic differences in the zinc content of hair. Urinary zinc excretion correlated with both plasma zinc levels and dietary zinc. Mean birthweight in the Hindus was 2912 g and 34% of infants were below the 10th centile, using the Aberdeen standards, compared with 6% of the European babies (mean birthweight 3349 g). No association was found between crude or adjusted birthweight and any of the measures of zinc or copper status in either ethnic group. The Hindus had an apparently lower average zinc status than the Europeans, but there was no evidence that this had acted as a nutritional constraint and was the cause of their slower rate of intrauterine growth.