The Effect of Multi mineral-Vitamin D Supplementation on Pregnancy Outcomes in Pregnant Women at Risk for Pre-eclampsia

Vitamin D supplementation for women during pregnancy

BACKGROUND

Vitamin D supplementation during pregnancy may help improve maternal and neonatal health outcomes (such as fewer preterm birth and low birthweight babies) and reduce the risk of adverse pregnancy outcomes (such as severe postpartum haemorrhage).

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 certain maternal and neonatal outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Trials Register (which includes results of comprehensive searches of CENTRAL, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, and relevant conference proceedings) (3 December 2022). We also searched the reference lists of retrieved studies.

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 studies against the inclusion criteria, ii) assessed trustworthiness based on pre-defined criteria of scientific integrity, iii) extracted data from included studies, and iv) assessed the risk of bias of the included studies. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

The previous version of this review included 30 studies; in this update, we have removed 20 of these studies to 'awaiting classification' following assessments of trustworthiness, one study has been excluded, and one new study included. This current review has a total of 10 included studies, 117 excluded studies, 34 studies in awaiting assessment, and seven ongoing studies. We used the GRADE approach to assess the certainty of the evidence. This removal of the studies resulted in evidence that was downgraded to low-certainty or very low-certainty due to study design limitations, inconsistency between studies, and imprecision. Supplementation with vitamin D compared to no intervention or a placebo A total of eight studies involving 2313 pregnant women were included in this comparison. We assessed four studies as having a low risk of bias for most domains and four studies as having high risk or unclear risk of bias for most domains. The evidence is very uncertain about the effect of supplementation with vitamin D during pregnancy compared to placebo or no intervention on pre-eclampsia (risk ratio (RR) 0.53, 95% confidence interval (CI) 0.21 to 1.33; 1 study, 165 women), gestational diabetes (RR 0.53, 95% CI 0.03 to 8.28; 1 study, 165 women), preterm birth (< 37 weeks) (RR 0.76, 95% CI 0.25 to 2.33; 3 studies, 1368 women), nephritic syndrome (RR 0.17, 95% CI 0.01 to 4.06; 1 study, 135 women), or hypercalcaemia (1 study; no cases reported). Supplementation with vitamin D during pregnancy may reduce the risk of severe postpartum haemorrhage; however, only one study reported this outcome (RR 0.68, 95% CI 0.51 to 0.91; 1 study, 1134 women; low-certainty evidence) and may reduce the risk of low birthweight; however, the upper CI suggests that an increase in risk cannot be ruled out (RR 0.69, 95% CI 0.44 to 1.08; 3 studies, 371 infants; low-certainty evidence). Supplementation with vitamin D + calcium compared to no intervention or a placebo One study involving 84 pregnant women was included in this comparison. Overall, this study was at moderate to high risk of bias. Pre-eclampsia, gestational diabetes, and maternal adverse events were not reported. The evidence is very uncertain about the effect of supplementation with vitamin D and calcium on preterm birth (RR not estimable; very low-certainty evidence) or for low birthweight (RR 1.45, 95% CI 0.14 to 14.94; very low-certainty evidence) compared to women who received placebo or no intervention. Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D) One study involving 1298 pregnant women was included in this comparison. We assessed this study as having a low risk of bias in all domains. Pre-eclampsia was not reported. The evidence is very uncertain about the effect of supplementation with vitamin D, calcium, and other vitamins and minerals during pregnancy compared to no vitamin D on gestational diabetes (RR 0.42, 95% CI 0.10 to 1.73; very low-certainty evidence), maternal adverse events (hypercalcaemia no events and hypercalciuria RR 0.25, 95% CI 0.02 to 3.97; very low-certainty evidence), preterm birth (RR 1.04, 95% CI 0.68 to 1.59; low-certainty evidence), or low birthweight (RR 1.12, 95% CI 0.82 to 1.51; low-certainty evidence).

AUTHORS' CONCLUSIONS

This updated review using the trustworthy assessment tool removed 21 studies from the previous update and added one new study for a total of 10 included studies. In this setting, supplementation with vitamin D alone compared to no intervention or a placebo resulted in very uncertain evidence on pre-eclampsia, gestational diabetes, preterm birth, or nephritic syndrome. It may reduce the risk of severe postpartum haemorrhage; however, only one study reported this outcome. It may also reduce the risk of low birthweight; however, the upper CI suggests that an increase in risk cannot be ruled out. Supplementation with vitamin D and calcium versus placebo or no intervention resulted in very uncertain evidence on preterm birth and low birthweight. Pre-eclampsia, gestational diabetes, and maternal adverse events were not reported in the only study included in this comparison. Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D) resulted in very uncertain evidence on gestational diabetes and maternal adverse events (hypercalciuria) and uncertain evidence on preterm birth and low birthweight. Pre-eclampsia was not reported in the only study included in this comparison. All findings warrant further research. 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.

Vitamin D and preeclampsia: A systematic review and meta-analysis

Objectives

Preeclampsia is one of the most frequent pregnancy disorders, with a global incidence of 2%-8%. Serum 25-hydroxyvitamin D is an essential mineral for human health; some studies suggest link between 25-hydroxyvitamin D deficiency and preeclampsia, while others offer contradictory findings. Thus, the goal of this study is to evaluate the relationships between maternal 25- hydroxyvitamin D concentrations and the risk of preeclampsia. In addition to this, our study also evaluates the effects of 25- hydroxyvitamin D supplementation on the incidence of preeclampsia. Therefore, assessing 25- hydroxyvitamin D's potential as a possible intervention to lower the risk of preeclampsia.

Methods

The Medline database was queried from inception until July 2021 for randomized controlled trials and observational studies without any restrictions. The studies assessing the association between 25-hydroxyvitamin D deficiency and preeclampsia and the impact of 25-hydroxyvitamin D supplementation on the incidence of preeclampsia were incorporated. The results were reported using a random-effects meta-analysis and the Mantel-Haenszel odds ratio. A p-value of <0.05 was considered significant for the analysis.

Results

This analysis includes 34 papers, including 10 randomized controlled trials and 24 observational studies. According to our pooled analysis, 25-hydroxyvitamin D supplementation was significantly associated with a lower risk of preeclampsia in pregnant women (OR: 0.50; 95% CI: 0.40-0.63; p = 0.00001), while 25-hydroxyvitamin D deficiency was significantly associated with an increased risk of preeclampsia (OR: 4.30; 95 % CI: 2.57-7.18; p < 0.00001, OR: 1.71; 95 % Cl: 1.27-2.32; p = 0.0005, OR 1.61; 95 % Cl: 1.21-2.16; p = 0.001).

Conclusion

Results suggest that 25-hydroxyvitamin D has a significant relationship with preeclampsia as confirmed by the findings that low maternal 25-hydroxyvitamin D concentrations cause increased risk of preeclampsia while 25-hydroxyvitamin D supplementation reduces the incidence of preeclampsia. Our findings indicate that 25-hydroxyvitamin D supplementation can be used as a possible intervention strategy in preventing one of the most common causes of maternal mortality around the world, preeclampsia.

Calcium supplementation to prevent pre-eclampsia: protocol for an individual participant data meta-analysis, network meta-analysis and health economic evaluation

INTRODUCTION

Low dietary calcium intake is a risk factor for pre-eclampsia, a major contributor to maternal and perinatal mortality and morbidity worldwide. Calcium supplementation can prevent pre-eclampsia in women with low dietary calcium. However, the optimal dose and timing of calcium supplementation are not known. We plan to undertake an individual participant data (IPD) meta-analysis of randomised trials to determine the effects of various calcium supplementation regimens in preventing pre-eclampsia and its complications and rank these by effectiveness. We also aim to evaluate the cost-effectiveness of calcium supplementation to prevent pre-eclampsia.

METHODS AND ANALYSIS

We will identify randomised trials on calcium supplementation before and during pregnancy by searching major electronic databases including Embase, CINAHL, MEDLINE, CENTRAL, PubMed, Scopus, AMED, LILACS, POPLINE, AIM, IMSEAR, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform, without language restrictions, from inception to February 2022. Primary researchers of the identified trials will be invited to join the International Calcium in Pregnancy Collaborative Network and share their IPD. We will check each study's IPD for consistency with the original authors before standardising and harmonising the data. We will perform a series of one-stage and two-stage IPD random-effect meta-analyses to obtain the summary intervention effects on pre-eclampsia with 95% CIs and summary treatment-covariate interactions (maternal risk status, dietary intake, timing of intervention, daily dose of calcium prescribed and total intake of calcium). Heterogeneity will be summarised using tau2, I2 and 95% prediction intervals for effect in a new study. Sensitivity analysis to explore robustness of statistical and clinical assumptions will be carried out. Minor study effects (potential publication bias) will be investigated using funnel plots. A decision analytical model for use in low-income and middle-income countries will assess the cost-effectiveness of calcium supplementation to prevent pre-eclampsia.

ETHICS AND DISSEMINATION

No ethical approvals are required. We will store the data in a secure repository in an anonymised format. The results will be published in peer-reviewed journals.

PROSPERO REGISTRATION NUMBER

CRD42021231276.

Maternal Vitamin D Levels and Its Correlation With Low Birth Weight in Neonates: A Tertiary Care Hospital Experience in Saudi Arabia

Introduction

A meta-analysis showed that 63.6% of the Saudi population have vitamin D deficiency, including many pregnant women. Studies showed that maternal vitamin D deficiency during pregnancy is a risk factor for low birth weight (LBW) in neonates. Neonatal LBW is a risk factor for multiple neonatal complications including respiratory distress syndrome, necrotizing enterocolitis, chronic renal disorders, seizures, and sepsis. Our objective in this study is to determine a correlation between low maternal vitamin D level and neonatal LBW in Saudi Arabia.

Methods

Neonates (n = 119) were divided based on their gestational age (GA) into full-term neonates (≥37 weeks) and preterm neonates (< 37 weeks) and based on birth weight into normal birth weight neonates (full-term = 2,500-3,500 g or preterm > 10th percentile) and LBW neonates (full-term < 2,500 g or preterm < 10th percentile). Vitamin D deficiency is defined as 25- hydroxyvitamin D level less than 50 nmol/L.

Results

Correlating neonatal birth weight with maternal vitamin D level during pregnancy was statistically insignificant for both full-term neonates and preterm neonates. In contrast, comparing the mean maternal vitamin D levels in each neonatal group showed that the mean were higher in mothers of neonates with normal birth weight.

Conclusion

Because 87.4% of mothers had low vitamin D levels during their pregnancy, correlation between maternal vitamin D level and LBW in neonates could not be found. However, mean maternal vitamin D levels were higher in mothers with normal birth weight neonates. Therefore, further detailed studies are required to establish local guidelines about the treatment of vitamin D deficiency during pregnancy.

A comparison of the risk of cesarean section in gestational diabetes mellitus patients supplemented antenatally with vitamin D containing supplements versus placebo: A systematic review and meta-analysis of double-blinded randomized controlled trials

The aim of this study was to study the role of vitamin D containing supplements in the risk of cesarean section (CS), a common complication in gestational diabetes mellitus (GDM) patients. An additional objective was to assess the risk of developing pre-eclampsia, preterm delivery, macrosomia, and polyhydramnios in these participants. Various electronic databases were searched for double-blinded parallel-arm randomized controlled trials that reported the incidence of CS in adult, non-insulin treated GDM patients who received vitamin D and placebo in different treatment arms, respectively. Next, each eligible trial’s risk of bias was assessed, and the effects of the above interventions on the respective outcomes were compared meta-analytically across the trials. This review included five Iranian trials sourcing data from nearly 380 participants. The risk of bias in the trials was primarily low. In contrast to the placebo group, the risk of CS [risk ratio (RR): 0.61, p=0.002, 95% confidence interval (CI): 0.44,0.83; I²=0%, p-value of Cochrane’s Q: 0.373) and macrosomia (RR: 0.31, p=0.006, 95% CI: 0.13,0.72; I²=0%, p-value of Cochrane’s Q: 0.935] was less in the vitamin D supplemented group. The remaining outcomes did not differ between the intervention groups. The antenatal use of vitamin D containing supplements in non-insulin treated GDM patients might reduce the risk of CS and macrosomia.

Effect of Vitamin D supplementation during pregnancy on maternal and perinatal outcomes

Vitamin D deficiency is common globally with a higher prevalence in women, especially during pregnancy. Among the pregnant women, Vitamin D deficiency was reported up to 80% in the Asian group. Vitamin D deficiency was related to a higher risk of maternal complications including preeclampsia, impaired glucose tolerance, and cesarean section rate, and neonatal complications including low birthweight, neonatal hypocalcemia seizure, and impaired skeletal, lung and immune development. There were no data supporting Vitamin D deficiency screening routinely in pregnancy regarding cost-effectiveness or health benefits. The measurement of Vitamin D in the high-risk group of women is necessary. Subsequent supplement with Vitamin D with and without calcium supplement during pregnancy had been statistically significantly reported to decrease the risk of preeclampsia, preterm birth, and low birth body weight. However, due to a lack of studies, the strategies of dietary and nutritional supplement for fetal growth restriction prevention are not statistically effective and are not yet recommended. The present review is to provide an overview of the clinical and the experimental evidence of Vitamin D deficiency-related complication and review of available options for the prevention and management of these complications.

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.

Multiple-micronutrient supplementation for women during pregnancy

BACKGROUND

Multiple-micronutrient (MMN) deficiencies often coexist among women of reproductive age in low- and middle-income countries. They are exacerbated in pregnancy due to the increased demands of the developing fetus, leading to potentially adverse effects on the mother and baby. A consensus is yet to be reached regarding the replacement of iron and folic acid supplementation with MMNs. Since the last update of this Cochrane Review in 2017, evidence from several trials has become available. The findings of this review will be critical to inform policy on micronutrient supplementation in pregnancy.

OBJECTIVES

To evaluate the benefits of oral multiple-micronutrient supplementation during pregnancy on maternal, fetal and infant health outcomes.

SEARCH METHODS

For this 2018 update, on 23 February 2018 we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP), and reference lists of retrieved studies. We also contacted experts in the field for additional and ongoing trials.

SELECTION CRITERIA

All prospective randomised controlled trials evaluating MMN supplementation with iron and folic acid during pregnancy and its effects on pregnancy outcomes were eligible, irrespective of language or the publication status of the trials. We included cluster-randomised trials, but excluded quasi-randomised trials. Trial reports that were published as abstracts were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

We identified 21 trials (involving 142,496 women) as eligible for inclusion in this review, but only 20 trials (involving 141,849 women) contributed data. Of these 20 trials, 19 were conducted in low- and middle-income countries and compared MMN supplements with iron and folic acid to iron, with or without folic acid. One trial conducted in the UK compared MMN supplementation with placebo. In total, eight trials were cluster-randomised.MMN with iron and folic acid versus iron, with or without folic acid (19 trials)MMN supplementation probably led to a slight reduction in preterm births (average risk ratio (RR) 0.95, 95% confidence interval (CI) 0.90 to 1.01; 18 trials, 91,425 participants; moderate-quality evidence), and babies considered small-for-gestational age (SGA) (average RR 0.92, 95% CI 0.88 to 0.97; 17 trials; 57,348 participants; moderate-quality evidence), though the CI for the pooled effect for preterm births just crossed the line of no effect. MMN reduced the number of newborn infants identified as low birthweight (LBW) (average RR 0.88, 95% CI 0.85 to 0.91; 18 trials, 68,801 participants; high-quality evidence). We did not observe any differences between groups for perinatal mortality (average RR 1.00, 95% CI 0.90 to 1.11; 15 trials, 63,922 participants; high-quality evidence). MMN supplementation led to slightly fewer stillbirths (average RR 0.95, 95% CI 0.86 to 1.04; 17 trials, 97,927 participants; high-quality evidence) but, again, the CI for the pooled effect just crossed the line of no effect. MMN supplementation did not have an important effect on neonatal mortality (average RR 1.00, 95% CI 0.89 to 1.12; 14 trials, 80,964 participants; high-quality evidence). We observed little or no difference between groups for the other maternal and pregnancy outcomes: maternal anaemia in the third trimester (average RR 1.04, 95% CI 0.94 to 1.15; 9 trials, 5912 participants), maternal mortality (average RR 1.06, 95% CI 0.72 to 1.54; 6 trials, 106,275 participants), miscarriage (average RR 0.99, 95% CI 0.94 to 1.04; 12 trials, 100,565 participants), delivery via a caesarean section (average RR 1.13, 95% CI 0.99 to 1.29; 5 trials, 12,836 participants), and congenital anomalies (average RR 1.34, 95% CI 0.25 to 7.12; 2 trials, 1958 participants). However, MMN supplementation probably led to a reduction in very preterm births (average RR 0.81, 95% CI 0.71 to 0.93; 4 trials, 37,701 participants). We were unable to assess a number of prespecified, clinically important outcomes due to insufficient or non-available data.When we assessed primary outcomes according to GRADE criteria, the quality of evidence for the review overall was moderate to high. We graded the following outcomes as high quality: LBW, perinatal mortality, stillbirth, and neonatal mortality. The outcomes of preterm birth and SGA we graded as moderate quality; both were downgraded for funnel plot asymmetry, indicating possible publication bias.We carried out sensitivity analyses excluding trials with high levels of sample attrition (> 20%). We found that results were consistent with the main analyses for all outcomes. We explored heterogeneity through subgroup analyses by maternal height, maternal body mass index (BMI), timing of supplementation, dose of iron, and MMN supplement formulation (UNIMMAP versus non-UNIMMAP). There was a greater reduction in preterm births for women with low BMI and among those who took non-UNIMMAP supplements. We also observed subgroup differences for maternal BMI and maternal height for SGA, indicating greater impact among women with greater BMI and height. Though we found that MMN supplementation made little or no difference to perinatal mortality, the analysis demonstrated substantial statistical heterogeneity. We explored this heterogeneity using subgroup analysis and found differences for timing of supplementation, whereby higher impact was observed with later initiation of supplementation. For all other subgroup analyses, the findings were inconclusive.MMN versus placebo (1 trial)A single trial in the UK found little or no important effect of MMN supplementation on preterm births, SGA, or LBW but did find a reduction in maternal anaemia in the third trimester (RR 0.66, 95% CI 0.51 to 0.85), when compared to placebo. This trial did not measure our other outcomes.

AUTHORS' CONCLUSIONS

Our findings suggest a positive impact of MMN supplementation with iron and folic acid on several birth outcomes. MMN supplementation in pregnancy led to a reduction in babies considered LBW, and probably led to a reduction in babies considered SGA. In addition, MMN probably reduced preterm births. No important benefits or harms of MMN supplementation were found for mortality outcomes (stillbirths, perinatal and neonatal mortality). These findings may provide some basis to guide the replacement of iron and folic acid supplements with MMN supplements for pregnant women residing in low- and middle-income countries.

Global inequities in dietary calcium intake during pregnancy: a systematic review and meta-analysis

BACKGROUND

Evidence shows that adequate calcium intake during pregnancy reduces the risk of hypertensive disorders of pregnancy. In most low- and middle-income countries (LMICs) the daily calcium intake is well below recommendations. Mapping calcium intake during pregnancy worldwide and identifying populations with low calcium intake will provide the evidence base for more targeted actions to improve calcium intake.

OBJECTIVE

To assess dietary calcium intake during pregnancy worldwide.

SEARCH STRATEGY

MEDLINE and EMBASE (from July 2004 to November 2017).

SELECTION CRITERIA

Cross-sectional, cohort, and intervention studies reporting calcium intake during pregnancy.

DATA COLLECTION AND ANALYSIS

Five reviewers working in pairs independently performed screening, extraction, and quality assessment. We reported summary measures of calcium intake and calculated the weighted arithmetic mean for high-income countries (HICs) and LMICs independently, and for geographic regions, among studies reporting country of recruitment, mean intake, and total number of participants. When available, inadequate intakes were reported.

MAIN RESULTS

From 1880 citations 105 works met the inclusion criteria, providing data for 73 958 women in 37 countries. The mean calcium intake was 948.3 mg/day (95% CI 872.1-1024.4 mg/day) for HICs and 647.6 mg/day (95% CI 568.7-726.5 mg/day) for LMICs. Calcium intakes below 800 mg/day were reported in five (29%) countries from HICs and in 14 (82%) countries from LMICs.

CONCLUSION

These results are consistent with a lack of improvement in calcium dietary intake during pregnancy and confirm the gap between HICs and LMICs, with alarmingly low intakes recorded for pregnant women in LMICs. From the public health perspective, in the absence of specific local data, calcium supplementation of pregnant women in these countries should be universal.

TWEETABLE ABSTRACT

Despite dietary recommendations, women in LMICs face pregnancy with diets low in calcium.

Vitamins supplementation affects the onset of preeclampsia

Preeclampsia may affect between 2-8% of all pregnancies. It seriously affects maternal health after pregnancy. This meta-analysis was performed to define the efficacy of vitamins supplementation on the risk of preeclampsia. Potential articles were systematically searched on the databases of Pubmed, Embase and Web of Science up to May 2016. Relative risk (RR) and 95% confidence intervals (95%CIs) were used to analyze the relationship of vitamins supplementation with risk of preeclampsia. Cochran Q test was used to test inter-study heterogeneity. Begg's funnel plot was adopted to assess the potential publication bias. 28 eligible studies were selected. Pooled results indicated that vitamins supplementation could reduce the risk of preeclampsia (RR = 0.74, 95%CI = 0.64-0.86). The studies with non-randomized controlled trial (RCT) analysis also suggested the significant relationship of vitamins supplementation with risk of preeclampsia (RR = 0.60, 95%CI = 0.42-0.85). However, negative results were observed in studies with RCT analysis. Subgroup analysis by vitamin type was performed among the studies with RCT analysis. The results indicated that vitamin D supplementation could significantly reduce the risk of preeclampsia (RR = 0.41, 95%CI = 0.22-0.78). Similar results were observed in the studies with multivitamins supplementation (RR = 0.69, 95%CI = 0.51-0.93). Vitamins supplementation could reduce the onset of preeclampsia.

Vitamin D and its impact on maternal-fetal outcomes in pregnancy: A critical review

The role of vitamin D beyond its classical function in calcium homeostasis has been of significant interest in recent years. There has been expanding research on the pleiotropic role of vitamin D in pregnancy and the implications of its deficiency on maternal-fetal outcomes. Several studies have associated low maternal vitamin D status to adverse outcomes in pregnancy, including preeclampsia, gestational diabetes, preterm births, low birth weight, and others. Several randomized controlled clinical trials of Vitamin D supplementation during pregnancy have also been conducted. Though some of the studies found improvement in pregnancy outcomes with vitamin D supplementation, others have not shown any association. In this article, we have critically reviewed the observational and interventional studies, published primarily within the past two years (January 2014 to February 2016) on the influence of vitamin D deficiency on pregnancy and the impact of its supplementation. The potential underlying mechanisms of vitamin D in regulating each of the outcomes have also been discussed.

Early pregnancy vitamin D status and risk of preeclampsia

BACKGROUND

Low vitamin D status in pregnancy was proposed as a risk factor of preeclampsia.

METHODS

We assessed the effect of vitamin D supplementation (4,400 vs. 400 IU/day), initiated early in pregnancy (10-18 weeks), on the development of preeclampsia. The effects of serum vitamin D (25-hydroxyvitamin D [25OHD]) levels on preeclampsia incidence at trial entry and in the third trimester (32-38 weeks) were studied. We also conducted a nested case-control study of 157 women to investigate peripheral blood vitamin D-associated gene expression profiles at 10 to 18 weeks in 47 participants who developed preeclampsia.

RESULTS

Of 881 women randomized, outcome data were available for 816, with 67 (8.2%) developing preeclampsia. There was no significant difference between treatment (N = 408) or control (N = 408) groups in the incidence of preeclampsia (8.08% vs. 8.33%, respectively; relative risk: 0.97; 95% CI, 0.61-1.53). However, in a cohort analysis and after adjustment for confounders, a significant effect of sufficient vitamin D status (25OHD ≥30 ng/ml) was observed in both early and late pregnancy compared with insufficient levels (25OHD <30 ng/ml) (adjusted odds ratio, 0.28; 95% CI, 0.10-0.96). Differential expression of 348 vitamin D-associated genes (158 upregulated) was found in peripheral blood of women who developed preeclampsia (FDR <0.05 in the Vitamin D Antenatal Asthma Reduction Trial [VDAART]; P < 0.05 in a replication cohort). Functional enrichment and network analyses of this vitamin D-associated gene set suggests several highly functional modules related to systematic inflammatory and immune responses, including some nodes with a high degree of connectivity.

CONCLUSIONS

Vitamin D supplementation initiated in weeks 10-18 of pregnancy did not reduce preeclampsia incidence in the intention-to-treat paradigm. However, vitamin D levels of 30 ng/ml or higher at trial entry and in late pregnancy were associated with a lower risk of preeclampsia. Differentially expressed vitamin D-associated transcriptomes implicated the emergence of an early pregnancy, distinctive immune response in women who went on to develop preeclampsia.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00920621.

FUNDING

Quebec Breast Cancer Foundation and Genome Canada Innovation Network. This trial was funded by the National Heart, Lung, and Blood Institute. For details see Acknowledgments.