Correlation between vitamin D3 deficiency and insulin resistance in pregnancy

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.

Association of VDR gene variant rs2228570-FokI with gestational diabetes mellitus susceptibility in Arab women

Gestational diabetes mellitus (GDM) has been linked with adverse pregnancy outcomes. Vitamin D receptor (VDR) gene variants have been associated with diabetes mellitus susceptibility and related complications. This study assessed the association between VDR gene polymorphism (rs2228570) and GDM risk among pregnant Arab women. A total of 368 pregnant Saudi women who were screened for GDM at 24-28 weeks of gestation and genotyped for the VDR gene variant (rs2228570) were included in this cross-sectional study. Circulatory insulin levels, fasting blood glucose (FBG), glycated hemoglobin (HbA1c), and vitamin D (25(OH)D) were measured. There were 108 women with GDM and 260 women without GDM. The genotype frequency of women with GDM was CC 60.2 %, CT 33.3 %, TT 6.9 %, and CT + TT 39.8 %; for non-GDM women, were CC 61.1 %, CT 31.5 %, TT 6.9 %, and CT + TT 38.4 %. No association was found between the VDR gene variant (rs2228570-FokI) and GDM susceptibility after adjustment for covariates. Serum 25(OH)D had a significant inverse association with FBG (r = -0.49, p = 0.01) and HbA1c (r = -0.45, p = 0.03) among carriers of the TT-genotype. Furthermore, a significant inverse correlation was observed between serum 25(OH)D and HOMA-β (r = -0.20, p = 0.035) in individuals with the T-allele. Among pregnant Saudi women, glycemic indices appear to be influenced by vitamin D, suggesting a possible role it may play in mitigating the metabolic changes associated with GDM, particularly among individuals with specific genetic backgrounds. In our study population, rs2228570-FokI did not appear to be a significant contributor to GDM risk.

Prevalence of vitamin D insufficiency in early pregnancies- a Singapore study

Vitamin D plays an essential role in bone and mineral metabolism. There is increased interest in understanding prevalence of Vitamin D deficiency in pregnancy as many studies report association of low vitamin D levels with obstetric complications and neonatal sequelae. There is a paucity of studies in Singapore evaluating levels of vitamin D levels during the first trimester of pregnancies. We aim to study the prevalence of vitamin D insufficiency in this population. Our study assessed vitamin D levels in these women. Vitamin D (Plasma 25(OH)D concentration) levels in multiracial women during the first trimester were collected via venepuncture at their booking antenatal visit. They were stratified into sufficient ≥30ng/ml, insufficient ≥20ng/ml and <30ng/ml, moderately deficient ≥10ng/ml and <20ng/ml and severely deficient <10ng/ml. 93 women were included in this study. Only 2.2% of our study population had sufficient vitamin D levels. In women who had insufficient levels, the heavier the weight, the more likely to be vitamin D deficient. Interestingly, we also note that the older the patient, the less likely they are to be deficient. In women with periconceptual multivitamin supplementation, the average vitamin D level for those with supplementation was 2.10ng/ml higher than those without. Majority of patients were recruited from a single study member's patient pool who were mostly Chinese. Prevalence of Vitamin D deficiency in general obstetric patients with higher BMI and darker skinned patients may be even lower in Singapore. The high prevalence of Vitamin D insufficiency in our patients prove that it is a prominent problem in our population. We aim to implement screening of vitamin D levels as part of antenatal investigations in the first trimester and recommend supplementation as required. We also hope to evaluate the association of low vitamin D levels with obstetric or neonatal complications further understanding its implications.

High-Dose Vitamin D Supplementation Significantly Affects the Placental Transcriptome

Vitamin D deficiency is a highly prevalent obstetrical concern associated with an increased risk of complications like pre-eclampsia, gestational diabetes, and growth retardation. Vitamin D status in pregnancy is also linked to long-term offspring health, e.g., the risk of obesity, metabolic disease, and neurodevelopmental problems. Despite the suspected role of vitamin D in placental diseases and fetal development, there is limited knowledge on the effect of vitamin D on placental function. Thus, we performed next-generation RNA sequencing, comparing the placental transcriptome from uncomplicated term pregnancies receiving the often-recommended dose of 10 µg vitamin D/day (n = 36) with pregnancies receiving 90 µg/day (n = 34) from late first trimester to delivery. Maternal vitamin D status in the first trimester was also considered. We found that signaling pathways related to cell adhesion, immune function, and neurodevelopment were affected, supporting that increased vitamin D supplementation benefits placental function in established pregnancies without severe vitamin D deficiency, also underlining the importance of vitamin D in brain development. Specific effects of the first trimester vitamin D status and offspring sex were also identified. Further studies are warranted, addressing the optimal vitamin status during pregnancy with a focus on organ-specific vitamin D needs in individual pregnancies.

Analysis of single nucleotide polymorphisms associated with the vitamin D pathway in the placentas of women with gestational diabetes mellitus: a laboratory study

BACKGROUND

The aim of this study was to analyze the single nucleotide polymorphisms (SNPs) of genes known to be involved in vitamin D metabolism in the placenta using the placental tissue of mothers diagnosed with gestational diabetes mellitus (GDM) to determine whether the SNPs and occurrence of GDM are related.

METHODS

We enrolled 80 women of the same gestational age, 40 with and 40 without GDM. The placenta was obtained from each woman after delivery and SNP genotyping was performed on seven SNPs in the CYP27B1 (rs10877012), CYP24A1 (rs2248359, rs6013897, and rs2209314), and GC (rs2282679, rs16847024, and rs3733359) genes. Maternal serum 25-hydroxyvitamin D levels were measured during the first trimester of pregnancy and before delivery.

RESULTS

At the time of delivery, vitamin D levels were lower (21.05±12.05 mg/dL vs. 31.31±20.72 mg/dL, p=0.012) and the frequency of vitamin D deficiency was higher (60.7% vs. 32.5%, p=0.040) in the GDM group. In women with GDM, the G allele of rs10877012 was more common (86.3% vs. 65.0%, p=0.002). The rs10877012 GG genotype was more common in the GDM group (72.5% vs. 42.5%, p=0.007) and the rs10877012 TT genotype was more common in the control group (12.5% vs. 0%, p=0.007).

CONCLUSION

Mothers with GDM have lower serum concentrations of vitamin D before delivery than healthy controls and vitamin D deficiency is common. A polymorphism in CYP27B1 (rs10877012), is considered to be a cause of GDM pathogenesis.

The Impact of Vitamin D Deficiency on Infants' Health

Vitamin D is an essential nutrient that plays a vital role in bone health and musculoskeletal development. The aim of this narrative review is to present up-to-date information about the impact of vitamin D deficiency (VDD) on the health status of infants in their first year of life. Vitamin D is indispensable for skeletal growth and bone health, and emerging research suggests that it may also have significant roles in maternal and fetal health. VDD affects a large proportion of infants according to current guidelines. However, its prevalence varies depending on geographic location, skin pigmentation, and the time of year. Based on current guidelines for normal vitamin D levels and recommended daily intake, studies suggest that VDD is a global health issue with potentially significant implications for those at risk, especially infants. Our understanding of the role of vitamin D has improved significantly in the last few decades. Systematic reviews and meta-analyses investigating the effect of vitamin D on preterm birth, low birth weight, anthropometric parameters, and health outcomes such as infectious diseases in infants, have found conflicting or inconsistent results. It is important to encourage further research to fill in these knowledge gaps and develop national or global strategies that ease the burden of VDD, especially in groups at risk.

Vitamin D: Can Gender Medicine Have a Role?

This narrative review aims to shed light on the role of gender differences, on the biological and molecular functions in the main pathological mechanisms that recognize the role of vitamin D. Vitamin D deficiency is widespread worldwide, but it is still very controversial whether the amount of vitamin D taken daily is actually the only problem related to its biological functions. Currently, the plasma concentration of 25-hydroxyvitamin D represents the only indicator of the circulating blood quota. The concept is that the biological function of vitamin D is not only linked to its circulating levels, but it is hypothesized that its biological functions depend, above all, on its total bioavailability. In particular, vitamin D circulates for the most part linked to albumin and vitamin D binding protein (DBP), which depend on various pathological conditions and physiologically, above all, the function of the latter is regulated by estrogens, glucocorticoids, and inflammatory cytokines. During her life, women undergo various changes in the hormonal and sexual sphere concerning menarche, possible pregnancies, and breastfeeding but also the use of contraceptives and, finally, the transition from the period of fertility to menopause. Each of these phases presents specific needs and, consequently, sometimes also specific criticalities. Studies on young women have shown that vitamin D deficiency is present in 58 to 91% of cases. Obesity, metabolic disorders, and variation in estrogen contraction may affect vitamin D deficiency due to the decreased bioavailability from dietary sources due to deposition in body fat compartments.

Abnormal glucose tolerance in women with prior gestational diabetes mellitus: a 4-year follow-up study

BACKGROUND

Adoption of the International Association of Diabetes and Pregnancy Study Group (IADPSG) criteria for diagnosis of gestational diabetes mellitus (GDM) varies worldwide. Early detection of women at increased risk of developing type 2 diabetes mellitus (T2DM) following GDM enables initiation of measures to delay disease onset.

OBJECTIVES

To determine the 4-year cumulative incidence and risk factors for developing abnormal glucose tolerance (AGT) among women with previous GDM using modified IADPSG criteria. Additionally, to review post-natal attendance at diabetes screening and the impact of post-partum lifestyle modifications and breastfeeding on the risk of T2DM development.

METHODS

Four hundred twenty-six women with a prior history of GDM were invited to participate in the study, 4 years after the index pregnancy. The following were completed: body measurements, oral glucose tolerance test (OGTT), glycated haemoglobin (HbA1c), vitamin D, and other biochemistry measurements. Participants also completed a lifestyle questionnaire.

RESULTS

Of the 74 women who participated, 15 (20%) had AGT. Predictive factors for AGT development were as follows: fasting glucose levels (p = 0.004), HbA1c (p = 0.008) at GDM diagnosis, and early pregnancy BMI (p = 0.001). Thirty-three (45%) women had not attended their postnatal screening. The odds ratio of the association between breastfeeding and AGT development was 0.16 (95% CI: 0.05 to 0.53).

CONCLUSION

The proportion of women who develop AGT after a diagnosis of GDM remains high. The factors associated with progression to AGT are available at GDM diagnosis. Preventing AGT in this group is possible by supporting breastfeeding. Attendance at post-natal screening should also be encouraged.

Maternal plasma vitamin D levels across pregnancy are not associated with neonatal birthweight: findings from an Australian cohort study of low-risk pregnant women

BACKGROUND

In utero environments can be highly influential in contributing to the development of offspring obesity. Specifically, vitamin D deficiency during pregnancy is associated with adverse maternal and child health outcomes, however its relationship with offspring obesity remains unclear. We assessed maternal vitamin D status across pregnancy, change in plasma vitamin D concentrations and associations with neonatal birthweight, macrosomia and large for gestational age.

METHODS

Women (n = 221) aged 18-40 years with singleton (low-risk) pregnancies, attending antenatal clinics at a tertiary-level maternity hospital were recruited at 10-20 weeks gestation. Medical history, maternal weight and blood samples at three antenatal clinic visits were assessed; early (15 ± 3 weeks), mid (27 ± 2 weeks) and late (36 ± 1 weeks) gestation. Maternal 25(OH)D was analysed from stored plasma samples via liquid chromatography-tandem mass spectrometry (LC/MS/MS). Neonatal growth parameters were collected at birth. Unadjusted and adjusted linear and logistic regression assessed associations of maternal vitamin D with birthweight, macrosomia and large for gestational age.

RESULTS

Mean plasma 25(OH)D increased from early (83.8 ± 22.6 nmol/L) to mid (96.5 ± 28.9 nmol/L) and late (100.8 ± 30.8 nmol/L) gestation. Overall 98% of women were taking vitamin D-containing supplements throughout their pregnancy. Prevalence of vitamin D deficiency (25(OH)D < 50 nmol/L) was 6.5%, 6.3% and 6.8% at early, mid and late pregnancy respectively. No statistically significant association was found between 25(OH)D or vitamin D deficiency at any timepoint with neonatal birthweight, macrosomia or large for gestational age.

CONCLUSIONS

Prevalence of vitamin D deficiency was low in this cohort of pregnant women and likely related to the high proportion of women taking vitamin D supplements during pregnancy. Maternal 25(OH)D did not impact offspring birth weight or birth size. Future studies in high-risk pregnant populations are needed to further assess maternal vitamin D status and factors in utero which promote early life obesity.

Effect of supplementation with 5,000 IU of vitamin D on the glycemic profile of women with gestational diabetes mellitus

OBJECTIVES

The frequency of GDM and vitamin D insufficiency in Mexico is high. Vitamin D supplementation in GDM patients has shown favorable but non-homogeneous results regarding improvement of glycemic profile. The aim of the study was to assess the effects of supplementing with 5,000 IU of vitamin D on the glycemic profile of women with GDM.

METHODS

A randomized clinical trial was conducted on women with GDM who received 5,000 IU of vitamin D (n=27) or a placebo (n=27) for eight weeks. Changes in vitamin D levels and metabolic parameters before and after the intervention were analyzed.

RESULTS

Vitamin D vs. placebo: 25-OHD (32 vs. 26 ng/mL, p=0.006), HbA_1c (6.0 vs. 6.1%, p=0.29), glucose (99 vs. 87 mg/dL, p=0.29), insulin (14 vs. 13 µIU/mL, p=0.79), HOMA-IR (3.6 vs. 2.6, p=0.55), QUICKI (0.31 vs. 0.33, p=0.55).

CONCLUSIONS

Supplementation with 5,000 IU of vitamin D for eight weeks had no significant effect on the glycemic profile.

The Weak Relationship between Vitamin D Compounds and Glucose Homeostasis Measures in Pregnant Women with Obesity: An Exploratory Sub-Analysis of the DALI Study

Studies on the relationship between vitamin D (VitD) and glucose homeostasis usually consider either total VitD or 25OHD3 but not 25OHD2 and epimers. We aimed to evaluate the cross-sectional association of VitD compounds with glucose homeostasis measurements in pregnant women with overweight/obesity participating in the Vitamin D And Lifestyle Intervention for Gestational Diabetes Mellitus Prevention study. Methods: The analysis included 912 women. Inclusion criteria: <20 weeks gestation, body mass index ≥29 kg/m2 and information on exposure and outcome variables at baseline. Measurements: A 75 g OGTT at <20, 24−28 and 35−37 weeks gestation (except if previous diabetes diagnosis). Exposure variables: 25OHD2, 25OHD3 and C3-epimer. Outcome variables: fasting and post-challenge insulin sensitivity and secretion indices, corresponding disposition indices (DI), plasma glucose at fasting and 1 and 2 h, hyperglycemia in pregnancy (HiP). Statistics: Multivariate regression analyses with adjustment. Results: Baseline VitD sufficiency was 66.3%. Overall, VitD compounds did not show strong associations with any glucose homeostasis measures. 25OHD3 showed direct significant associations with: FPG at <20 and 24−28 weeks (standardized β coefficient (β) 0.124, p = 0.030 and 0.111, p = 0.026 respectively), 2 h plasma glucose at 24−28 weeks (β 0.120, p = 0.018), and insulin sensitivity (1/HOMA-IR, β 0.127, p = 0.027) at 35−37 weeks; it showed an inverse association with fasting DI (QUCKI*HOMA-β) at <20 and 24−28 weeks (β −0.124, p = 0.045 and β −0.148, p = 0.004 respectively). 25OHD2 showed direct associations with post-challenge insulin sensitivity (Matsuda, β 0.149, p = 0.048) at 24−28 weeks) and post-challenge DI (Matsuda*Stumvoll phase 1) at 24−28 and 35−37 weeks (β 0.168, p = 0.030, β 0.239, p = 0.006). No significant association with C3-epimer was observed at any time period. Conclusions: In these women with average baseline VitD in sufficiency range, VitD compounds did not show clear beneficial associations with glucose homeostasis measures.

Prevalence of vitamin D deficiency and its association with metabolic syndrome among the elderly population of Birjand, Iran

Background

With increasing life expectancy and the aging population of most countries, attention to the diseases of old age has also increased. Due to the high prevalence of vitamin D deficiency in the elderly, the present study was designed and performed to investigate the relationship between serum vitamin D levels in Iranian elderly with the risk of metabolic syndrome (MetS).

Methods

This study was conducted on an elderly population of Birjand (60 and older) in the urban and rural areas of the city. In 1325 elderly men and women, with age range of 60 and older, serum 25-hydroxyvitamin D, anthropometric measurements and laboratory variables were measured.

Results

Twenty-eight percent of the elderly participants in the study had vitamin D deficiency. We found that participants with higher 25(OH)D had lower odds for elevated waist circumference (WC) (OR = 0.91, 95% CI 0.83-0.98), reduced HDL (OR = 0.96, 95% CI 0.86-0.97) and elevated fasting blood sugar (FBS) (OR = 0.96, 95% CI 0.89-0.98). We not found any significant association between 25(OH)D levels and other MetS components.

Conclusion

Higher 25(OH)D levels in the elderly are linked to a reduced prevalence of MetS and, specifically, higher levels of favorable HDL-C, WC and FBS. Further intervention studies are needed to substantiate the results of this study.

The role of nutrition in the development and management of gestational diabetes among Iranian women: a systematic review and meta-analysis

Purpose

We aimed to review existing evidence on nutrition associations with gestational diabetes mellitus (GDM) development and management among Iranian women.

Methods

Web of Science, PubMed, Scopus, SID, and Magiran were searched up to August 2020. Observational studies on associations between circulatory markers of vitamins and minerals, dietary intakes, and GDM and clinical trials of the effects of nutritional supplementations or dietary modifications on management or prevention of GDM among Iranian women were selected.

Results

We reviewed 49 publications. Pooled analyses revealed that GDM women had lower serum vitamin D (-8.31 nmol/l (95% CIs= -14.4, -2.19), higher serum iron (26.2 μg/dl (95% CIs= 2.52, 49.8), ferritin (24.1 ng/ml (95% CIs= 15.0, 33.4), and haemoglobin (1.14 g/dl (95% CIs: 0.32, 1.96) levels than non-GDM women. Single studies found the inverse associations of the Mediterranean diet, dietary approaches to stop hypertension diet, plant-based dietary index, and the direct associations of dietary acid load and dietary inflammatory index with the odds of GDM. Vitamin D supplementation early in pregnancy prevented GDM in two clinical trials. In two studies, iron supplementation's effect on GDM in non-anemic women was inconsistent. Pooled analyses of probiotic supplementation in women with GDM showed no significant impact on maternal glycemia.

Conclusions

Vitamin D supplementation early in pregnancy may reduce the incidence of GDM. There is no compelling evidence that vitamin D or probiotics can help with GDM management. There is currently inadequate data to recommend a specific dietary pattern to prevent GDM in Iranian women.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-021-00944-7.

PM2.5 exposure and maternal glucose metabolism in early pregnancy: Associations and potential mediation of 25-hydroxyvitamin D

Gestational diabetes mellitus (GDM) has become a new global epidemic with a rapidly increasing prevalence. Previous studies have suggested that air pollution is associated with GDM risk, but the results are inconsistent, and mechanistic studies are limited. Based on a hospital-based cohort, a total of 6374 participants were included in this study. Individual daily PM2.5 exposure at a 1-km resolution was predicted using a full-spatiotemporal-coverage model. The results of multiple linear regression showed that glycated hemoglobin (HbA1c) was significantly associated with PM2.5 both in the 1-month preconception and in the first trimester of pregnancy. Additionally, HbA1c decreased 0.437% (95% CI: -0.629, -0.244) as the serum 25-hydroxyvitamin D (25(OH)D) increased by one interquartile range (IQR) (9.2 ng/ml). An IQR increase in PM2.5 exposure was also negatively associated with serum 25(OH)D (estimated change% and 95% CI: -7.249 (-9.054, -5.408) in the 1-month preconception and - 13.069 (-15.111, -10.979) in the first trimester of pregnancy). Mediation analysis showed that serum 25(OH)D status mediated the association between HbA1c and PM2.5 exposure both in the preconception and in the first trimester (mediated percent: 2.00% and 4.05% (Sobel p＜0.001), respectively). The result suggested a vicious cycle among PM2.5 exposure, lower serum VD status and a higher HbA1c. More studies are warranted since the protective effect of 25(OH)D against glucose disorders associated with air pollution in this study was limited.

PTH-rP and PTH-R1 Expression in Placentas from Pregnancies Complicated by Gestational Diabetes: New Insights into the Pathophysiology of Hyperglycemia in Pregnancy

Background: this study investigated the expression of parathyroid hormone-related protein (PTH-rP) and PTH/PTH-rP receptor PTH-R1 in placentas from women with gestational DM (GDM), and the relationship between PTH-R1 and PTH-rP expression and pregnancy characteristics. Methods: we prospectively enrolled 78 pregnant women with GDM, and immunochemistry for PTH-rP and PTH-R1 was performed on placentas. Patients were grouped according to the positivity of PTH-R1 or PTH-rP expression, and pregnancy characteristics were compared between the two groups. Results: PTH-rP and PTH-R1 expression were highest in the extravillous cytotrophoblast and in the decidua. In extravillous cytotrophoblast, PTH-rP expression was higher in women with abnormal at fasting glycemia compared to women with abnormal 60′ or 120′ glycemia (25/25, 50% vs. 6/28, 21.4%, χ2 = 6.12, p = 0.01), and PTH-R1 expression was higher in women with abnormal oral glucose tolerance test (OGTT) at fasting glycemia compared to women with abnormal 60′ or 120′ glycemia (37/50, 74% vs. 15/28, 53.6%, χ2 = 3.37, p = 0.06). In syncytiotrophoblast, PTH-rP-positive placentas were characterized by higher incidence of 1 min Apgar score < 7 (2/9, 22.2% vs. 2/69, 2.9%, χ2 = 6.11, p = 0.01) and maternal obesity (4/9, 44.4% vs. 11/69, 16.7%, χ2 = 3.81, p = 0.05). Conclusion: placental PTH-rP and PTH-R1 expression is dependent on the type of maternal hyperglycemia, and it is associated with adverse pregnancy outcomes.

Immunoendocrine Dysregulation during Gestational Diabetes Mellitus: The Central Role of the Placenta

Gestational Diabetes Mellitus (GDM) is a transitory metabolic condition caused by dysregulation triggered by intolerance to carbohydrates, dysfunction of beta-pancreatic and endothelial cells, and insulin resistance during pregnancy. However, this disease includes not only changes related to metabolic distress but also placental immunoendocrine adaptations, resulting in harmful effects to the mother and fetus. In this review, we focus on the placenta as an immuno-endocrine organ that can recognize and respond to the hyperglycemic environment. It synthesizes diverse chemicals that play a role in inflammation, innate defense, endocrine response, oxidative stress, and angiogenesis, all associated with different perinatal outcomes.

Prevalence and association with birth outcomes of low vitamin D levels among pregnant women living with HIV

OBJECTIVES

To evaluate the prevalence of low vitamin D levels among well treated pregnant women living with HIV (WLWH) on combination antiretroviral therapy in Denmark, to identify risk factors of low vitamin D levels, and to assess the association between vitamin D status and birth outcomes.

DESIGN

Nationwide cohort study.

METHODS

All WLWH in Denmark giving birth from 2000 to 2018 with a vitamin D measurement during pregnancy were identified. Risk factors for low vitamin D (deficiency or insufficiency) were assessed using log-binomial regression models, both univariate and adjusted for maternal and HIV factors. The association between vitamin D status and birth outcomes was assessed using linear regression models for continuous outcomes and log-binomial models for binary outcomes.

RESULTS

Among 208 WLWH, the prevalence of vitamin D deficiency was 13%, insufficiency 34%, and sufficiency 53%. Being of African origin (RR 2.68, P = 0.01), Asian origin (RR 3.38, P = < 0.01), or having HIV RNA levels more than 50 copies/ml (RR 1.43, P = 0.04) was associated with an increased risk of low vitamin D level. WLWH with vitamin D deficiency had an increased risk of preterm birth (RR 2.66, P = 0.03) and giving birth to small for gestational age (SGA) children (RR 6.83, P = 0.02) compared with WLWH with sufficient vitamin D level.

CONCLUSION

Low vitamin D level was prevalent among well treated pregnant WLWH in Denmark, especially among women of African or Asian origin, and women with detectable viral loads. Vitamin D deficiency was associated with an increased risk of preterm birth and SGA.

Second-trimester maternal serum vitamin D and pregnancy outcome: The Western Australian Raine cohort study

AIMS

To assess the effect of maternal serum 25(OH)-vitamin D levels during the second trimester of pregnancy on the risk for gestational diabetes (GDM), pregnancy and infantile outcomes.

METHODS

This study is based on the Western Australian Pregnancy Cohort (Raine) study. Maternal serum 25(OH)-vitamin D concentrations of 890 pregnant women were evaluated at 18 weeks pregnancy and grouped into serum Vitamin D quartiles (>30, 30-49, 50-74 and >75 nmol/L).

RESULTS

Participants with de-seasonalized 25 (OH)-vitamin D levels <30 nmol/L were more likely to develop GDM, but not after controlling for ethnicity. Women with high body mass index (BMI) >30 were at a greater risk of developing GDM. Additionally, women with GDM were at a greater risk of primary caesarean delivery. Maternal serum levels of 25(OH)-vitamin D were positively associated with birth weight, body length and head circumference of the neonate.

CONCLUSION

Low maternal serum levels of 25(OH)-vitamin D are associated with GDM gestational diabetes, and race/ethnicity may modify this relationship. High pre-gestational BMI may predict GDM risk. GDM in pregnancy may increase the risk for delivery by caesarean section. Maternal 25(OH)-vitamin D is associated with anthropometric measures of the neonate.

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

Background

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

Objective

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

Design

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

Results

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

Conclusion

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

Vitamin D insufficiency among Danish pregnant women-Prevalence and association with adverse obstetric outcomes and placental vitamin D metabolism

INTRODUCTION

In pregnancy, vitamin D deficiency is associated with increased risk of fetal growth restriction and preeclampsia. The underlying mechanisms are not known, but placental dysfunction is believed to play a role. In a Danish population, where health authorities recommend a 10 µg/day vitamin D supplement during pregnancy, we explored current use of vitamin D supplements and vitamin D status. In term placentas, alterations in vitamin D metabolism and placental growth, evaluated by the key placental growth factor pregnancy-associated plasma protein-A (PAPP-A), and their relation to vitamin D insufficiency were investigated.

MATERIAL AND METHODS

We included 225 randomly selected pregnant women attending a nuchal translucency scan at gestational weeks 11-14. Information on use of vitamin D supplements and body mass index (BMI) at inclusion was obtained using self-reported questionnaires. Plasma 25-hydroxyvitamin D was measured at inclusion and correlated with pregnancy outcomes and placental biology, as judged by expression of PAPP-A and enzymes involved in vitamin D metabolism (CYP24A1, CYP27B1) in term placentas.

RESULTS

Vitamin D supplements were used by 92% of the women, but 42% were vitamin D insufficient (plasma 25-hydroxyvitamin D <75 nmol/L). Eleven women with singleton pregnancies developed fetal growth restriction or preeclampsia. In this small subset, first-trimester mean plasma 25-hydroxyvitamin D was lower in women who developed fetal growth restriction (43 ± 33nmol/L; n = 3; P = .006) and there was a tendency towards lower plasma 25-hydroxyvitamin D among women who developed preeclampsia (65 ± 19 nmol/L; n = 8; P = .08) in third trimester compared with uncomplicated pregnancies (79 ± 22 nmol/L; n = 187). In term placentas, PAPP-A expression was lower among participants with first-trimester vitamin D insufficiency (P = .009; n = 30) but no correlation was found between plasma 25-hydroxyvitamin D and mRNA expression of CYP24A1 (P = .67) and CYP27B1 (P = .34). BMI was negatively correlated with plasma 25-hydroxyvitamin D (P = .03) and positively correlated with placental mRNA expression of CYP24A1 (P = .003; n = 30).

CONCLUSIONS

Despite high compliance with official guidelines regarding vitamin D supplements, vitamin D insufficiency was frequent and the findings indicate that vitamin D insufficiency may affect placental growth. High BMI was associated with vitamin D insufficiency and increased placental vitamin D turnover, but further investigations are needed.

Prevalence of Gestational Diabetes Mellitus in the Middle East and North Africa, 2000-2019: A Systematic Review, Meta-Analysis, and Meta-Regression

Women in the Middle East and North Africa (MENA) region are burdened with several risk factors related to gestational diabetes mellitus (GDM) including overweight and high parity. We systematically reviewed the literature and quantified the weighted prevalence of GDM in MENA at the regional, subregional, and national levels. Studies published from 2000 to 2019 reporting the prevalence of GDM in the MENA region were retrieved and were assessed for their eligibility. Overall and subgroup pooled prevalence of GDM was quantified by random-effects meta-analysis. Sources of heterogeneity were investigated by meta-regression. The risk of bias (RoB) was assessed by the National Heart, Lung, and Blood Institute's tool. One hundred and two research articles with 279,202 tested pregnant women for GDM from 16 MENA countries were included. Most of the research reports sourced from Iran (36.3%) and Saudi Arabia (21.6%), with an overall low RoB. In the 16 countries, the pooled prevalence of GDM was 13.0% (95% confidence interval [CI], 11.5-14.6%, I² , 99.3%). Nationally, GDM was highest in Qatar (20.7%, 95% CI, 15.2-26.7% I² , 99.0%), whereas subregionally, GDM was highest in Gulf Cooperation Council (GCC) countries (14.7%, 95% CI, 13.0-16.5%, I² , 99.0%). The prevalence of GDM was high in pregnant women aged ≥30 years (21.9%, 95% CI, 18.5-25.5%, I² , 97.1%), in their third trimester (20.0%, 95% CI, 13.1-27.9%, I² , 98.8%), and who were obese (17.2%, 95% CI, 12.8-22.0%, I² , 93.8%). The prevalence of GDM was 10.6% (95% CI, 8.1-13.4%, I² , 98.9%) in studies conducted before 2009, whereas it was 14.0% (95% CI, 12.1-16.0%, I² , 99.3%) in studies conducted in or after 2010. Pregnant women in the MENA region are burdened with a substantial prevalence of GDM, particularly in GCC and North African countries. Findings have implications for maternal health in the MENA region and call for advocacy to unify GDM diagnostic criteria.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018100629.

Vitamin D in gestational diabetes mellitus and its association with hyperglycaemia, insulin sensitivity and other factors

We investigated if vitamin D is independently associated with hyperglycaemia in gestational diabetes mellitus (GDM). Serum 25 hydroxy vitamin D (25OHD), fasting blood glucose (FBG), HbA1c, fructosamine, insulin sensitivity (QUICKI equation), body mass index, clothing style and outdoor activity were measured in 58 pregnant women with GDM during the third trimester. 25OHD was also measured in 20 women with normal pregnancies. There was no significant difference in mean 25OHD concentrations between GDM (14.43 ± 5.27 ng/ml) and normal (15.45 ± 5.29 ng/ml) pregnancies, p = .354. However, a higher percentage of GDM subjects had 25OHD concentration <19.8 ng/ml (86 versus 65%, p = .003). 25OHD did not correlate with FBG, HbA1c, fructosamine, insulin sensitivity or insulin dosage (p > .05). On multivariate analysis, only ethnicity (p = .006) and outdoor activity (p = .004) were associated with 25OHD. We conclude that the lower 25OHD levels in our GDM patients were related to ethnicity and outdoor activity (Study FF-2017-111, National University of Malaysia, 16 March 2017).IMPACT STATEMENTWhat is already known on this subject? Vitamin D deficiency in pregnancy is widespread and particularly in certain ethnic groups. Low vitamin D levels may be an aetiological factor for gestational diabetes mellitus (GDM) but previous studies provide conflicting results perhaps due to confounding factors.What do the results of this study add? In this study of pregnant women with GDM from different ethnic backgrounds, we analysed serum 25-hydroxy vitamin D (25OHD) levels together with other confounding factors, that is, body mass index, ethnicity and sunlight exposure. Furthermore, instead of using consensus values, we determined cut-offs for different vitamin D status from normal pregnancies matched for gestational age and ethnicity. We found that a higher percentage of GDM subjects had lower vitamin D status but there was no correlation with hyperglycaemia or insulin sensitivity. The study showed that lower vitamin D levels in GDM was associated with ethnicity and less outdoor activity.What the implications are of these findings for clinical practice and/or further research? In GDM patients, low vitamin D levels may be modifiable by supplementation or lifestyle change. Longitudinal studies are needed to determine whether this would impact on the occurrence of GDM.

The relationship between maternal vitamin D deficiency and glycolipid metabolism and adverse pregnancy outcome

OBJECTIVE

Maternal vitamin D deficiency is associated with glucose and lipid metabolism in the mother and offspring. Meanwhile, it can also lead to adverse pregnancy outcomes. The aim of this case-control study was to document maternal, umbilical arterial glucose and lipid metabolic levels and correlations in pregnancies with or without vitamin D deficiency, while also investigating adverse pregnancy outcomes.

DESIGN/PARTICIPANTS/MEASUREMENTS

A total of 425 pregnant women who received antenatal care and delivered at Wenzhou People's Hospital were enrolled. According to their serum 25-hydroxyvitamin D [25(OH)D] level, the pregnant women were divided into the vitamin D deficiency group [25(OH)D < 20 ng/mL, 185 participants] and the control group [25(OH)D ≥ 20 ng/mL, 240 participants]. Maternal blood samples were collected at 24-28 weeks of gestation and delivery for 75-g oral glucose tolerance test (OGTT), and measurements of glucose and lipid metabolite levels and 25(OH)D levels. Umbilical arterial samples were collected during delivery (33.57-41.43 gestational weeks).

RESULTS

Compared with control participants, vitamin D deficiency women had significantly higher concentrations of fasting blood-glucose (P < .01), 1-h OGTT plasma glucose (P < .01), 2-h OGTT plasma glucose (P < .01), insulin (P < .01), HOMA-IR (P < .01), LDL (P < .01) and triglycerides (P = .02) and lower concentrations of HOMA-S (P < .01). Compared with the control group, vitamin D deficiency women had higher concentrations of triglycerides (P < .01) and lower concentrations of HDL-C (P < .01) and HOMA-β (P = .01) in infant umbilical arterial blood. Pearson's correlation analysis demonstrated that the maternal 25(OH)D level was negatively correlated with maternal plasma glucose, insulin, LDL-C, cholesterol, triglyceride and HOMA-IR (r = -.38, -.27, -.2, -.11, -.11, -.33 and .11; P < .01, <.01, <.01, <.05, <.05 and <.01, respectively), while there was a positive correlation between maternal serum 25(OH)D and HOMA-S (r = .11, P < .05). The triglyceride level in the umbilical artery was negatively correlated with maternal serum 25(OH)D concentration (r = -.286, P < .01), while the HDL-C and HOMA-β in umbilical artery were positively related (r = .154, .103, P < .01). Compared with the control group, the incidences of pre-eclampsia [4.8% (9/185) vs 1.25% (3/240), P = .03], gestational diabetes mellitus [19.45% (36/185) vs 12.08% (29/240), P = .04] and premature rupture of membranes [15.68% (29/185) vs 5.42% (13/240), P < .01] were higher in the vitamin D deficiency group.

CONCLUSION

Vitamin D deficiency during pregnancy is associated with maternal glucose and lipid metabolism and pregnancy outcomes. Therefore, it is worth recommending to maintain vitamin D status at an optimal level in pregnant women to prevent metabolic disorders and pregnancy complications.

Vitamin D and pregnancy outcomes: Overall results of the FEPED study

Vitamin D insufficiency is highly prevalent in children and adults including pregnant women. During pregnancy, maternal vitamin D insufficiency could increase risks of several pregnancy complications and adverse birth outcomes. The FEPED study was designed to assess the effects of maternal vitamin D status in the first trimester during pregnancy on risks of preeclampsia, gestational diabetes mellitus (GDM), preterm birth and small-for-gestational age (SGA) at birth. This observational prospective cohort included 3129 women with a singleton pregnancy between April 2012 and July 2014 in six maternity units in France and Belgium. The aim of this review is to summarize the results of the FEPED study. At the first trimester the mean 25(OH)D concentration was 21.9 ± 10.4 ng/mL and 25(OH)D concentration was <20 ng/mL in 46.5 % of patients. After matching 83 cases of preeclampsia with 319 controls, a significant decrease in the risk of preeclampsia was associated with maternal vitamin D levels ≥ 30 ng/mL in the third trimesters (OR = 0.34; 95 % CI: 0.13-0.86. P = 0.023). In the first trimester, the risk for preeclampsia was decreased in these patients, but did not achieve statistical significance (OR = 0.57 95 % CI, 0.30-1.01; p = 0.09). For the 250 cases with GDM matched with 941 controls, no linear relationship was found between GDM and 25OHD levels in the first trimester of pregnancy. Finally, 2813 pregnant women were included in analyses of risks of preterm and SGA birth. No association was found between low maternal vitamin D levels in the first trimester and the risks of preterm birth (aOR = 1.53; 95 % CI: 0.97-2.43) or SGA (aOR = 1.07; 95 % CI: 0.75-1.54). Further investigation is needed to understand the mechanisms behind the association between vitamin D and birth outcomes.

Hypovitaminosis D Is Associated with Some Metabolic Indices in Gestational Diabetes Mellitus

BACKGROUND

Gestational diabetes mellitus (GDM), a pregnancy complication, is defined as any degree of glucose intolerance with onset or first recognition during pregnancy. Vitamin D deficiency and insufficiency has recently been recognized as a contributing factor to the pathogenesis of GDM, and this link might be associated with hyperglycemia, insulin resistance, and inflammation, which are implicated in GDM.

OBJECTIVES

This study aims at investigating the relationship between vitamin D, fasting plasma glucose (FPG), insulin, zinc, ferritin, and high-sensitivity C-reactive protein (CRP) in GDM.

METHOD

A case-control study in which 80 women attending the antenatal clinic of University College Hospital (UCH), Ibadan, Nigeria, were recruited; the women were grouped into controls (40 nondiabetic pregnant women) and cases (40 pregnant women with GDM). Blood samples were taken at the second trimester, and metabolites were quantified by standard laboratory methods. Student's t test and Pearson correlation were used to compare variables and determine the relationship between variables, respectively.

RESULTS

Results showed significant (p < 0.05) low levels of serum vitamin D and zinc, and significant (p < 0.05) higher levels of FPG and serum insulin, ferritin, and CRP in the GDM group compared to the control group. In the GDM group, a positive weak relationship was observed between vitamin D and zinc (r = 0.18, p < 0.05), while vitamin D was inversely correlated with FPG, serum insulin, ferritin, and CRP (r = -0.23, -0.21, -0.20, -0.46, respectively, p < 0.05).

CONCLUSION

This study suggests that hypovitaminosis D might be associated with glucose intolerance, insulin insensitivity, and inflammation, which are factors implicated in the development and progression of GDM.

Vitamin D Deficiency and Autism Spectrum Disorder

Vitamin D is a neurosteroid hormone crucially involved in neurodevelopment. Neural cell proliferation, neurotransmission, oxidative stress and immune function represent the main mechanisms mediated by vitamin D in the Central Nervous System. Therefore, its deficiency during pregnancy and early childhood may significantly impact on a developing brain, leading to possible adverse neuropsychological outcomes including Autism Spectrum Disorder (ASD). Significant vitamin D deficiency is described within children affected by ASD and in pregnant mothers whose offspring will later develop ASD, suggesting a possible role of the hormone as a contributing risk factor in the etiopathogenesis of ASD. We reviewed the actual literature on the potential contributing role of prenatal and early postnatal vitamin D deficiency in ASD etiopathogenesis, at both genetic and environmental levels, and the possible effect of vitamin D supplementation in autistic children. Conflicting but promising results emerged on the topic. Further Randomized Controlled Trials studies carried out during pregnancy and early infancy are necessary for better understanding the possible contribution of vitamin D deficiency in the etiopathogenesis of autism and the potential efficacy of the hormone supplementation in the improvement of ASD core symptoms.

Vitamin D Deficiency at Mid-Pregnancy Is Associated with a Higher Risk of Postpartum Glucose Intolerance in Women with Gestational Diabetes Mellitus

BACKGROUND

To evaluate the association between serum 25-hydroxyvitamin D (25(OH)D) at mid-pregnancy and postpartum glucose intolerance in women with gestational diabetes mellitus (GDM).

METHODS

We enrolled 348 pregnant women diagnosed with GDM from August 2012 to October 2016. We measured serum 25(OH)D levels at mid-pregnancy and carried out a 75-g oral glucose tolerance test at 6 to 12 weeks after delivery. Vitamin D deficiency was defined as serum 25(OH)D <20 ng/mL.

RESULTS

The prevalence of vitamin D deficiency was 76.7% (n=267). Women with vitamin D deficiency had a higher prevalence of postpartum glucose intolerance than did those without vitamin D deficiency (48.7% vs. 32.1%, P=0.011). Serum 25(OH)D level was negatively correlated with hemoglobin A1c at antepartum and postpartum period (antepartum: r=-0.186, P=0.001; postpartum: r=-0.129, P=0.047). Homeostasis model assessment of β-cell function was positively correlated with serum 25(OH)D level only postpartum (r=0.138, P=0.035). The risk of postpartum glucose intolerance was 2.00 times (95% confidence interval, 1.13 to 3.55) higher in women with vitamin D deficiency than in those without vitamin D deficiency (P=0.018).

CONCLUSION

In women with GDM, vitamin D deficiency at mid-pregnancy is associated with an elevated risk of postpartum glucose intolerance.

Association between standardized vitamin 25(OH)D and dyslipidemia: a community-based study in Riyadh, Saudi Arabia

BACKGROUND

Vitamin D deficiency associated with dyslipidemia can contribute towards cardiovascular diseases. Previous studies have found that Saudi Arabia has a high burden of vitamin D deficiency and cardiovascular disease risk factors. We aimed to explore the relationship between vitamin D deficiency and dyslipidemia, including total cholesterol, low-density lipids, high-density lipids (HDL), and triglycerides (TG) in apparently healthy Saudi male and female participants aged 30-75 years.

METHODS

A cross-sectional study was conducted on 1717 apparently healthy Saudi participants from 18 primary health care centers in Riyadh. Data collectors conducted the interviews, took anthropometric measurements, and collected the blood samples. Serum 25-hydroxyvitamin vitamin D (25(OH)D) levels were measured using an electrochemiluminescence assay method. Lipid panel was measured by a fully automated analyzer using enzymatic methods.

RESULTS

Multivariable logistic regression analysis revealed that the adjusted odds ratio (ORA) of low level of HDL cholesterol in association with 25(OH)D deficiency was 2.1 times higher in males (ORA = 2.1; 95% CI = 1.1, 3.9) and 1.3 times higher in females (ORA = 1.3; 95% CI = 0.9, 1.9). A significant excess odds ratio of high levels of TG in association with 25(OH) D deficiency was observed in females (ORA = 3.0; 95% CI = 1.1, 7.9) but not in males.

CONCLUSION

Vitamin D deficiency is highly prevalent in Saudi Arabia. Low levels of HDL cholesterol in men and high TG levels in women are associated with vitamin D deficiency. The results emphasize the importance of treating vitamin D deficiency in the general population.

Serum vitamin D deficiency and risk of gestational diabetes mellitus: a meta-analysis

INTRODUCTION

This meta-analysis was performed to confirm the relationship of gestational diabetes mellitus (GDM) and vitamin D.

MATERIAL AND METHODS

PubMed and CNKI databases were searched for relevant articles. Standard mean difference (SMD) along with 95% CI was used to compare vitamin D level between women with GDM and healthy subjects. The correlation coefficient between the vitamin D and homeostasis model assessment-insulin resistance index (HOMA-IR) was analyzed.

RESULTS

The vitamin D level of GDM subjects was much lower than healthy subjects (SMD = -0.71, 95% CI: -0.91, -0.50). Vitamin D deficiency was associated with high risk of GDM (OR = 1.15, 95% CI: 1.07-1.23). Vitamin D was negatively correlated with HOMA-IR (r = -0.62, 95% CI: -0.85, -0.39). The analysis showed no publication bias (Egger's: p = 0.197; Begg's: p = 0.786).

CONCLUSIONS

Vitamin D is closely associated with the onset of GDM.

Calcifediol Decreases Interleukin-6 Secretion by Cultured Human Trophoblasts From GDM Pregnancies

Gestational diabetes mellitus (GDM) is often characterized by low maternal calcifediol (25OHD) and high inflammation levels. This study aimed to determine whether placental protein expressions of CYP27B1, vitamin D receptor (VDR), and CYP24A1 are impaired in GDM and to investigate the effect of a 25OHD treatment on IL-6 secretion by GDM trophoblasts compared with normoglycemic (NG) trophoblasts. Placental tissue samples were harvested to determine protein expression of CYP27B1, VDR, and CYP24A1 by immunoblots. Isolated trophoblasts were stimulated with 25OHD concentrations (25 to 2000 nM) once a day for 3 days and IL-6 secretion was quantified (ELISA). We recruited 17 NG women, 19 women with GDM treated with diet and exercise alone (GDM-d) and 9 women with GDM who necessitated insulin therapy (GDM-i). Protein expressions of CYP27B1 and VDR were significantly higher in placental tissue from GDM-d women compared with NG women (both P = 0.02), whereas no differences were detected between GDM-i and NG placental tissues. In cultured trophoblasts (two groups; n = 5 NG and n = 5 GDM-d), exposure to increasing 25OHD concentrations significantly decreased IL-6 secretion in the GDM-d group only (P = 0.006). After treatment with 25OHD (2000 nM), IL-6 secretion was lower in the GDM-d group compared with the NG group (P = 0.03). Our results suggest an upregulation of the VDR-1,25(OH)2D complex bioavailability in GDM-d placentas, possibly reflecting a compensatory mechanism aiming to ensure that vitamin D can exert its genomic and nongenomic effects in the target cells of the placental-fetal unit. Our findings support an anti-inflammatory effect of vitamin D at the feto-maternal interface in GDM-d pregnancies.

The prevalence of hypovitaminosis D and its risk factors in pregnant women and their newborns in the Middle East: A systematic review

BACKGROUND

Pregnant women and newborns are at risk for vitamin D deficiency (VDD). Also, poor health outcomes for pregnant women with VDD are reported in the published literature.

OBJECTIVE

The aim of this systematic review was to estimate the prevalence of hypovitaminosis D and the associated risk factors for hypovitaminosis D in Middle Eastern pregnant women and their newborns.

RESULTS

The prevalence of circulating 25-hydroxyvitamin D (25(OH)D) < 50 nmol/L as a marker of vitamin D status in pregnant women and their newborns was between 24.5-98% and 22-100%, respectively. The prevalence of 25(OH) D < 25 nmol/L in pregnant women and their newborns was over a wide range between 16.7-80% and 22-82%, respectively. Predictors for low maternal and neonatal 25(OH)D concentrations included decreased vitamin D synthesis due to reduced exposure to sunlight and decreased nutritional intake of vitamin D. A predictor of low neonatal 25(OH)D concentrations included maternal vitamin D status and the correlation between vitamin D concentrations in maternal and cord blood.

CONCLUSION

The high prevalence of VDD in the pregnant women of the Middle East underscores the necessity of implementing national prevention and intervention strategies. A clear policy for clinicians and healthcare workers is needed for screening and maintaining sufficient vitamin D status during pregnancy.

Significance of Vitamin D on the Susceptibility of Gestational Diabetes Mellitus - A Meta-Analysis

Vitamin D plays an important role in glucose tolerance by stimulating insulin secretion and evidences suggest a contradictory result on the association between vitamin D status and risk of developing gestational diabetes mellitus (GDM). The present updated meta-analysis has been undertaken to find out the joined effect of vitamin D status on the risk of effect GDM considering previously published articles. Data were collected through literature search using electronic databases to retrieve relevant published research articles using various combinations of the following keywords, "vitamin D," "vitamin D deficiency," "cholecalciferol," "25-hydroxyvitamin D," "25(OH) D," "gestational diabetes mellitus," and "GDM." A total of 36 studies including 7,596 GDM cases and 23,377 non-GDM controls were involved in this study. Overall, pooled meta-analysis showed that pregnant women diagnosed with GDM have 18% higher risk of GDM risk when compared with controls [odds ratio (OR) = 1.18, 95% confidence interval (CI) 1.10-1.25; P = 0.00] with high heterogeneity (I² = 73.29). The mean difference was also significantly different between cases and controls (OR = -0.18, 95% CI - 0.22 to - 0.14; P = 0.00). Subgroup analysis showed significant results with age more than 30 years, Asian and European regions, and case-control, cross-sectional, and nested case-control study design. Low concentration of vitamin D is associated with the development of GDM. Although in future more studies especially systematically designed clinical trials based on vitamin D supplementation with large sample size on different population are needed to elucidate the exact concentration of vitamin D during pregnancy as well as before and after pregnancy.

Relationship of Early Vitamin D Concentrations and Gestational Diabetes Mellitus in Indian Pregnant Women

Background: A high prevalence of vitamin D deficiency exists in pregnant Indian women (~90%). Increasing evidence suggests that vitamin D could play a pivotal role in maintaining normal glucose homeostasis. We aimed to determine the association between maternal vitamin D concentrations in early pregnancy and the risk of gestational diabetes mellitus (GDM). Methods: A prospective observational study was conducted on healthy pregnant women (n = 392) attending routine antenatal care at St. John's Medical College Hospital, Bangalore recruited at ~12 weeks of gestation. At baseline, details on socio-economic status, obstetric history, dietary intakes, and anthropometry were collected. Venous plasma total vitamin D concentration was assessed using tandem liquid chromatography mass spectrophotometry (LC-MS/MS). Oral glucose tolerance test (OGTT) at recruitment, followed by glucose tolerance test (GTT) at mid-pregnancy was conducted. GDM was diagnosed and confirmed using the International Association of Diabetes and Pregnancy Study Groups (IADPSG) classification. Univariate and adjusted logistic regression models were used to evaluate the associations between total vitamin D concentrations at enrollment with GDM. Results: Of the cohort, 10.2% were diagnosed as GDM. Women with GDM were older (26 vs. 24 years) and heavier (51.6 vs. 51.2 kg) compared to the rest. A higher prevalence of GDM was observed among women with 1st trimester plasma total vitamin D in the lowest quartile (≤23.6 nmol/L) compared to the subjects in the other three quartiles (16.1 vs. 8.6%, p = 0.033). Adjusted multivariable regression analysis showed that women in the lowest quartile of plasma total vitamin D had twice the odds of GDM compared to women belonging to the remaining quartiles [OR = 2.32 (95%CI: 1.10, 4.91), p = 0.028]. Conclusions: Low plasma total vitamin D concentrations in early pregnancy may be associated with a higher risk of GDM.

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.

Efficacy of vitamin D supplementation in gestational diabetes mellitus: Systematic review and meta-analysis of randomized trials

BACKGROUND

Trials have examined on the benefits of vitamin D supplementation in pregnant women.

OBJECTIVE

This review aimed to evaluate whether oral vitamin D supplements, when given to pregnant women with gestational diabetes mellitus (GDM), would improve maternal and neonatal outcomes, compared with no treatment or placebo.

METHOD

We performed a systematic review following Cochrane methodology, and randomized trials were included where pregnant women with GDM received vitamin D supplementation versus placebo/no treatment or vitamin D and calcium versus placebo/no treatment. Primary outcomes were preeclampsia, preterm birth, cesarean delivery, gestational hypertension, and adverse events related to vitamin D supplementation. The search strategies were applied to the following databases: MEDLINE, Embase, LILACS, and CENTRAL. Similar outcomes in at least two trials were plotted using Review Manager 5.3 software. The quality of evidence was generated according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

The total of 1224 references were identified, eleven trials were potentially eligible, and six were included in this review (totaling 456 women). The meta-analysis of frequency of cesarean deliveries did not show significant differences between groups, none of the trials evaluated the remaining primary outcomes. For secondary outcomes, our results suggest that vitamin D supplementation in pregnant women with GDM may reduce newborn complications such as hyperbilirubinemia, polyhydramnios (RR: 0.40, 95% CI: 0.23 to 0.68; RR: 0.17, 95% CI: 0.03 to 0.89; respectively), and the need for maternal or infant hospitalization (RR: 0.13; 95% CI: 0.02 to 0.98; RR: 0.40, 95% CI: 0.23 to 0.69). However, the evidence was of low or very low quality.

CONCLUSION

We did not find moderate or high quality evidence indicating that vitamin D supplementation, when compared with placebo, improves glucose metabolism, adverse maternal and neonatal outcomes related to GDM in pregnant women.

Severe 25(OH)vitamin-D deficiency: A risk factor for development of gestational diabetes mellitus

OBJECTIVE

To estimate the level of 25 (OH)vitamin D in gestational diabetes mellitus (GDM) and to find the correlation between level of 25(OH)vitamin D and GDM.

MATERIALS AND METHODS

The study was conducted on 50 diagnosed patients of GDM attending antenatal clinic in the obstetrics and gynecology department of Pt. B.D. Sharma PGIMS, Rohtak. 50 age and gestational age matched normoglycemic women were taken as control group. Procedure of study was explained to the participants and informed consent was taken.

RESULTS

GDM women had higher age, BMI, and positive family history of type 2 DM as compared to pregnant women without GDM. The mean vitamin D in GDM women was 32.64 ± 24.33 nmol/L while in controls it was 39.90 ± 21.86 nmol/L(P = 0.033). The prevalence of severe vitamin D deficiency(<25 nmol/L) was found to be 44% among GDM women (22 out of 50 GDM women) and 20% among women with normoglycemia (10 out of 50 normoglycemic controls) with significant p value of 0.010 and odds ratio of 1.833. GDM women with BMI>25 kg/m² had 1.799 times chances to be severely deficit in vitamin D than women with BMI<25 kg/m² 6 GDM women had mild vitamin D deficiency (>50 but <75 nmol/L) and 16 had moderate deficiency (>25 but <50 nmol/L). Only 6 GDM patients were found to be sufficient for vitamin D(>75 nmol/L).

CONCLUSION

Severe vitamin D deficiency in second trimester of pregnancy is significantly associated with elevated risk for GDM.

Studying the relation between vitamin D deficiency and glycemic state among pregnant women with gestational diabetes

AIM

This study was conducted to illustrate the relation between vitamin D deficiency and glycemic parameters.

MATERIALS AND METHODS

The study was carried out on 80 pregnant females who were attending obstetrics and gynecology out-patient clinic in el-Shatby hospital in Alexandria university, Egypt. They were divided into 2 groups: group 1 (n = 40) pregnant females diagnosed with gestational diabetes de novo at week 24-28 and group 2 (n = 40) pregnant females of the same age group who were not suffering from any glucose intolerance (control group). Each patient was subjected to detailed history taking, complete physical examination, One step 75 gm Oral glucose tolerance test, insulin, glycated hemoglobin(HbA1c),homeostatic model assessment of insulin resistance(HOMA-IR), 25 hydroxy-vitamin D, serum calcium, phosphorous and parathormone were assessed.

RESULTS

A statistically significant higher fasting blood glucose (FBG), HbA1c%, fasting insulin and HOMA-IR was observed in patients with Gestational diabetes mellitus (GDM) versus control (p < 0.001). However, no significant difference was observed as regards Vitamin D levels in patients with GDM and control group. Among patients with GDM, vitamin D was found to correlate negatively with HbA1c (p < 0.001), insulin(p = 0.019) and HOMA-IR(p = 0.034).

CONCLUSION

No definite causal relationship was observed between low vitamin D and subsequent occurrence of GDM.however, a significant correlation was found between the degree of vitamin D deficiency and the insulin resistance in patients with GDM.

Disparities in the timing and measurement methods to assess vitamin D status during pregnancy: A Narrative Review

Studies that examined associations between low circulating 25-hydroxyvitamin D (25(OH)D) and adverse pregnancy outcomes used various designs, assay methods and time points for measurement of 25(OH)D concentrations, which creates some confusion in the current literature. We aimed to investigate the variability in the timing and measurement methods used to evaluate vitamin D status during pregnancy. Analysis of 198 studies published between 1976 and 2017 showed an important variability in the choice of 1) threshold values for 25(OH)D insufficiency or deficiency, 2) 25(OH)D measurement methods, and 3) trimester in which 25(OH)D concentrations were measured. Blood samples were taken once during pregnancy in a large majority of studies, which may not be representative of vitamin D status throughout pregnancy. Most studies reported adjustment for confounding factors including season of blood sampling, but very few studies used the 25(OH)D gold standard assay, the LC-MS/MS. Prospective studies assessing maternal 25(OH)D concentrations 1) by standardized and validated methods, 2) at various time points during pregnancy, and 3) after considering potential confounding factors, are needed.

High Prevalence of Maternal Serum 25-Hydroxyvitamin D Deficiency Is Not Associated With Poor Birth Outcomes Among Healthy White Women in the Pacific Northwest

OBJECTIVE

To quantify vitamin D status among pregnant women in the Pacific Northwest (Portland, OR, and Seattle, WA) and examine pregnancy and newborn outcomes in relationship to maternal serum blood samples obtained during pregnancy.

DESIGN

A retrospective cohort design.

SETTING

Data from 2009 to 2013 were abstracted from the health records of two out-of-hospital midwifery practices in the Pacific Northwest.

PARTICIPANTS

Women with recorded serum blood samples for vitamin D during pregnancy were included. We reviewed health records of 663 women, and 357 met criteria.

METHODS

We extracted demographic, biometric, and pregnancy outcome data from participants' records and analyzed them using regression models.

RESULTS

Mean serum 25-hydroxy vitamin D (25[OH]D) was 29.96 ± 10.9 ng/ml; 45.5% of participants were sufficient (≥30 ng/ml), and 55.5% were insufficient or deficient (<29 ng/ml). Lower vitamin D levels were predicted by Seattle location, greater prepregnancy body mass index, and blood samples drawn during the winter. Vitamin D status was not a predictor of spontaneous abortion, glucose tolerance test result, cesarean birth, infant birth weight, or any other outcome investigated.

CONCLUSION

Although there is a high prevalence of vitamin D insufficiency and deficiency in pregnant women in the Pacific Northwest, adverse health effects were not observed. This may be attributable to the overall healthy profile of the women in our sample. Further research on maternal vitamin D status should focus on identification of optimal vitamin D levels in pregnancy and long-term outcomes among offspring of women who are vitamin D deficient, particularly those from high-risk, vulnerable populations.

Avoiding maternal vitamin D deficiency may lower blood glucose in pregnancy

BACKGROUND

Vitamin D status is hypothesised to play a role in gestational glucose control. No studies to date have examined vitamin D in relation to changes in blood glucose in pregnancy. Thus, the aim was to examine if vitamin D in early pregnancy and vitamin D trajectory associate with blood glucose trajectory over pregnancy in a Swedish cohort. We also investigated the relation between maternal vitamin D status and excessive fetal growth.

METHODS

In 2013-2014, pregnant women were recruited to the GraviD cohort study when registering at the antenatal clinics in south-west Sweden. In the present analysis, 1928 women were included. Women with preexisting diabetes and multifetal pregnancy were excluded. Random blood glucose was assessed according to routine practice, in first trimester (T1, gestational week 4-16), second trimester (T2, gestational week 17-27), early (T3a, gestational week 28-35) and late third trimester (T3b, gestational week 36-41). In T1 and T3a, serum 25-hydroxyvitamim D (25OHD) was analyzed by liquid chromatography tandem mass spectrometry. Large for gestational age (LGA), as a proxy of excessive fetal growth, was defined as body weight at birth above 2 standard deviations of the gender specific population mean. Adjusted linear regression, linear mixed models analysis and logistic regression analysis were used to study 25OHD in relation to T1 blood glucose, glucose trajectory and LGA, respectively.

RESULTS

Mean blood glucose increased during pregnancy (5.21 mmol/L in T1, 5.27 mmol/L in T2, 5.31 mmol/L in T3a and 5.34 mmol/L in T3b; p = 0.003). In T1, 25OHD was negatively associated with blood glucose, i.e. 25OHD ≥ 30 nmol/L was associated with 0.25-0.35 mmol/L lower glucose. T1 25OHD was also negatively associated with blood glucose trajectory. Higher T3 25OHD was associated with higher odds of LGA (p = 0.032).

CONCLUSION

Avoiding maternal vitamin D deficiency in early pregnancy is associated with lower blood glucose in early pregnancy and throughout pregnancy. Higher 25OHD in late pregnancy was associated with higher odds of LGA at birth.

The role of vitamin D in perinatology. An up-to-date review

The role of vitamin D in perinatology is a subject of major interest in current medicine. There is growing evidence about the role of maternal vitamin D levels in pregnancy outcomes. The aim of this review is to summarize the current literature about the role of vitamin D in perinatology. Evidence from this review suggests associations between low levels of maternal vitamin D and higher risk of certain obstetrical complications. Vitamin D has been found to be related to preeclampsia, gestational diabetes mellitus, low birth weight, and preterm birth. The current literature supports vitamin D supplementation in pregnant women, but more high-quality data are necessary. The problem that remains is how to achieve an optimal 25-hydroxyvitamin D level. To determine the real benefits of vitamin D supplementation in pregnancy, we need high-quality trials in larger groups.

Comprehensive Review on Diabetes Associated Cardiovascular Complications - The Vitamin D Perspective

Vitamin D, a steroid hormone is primarily known for its role in calcium and bone mineral homeostasis. Over the years, vitamin D has been implicated in various non-skeletal diseases. The extraskeletal phenomenon can be attributed to the presence of vitamin D receptors (VDRs) in almost all cells and identification of 1-α hydroxylase in extrarenal tissues. The vitamin D deficiency (VDD) pandemic was globally reported with increasing evidence and paralleled the prevalence of diabetes, obesity and cardiovascular diseases (CVDs). A dependent link was proposed between hypovitaminosis D glycemic status, insulin resistance and also the other major factors associated with type 2 diabetes leading to CVDs. Insulin resistance plays a central role in both type 2 diabetes and insulin resistance syndrome. These 2 disorders are associated with distinct etiologies including hypertension, atherogenic dyslipidemia, and significant vascular abnormalities that could lead to endothelial dysfunction. Evidence from randomised clinical trials and meta-analysis, however, yielded conflicting results. This review summarizes the role of vitamin D in the regulation of glucose homeostasis with an emphasis on insulin resistance, blood pressure, dyslipidaemia, endothelial dysfunction and related cardiovascular diseases and also underline the plausible mechanisms for all the documented effects.

The Relationship Between Vitamin D Deficiency and Insulin Resistance in Pregnant Women with Gestational Diabetes

BACKGROUND

Diabetes Mellitus is one of the most common medical disorders in pregnancy. The possibility of vitamin D deficiency as a pathogenesis for impaired glucose tolerance tests show a probable role of vitamin D in insulin secretion and reduction of insulin resistance. This study was assigned to evaluate relation between serum vitamin D level and insulin resistance in Gestational Diabetes Mellitus (GDM).

METHODS

This cross sectional study was done throughout one year between 2015-2016 in GDM patients (age, 20-40 years). After history taking and physical examination, the laboratory tests including : Fasting Blood Sugar (FBS), Glucose Tolerance Test (GTT), calcium, phosphorous, parathormone, 25(OH) vitamin D, insulin, HbA1C, TG, LDL, HDL were performed for all patients. Insulin resistance was calculated according to HOMA-IR formula. Vitamin D level was compared between patients with and without insulin resistance.

RESULTS

This research was performed in 93 GDM patients with average age (30.3 ± 5.6). Thirty eight patients with insulin resistance and 55 patients without insulin resistance were detected. The prevalence of vitamin D deficiency was 91.4% in all patients. There was no significant difference in vitamin D levels between insulin resistant and non insulin resistant group (P-value=0.51). In all variable parameters, only FBS and triglyceride level in insulin resistant group were more than non insulin resistant group (P-value<0.05).

CONCLUSION

Obtained results showed not significant relationship between vitamin D deficiency and insulin resistance in GDM patients.

Histone H3 lysine 9 acetylation is downregulated in GDM Placentas and Calcitriol supplementation enhanced this effect

Despite the ever-rising incidence of Gestational Diabetes Mellitus (GDM) and its implications for long-term health of mothers and offspring, the underlying molecular mechanisms remain to be elucidated. To contribute to this, the present study's objectives are to conduct a sex-specific analysis of active histone modifications in placentas affected by GDM and to investigate the effect of calcitriol on trophoblast cell's transcriptional status. The expression of Histone H3 lysine 9 acetylation (H3K9ac) and Histone H3 lysine 4 trimethylation (H3K4me3) was evaluated in 40 control and 40 GDM (20 male and 20 female each) placentas using immunohistochemistry and immunofluorescence. The choriocarcinoma cell line BeWo and primary human villous trophoblast cells were treated with calcitriol (48 h). Thereafter, western blots were used to quantify concentrations of H3K9ac and the transcription factor FOXO1. H3K9ac expression was downregulated in GDM placentas, while H3K4me3 expression was not significantly different. Cell culture experiments showed a slight downregulation of H3K9ac after calcitriol stimulation at the highest concentration. FOXO1 expression showed a dose-dependent increase. Our data supports previous research suggesting that epigenetic dysregulations play a key role in gestational diabetes mellitus. Insufficient transcriptional activity may be part of its pathophysiology and this cannot be rescued by calcitriol.

Biomarker potential of C-peptide for screening of insulin resistance in diabetic and non-diabetic individuals

Insulin resistance is a hallmark feature of type-2 diabetes mellitus (T2DM). We determined the homeostatic model assessment insulin resistance (HOMA-IR) and evaluated its association with C-peptide, insulin, fasting blood glucose (FBG) and glycated hemoglobin (HbA1c) in T2DM patients and non-diabetic subjects. This study comprised a total of 47 T2DM patients and 38 non-diabetic controls. Venous blood samples from all the subjects were collected and sera were analyzed for FBG, HbA1c, insulin and C-peptide using an autoanalyzer. HOMA-IR was calculated using the following equation: HOMA-IR = fasting insulin (µU/ml) × fasting glucose (mmol/L)/22.5. There was a significant increase in the levels of FBG and HbA1c in diabetic patients. Although the levels of C-peptide and insulin did not differ significantly between the two groups, a significant increase in HOMA-IR was observed in T2DM patients. Both insulin and C-peptide were significantly correlated with HOMA-IR. In conclusion, C-peptide may serve as a simple and convenient predictor of HOMA-IR.

Effectiveness of Prenatal Vitamin D Deficiency Screening and Treatment Program: A Stratified Randomized Field Trial

CONTEXT

Despite evidence on the association between hypovitaminosis D and adverse pregnancy outcomes and the positive impact of vitamin D supplementation, no evidence exists supporting a universal screening program in pregnancy as part of routine prenatal care.

OBJECTIVE

We sought to determine the effectiveness of a prenatal screening program on optimizing 25-hydroxyvitamin D [25(OH)D] levels and preventing pregnancy complications. Also, to identify a safe regimen, we compared several regimens in a subgroup of vitamin D-deficient pregnant women.

DESIGN

Two cities of Masjed-Soleyman and Shushtar from Khuzestan province, Iran, were selected as the screening and nonscreening arms, respectively. Within the screening arm, a randomized controlled trial was conducted on 800 pregnant women.

SETTING

Health centers of Masjed-Soleyman and Shushtar cities.

PATIENTS OR PARTICIPANTS

Pregnant women aged 18 to 40 years.

INTERVENTION

Women with moderate [25(OH)D, 10 to 20 ng/mL] and severe [25(OH)D, <10 ng/mL] deficiency were randomly divided into four subgroups and received vitamin D3 (D3) until delivery.

MAIN OUTCOME MEASURE

Maternal concentration of 25(OH)D at delivery and rate of pregnancy complications.

RESULTS

After supplementation, only 2% of the women in the nonscreening site met the sufficiency level (>20 ng/mL) vs 53% of the women in the screening site. Adverse pregnancy outcomes, including preeclampsia, gestational diabetes mellitus, and preterm delivery, were decreased by 60%, 50%, and 40%, respectively, in the screening site. A D3 injection in addition to monthly 50,000 IU maintenance therapy contributed the most to achievement of sufficient levels at delivery.

CONCLUSIONS

A prenatal vitamin D screening and treatment program is an effective approach in detecting deficient women, improving 25(OH)D levels, and decreasing pregnancy adverse outcomes.

The Association of Vitamin D Levels with Common Pregnancy Complications

The association between vitamin D deficiency and various adverse pregnancy outcomes has been extensively investigated in recent years. The pregnant woman is the only source of vitamin D for the foetus. The main sources of vitamin D for pregnant women are sunlight, fortified dairy products, oily fish and dietary supplements. Vitamin D deficiency during pregnancy has been associated with some adverse neonatal outcomes as well as an increased risk of late pregnancy complications. The outcomes of the published studies investigating preeclampsia and gestational diabetes mellitus vary with some large trials suggesting a potential positive effect of vitamin D supplementation during pregnancy on the decreased risk of these complications. Research also suggests a possible connection between lower vitamin D concentrations and increased risk of preterm labour. In our manuscript, we aim to review the existing literature regarding the prevalence of vitamin D deficiency during pregnancy, the factors associated with vitamin D deficiency, and possible pregnancy complications arising from it.

Impact of vitamin D on pregnancy-related disorders and on offspring outcome

Observational studies from all over the world continue to find high prevalence rates of vitamin D insufficiency and deficiency in many populations, including pregnant women. Beyond its classical function as a regulator of calcium and phosphate metabolism, vitamin D elicits numerous effects in the human body. Current evidence highlights a vital role of vitamin D in mammalian gestation. During pregnancy, adaptations in maternal vitamin D metabolism lead to a physiologic increase of vitamin D levels, mainly because of an increased renal production, although other potential sources like the placenta are being discussed. A sufficient supply of mother and child with calcium and vitamin D during pregnancy ensures a healthy bone development of the fetus, whereas lack of either of these nutrients can lead to the development of rickets in the child. Moreover, vitamin D insufficiency during pregnancy has consistently been associated with adverse maternal and neonatal pregnancy outcomes. In multitudinous studies, low maternal vitamin D status was associated with a higher risk for preeclampsia, gestational diabetes mellitus and other gestational diseases. Likewise, several negative consequences for the fetus have been reported, including fetal growth restriction, increased risk of preterm birth and a changed susceptibility for later-life diseases. However, study results are diverging and causality has not been proven so far. Meta-analyses on the relationship between maternal vitamin D status and pregnancy outcomes revealed a wide heterogeneity of studied populations and the applied methodology in vitamin D assessment. Until today, clinical guidelines for supplementation cannot be based on high-quality evidence and it is not clear if the required intake for pregnant women differs from non-pregnant women. Long-term safety data of vitamin D supplementation in pregnant women has not been established and overdosing of vitamin D might have unfavorable effects, especially in mothers and newborns with mutations of genes involved in vitamin D metabolism. Reliable data from large observational and interventional randomized control trials are urgently needed as a basis for any detailed and safe recommendations for supplementation in the general population and, most importantly, in pregnant women. This is of utmost importance, as ensuring a sufficient vitamin D-supply of mother and child implies a great potential for the prevention of birth complications and development of diseases.