Vitamin D levels in an Australian and New Zealand cohort and the association with pregnancy outcome

Associations Between Prenatal Vitamin D and Placental Gene Expression

Background

Vitamin D is a hormone regulating gene transcription. Prenatal vitamin D has been linked to immune and vascular function in the placenta, a key organ of pregnancy. To date, studies of vitamin D and placental gene expression have focused on a limited number of candidate genes. Transcriptome-wide RNA sequencing can provide a more complete representation of the placental effects of vitamin D.

Objective

We investigated the association between prenatal vitamin D levels and placental gene expression in a large, prospective pregnancy cohort.

Methods

Participants were recruited in Shelby County, Tennessee in the Conditions Affecting Neurocognitive Development and Learning in Early childhood (CANDLE) study. Vitamin D level (plasma total 25-hydroxyvitatmin D, [25(OH)D]) was measured at mid-pregnancy (16-28 weeks' gestation) and delivery. Placenta samples were collected at birth. RNA was isolated and sequenced. We identified differentially expressed genes (DEGs) using adjusted linear regression models. We also conducted weighted gene co-expression network analysis (WGCNA).

Results

The median 25(OH)D of participants was 21.8 ng/mL at mid-pregnancy (N=774, IQR: 15.4-26.5 ng/mL) and 23.6 ng/mL at delivery (N=753, IQR: 16.8-29.1 ng/mL). Placental expression of 25 DEGs was associated with 25(OH)D at mid-pregnancy, but no DEG was associated with 25(OH)D at delivery. DEGs were related to energy metabolism, cytoskeletal function, and RNA transcription. Using WGCNA, we identified 2 gene modules whose expression was associated with 25(OH)D at mid-pregnancy and 1 module associated with 25(OH)D at delivery. These modules were enriched for genes related to mitochondrial and cytoskeletal function, and were regulated by transcription factors including ARNT2, BHLHE40, FOSL2, JUND, and NFKB1.

Conclusions

Our results indicate that 25(OH)D during mid-pregnancy, but not at delivery, is associated with placental gene expression at birth. Future research is needed to investigate a potential role of vitamin D in programming placental mitochondrial metabolism, intracellular transport, and transcriptional regulation during pregnancy.

Mushrooms: a food-based solution to vitamin D deficiency to include in dietary guidelines

Vitamin D deficiency and insufficiency is a public health issue, with low dietary vitamin D intakes a contributing factor. Rates of vitamin D deficiency are 31% in Australia, and up to 72% in some regions globally. While supplementation is often prescribed as an alternative to additional sun exposure, complementary approaches including food-based solutions are needed. Yet, food-centric dietary guidelines are not always adequate for meeting vitamin D needs. Edible mushrooms such as Agaricus bisporus can produce over 100% of vitamin D recommendations (10 μg/day, Institute of Medicine) per 75 g serve (18 μg) on exposure to UV-light, with the vitamin D2 produced showing good stability during cooking and processing. However, mushrooms are overlooked as a vitamin D source in dietary guidelines. Our dietary modelling shows that four serves/week of UV-exposed button mushrooms can support most Australian adults in meeting vitamin D recommendations, and UV-exposed mushrooms have been found to increase vitamin D status in deficient individuals. While recent evidence suggests some differences between vitamin D2 and vitamin D3 in physiological activities, vitamin D2 from mushrooms can be part of a larger solution to increasing dietary vitamin D intakes, as well as an important focus for public health policy. Mushrooms exposed to UV represent an important tool in the strategic toolkit for addressing vitamin D deficiency in Australia and globally. Health authorities lead the recognition and promotion of mushrooms as a natural, vegan, safe, and sustainable vitamin D food source.

Maternal vitamin D status and risk of gestational diabetes mellitus in twin pregnancies: a longitudinal twin pregnancies birth cohort study

BACKGROUND

Gestational diabetes mellitus (GDM) is a common complication of pregnancy, with significant short-term and long-term implications for both mothers and their offspring. Previous studies have indicated the potential benefits of vitamin D in reducing the risk of GDM, yet little is known about this association in twin pregnancies. This study aimed to investigate maternal vitamin D status in the second trimester and examine its association with the risk of GDM in twin pregnancies.

METHODS

We conducted a prospective cohort study based on data from the Chongqing Longitudinal Twin Study (LoTiS). Peripheral blood serum was collected from the mothers in the second trimester to measure 25(OH)D concentrations. GDM was diagnosed at 23-26 weeks of gestation using a 75-g 2-h oral glucose tolerance test. We used multivariable logistic regression analyses to examine the correlations between vitamin D status and the risk of GDM.

RESULTS

Of the total participants, 93 (29.9%) women were diagnosed with GDM. The mean serum 25(OH)D concentration in the second trimester was 31.1 ± 11.2 ng/mL, and the rate of vitamin D insufficiency and deficiency were 23.5% and 18.7%, respectively. Compared to women with a 25(OH)D concentration < 30 ng/mL, those with a 25(OH)D concentration ≥ 30 ng/mL had a significantly lower risk of GDM (RR 0.61; 95% CI: 0.43, 0.86), especially those who were overweight before pregnancy (RR 0.32; 95% CI: 0.16, 0.64). The restricted cubic splines model showed an inverted J-shaped relationship between vitamin D concentrations and GDM risk.

CONCLUSIONS

The risk of GDM was significantly reduced in twin pregnant women with vitamin D concentrations ≥ 30 ng/mL in the second trimester.

TRIAL REGISTRATION

ChiCTR-OOC-16,008,203. Retrospectively registered on 1 April 2016.

The Role of Lifestyle Interventions in the Prevention and Treatment of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is one of the most common pregnancy-related endocrinopathies, affecting up to 25% of pregnancies globally. GDM increases the risk of perinatal and delivery complications, and the chance of developing type 2 diabetes mellitus and its complications, including cardiovascular diseases. This elevated risk is then passed on to the next generation, creating a cycle of metabolic dysfunction across generations. For many years, GDM preventive measures have had inconsistent results, but recent systematic reviews and meta-analyses have identified promising new preventative routes. This review aims to summarize the evidence investigating the efficacy of lifestyle treatments for the prevention of GDM and to summarize the effects of two lifestyle interventions, including physical activity and dietary interventions. Based on the present research, future studies should be conducted to investigate whether initiating lifestyle interventions during the preconception period is more beneficial in preventing GDM. In addition, research targeting pregnancy should be designed with a personalized approach. Therefore, studies should customize intervention approaches depending on the presence of modifiable and non-modifiable risk factors at the individual level.

Maternal vitamin D status in early pregnancy and its association with gestational diabetes mellitus in Shanghai: a retrospective cohort study

Background

There is growing interest regarding vitamin D and its potential role in gestational diabetes mellitus (GDM). We aimed to assess maternal vitamin D status in early pregnancy and its relationships with the risk of GDM in a Chinese population in Shanghai.

Methods

The retrospective cohort study included a total of 7816 pregnant women who underwent a 75-g oral glucose tolerance test (OGTT) during 24–28 weeks of gestation. Participants’ demographic information including maternal age, prepregnancy body mass index (BMI), gestational age, parity, season of blood collection, serum 25-hydroxy vitamin D [25(OH)D] data and other blood biomarker data at 6 to 14 weeks of gestation were retrospectivly extracted from the medical records in the hospital information system.

Results

In the cohort, the prevalence of GDM was 8.6% and the prevalence of vitamin D deficiency and insufficiency in early pregnancy was 53.1 and 38.5%, respectively. The mean value of the serum 25(OH)D concentration was 19.6±7.5 ng/mL. The restricted cubic splines model showed an inverted J-shaped relationship in which the risk of GDM decreased when the 25(OH)D concentrations were ≥ 20 ng/mL. Logistic model analysis showed that 25(OH)D concentrations ≥ 30 ng/mL significantly decreased the risk of GDM (odds ratio = 0.63, 95% confidence interval: 0.45-0.89; P = 0.010) compared with 25(OH)D concentrations < 20 ng/ml.

Conclusions

In early pregnancy, vitamin D deficiency and insufficiency were very common, and a high level of vitamin D showed protective effects against the incidence risk of GDM.

Vitamin D in gestational diabetes: a broadened frontier

Vitamin D deficiency is very common among women of reproductive age, even during pregnancy. Different studies have yielded vastly different results regarding whether vitamin D deficiency during pregnancy affects the development and progression of gestational diabetes mellitus (GDM), glycemic control in patients with hyperglycemia, and maternal-fetal outcomes. In addition, concerns, such as the mechanisms underlying the effect of vitamin D deficiency on glucose metabolism during pregnancy, efficacy of vitamin D supplementation in reducing the risk of developing GDM, and recommended supplemental dose of vitamin D, are yet to be elucidated. This article reviewed the latest domestic and international studies in this field, with a focus on the relationship between vitamin D deficiency and GDM, their underlying pathophysiological mechanisms, and the role of vitamin D intervention in the prevention and treatment of GDM. We recommend vitamin D supplementation as soon as possible for all pregnant women with vitamin D deficiency, especially those with GDM.

Association of serum vitamin D status with gestational diabetes mellitus and other laboratory parameters in early pregnant women

Background

The association between serum 25-hydroxy vitamin D (25(OH)D) status and gestational diabetes mellitus (GDM) gained attention in recent years, however the conclusion is still controversial due to many interfering factors, such as region of living, environment, lifestyle, and food supplements. Other metabolites (laboratory parameters) are also important in reflecting gestational states. This study aimed to investigate the association of serum 25(OH)D status in early pregnancy with GDM and other laboratory parameters in pregnant women.

Methods

A total of 1516 pregnant women whose blood glucose were normal before pregnancy in the city of Foshan in Guangdong, China were enrolled in this study. GDM was diagnosed between 24 to 28 weeks of pregnancy following the guidelines from the American Diabetes Association. Maternal serum 25(OH)D and other laboratory parameters—including hematology, coagulation, chemistry, and bone density—were measured utilizing various analytical methods in clinical laboratory at gestational weeks 11 to 14.

Results

The average 25(OH)D concentration was 59.1 ± 12.6 nmol/L. None of the study subjects had 25(OH)D < 25 nmol/L; 434 (28.6%) women had 25(OH)D deficiency (< 50 nmol/L), 882 women (58.2%) had 25(OH)D insufficiency (50–74 mmol/L) and 200 women (13.2%) had 25(OH)D sufficiency (≥ 75 nmol/L). There were 264 (17.4%) women diagnosed with GDM. There was not, however, an association between serum 25(OH)D in early pregnancy and GDM. Interestingly, women with more parity and high serum alkaline phosphatase levels had higher serum 25(OH)D levels. There was a possible positive association between serum 25(OH)D and pre-albumin, and a possible negative association between serum 25(OH)D, creatinine, and thrombin time. This study did not find an association between serum 25(OH)D and bone density.

Conclusions

There were no associations between maternal serum 25(OH)D concentration in early pregnancy and the risk of GDM or bone density. There were, however, correlations between serum 25(OH)D and parity, seasoning at sampling, serum alkaline phosphatase, creatinine, pre-albumin, and coagulation factor thrombin time, which need further study to explain their pathophysiology and clinical significance.

The Impact of Nutritional Supplementation During Pregnancy on the Incidence of Gestational Diabetes and Glycaemia Control

The nutritional state before and throughout pregnancy has a critical impact on the women's health and the baby's development and growth. The release of placental hormones during pregnancy induces/ increases maternal insulin resistance and promotes nutrition utilization by the fetus. Gestational Diabetes Mellitus (GDM) is the most common medical complication in pregnancy and is associated with significant maternal and fetal morbidity. Several studies have examined the effect of physical activity, healthy eating, and various food supplements on the risk of developing gestational diabetes (GDM) and related outcomes. Among those, Myo-Inositol supplementation has shown encouraging results in the prevention of GDM. Maternal vitamin D deficiency has been associated with an elevated risk of GDM, and supplementation can improve glucose haemostasis by lowering fasting blood glucose, HbA1c, and serum insulin concentration. Probiotics modulate the gut microbiota leading to an improved glucose and lipid metabolism, which is proposed to reduce the risk of GDM. We aim to review the strength and limitation of the current evidence for using some nutritional supplements either as single agents or in combinations on the risk of developing GDM and on glycaemic control.

Effect of maternal vitamin D status on risk of adverse birth outcomes: a systematic review and dose-response meta-analysis of observational studies

PURPOSE

Accumulating evidence suggests that vitamin D deficiency increases the risk of adverse perinatal outcomes. However, the dose-response relationship between maternal vitamin D status and adverse birth outcomes remains unclear. Focusing on prospective observational studies, we aimed to explore the dose-response relationship of vitamin D status with the risk of low birth weight (LBW), macrosomia (MA), preterm birth (PTB), small for gestational age (SGA), and intrauterine growth restriction (IUGR).

METHODS

Databases including PubMed, Embase, Scopus, and Web of Science were used up to 19 January 2021 to search for observational studies that fulfilled criteria as follows: cohort studies, case-cohort studies, or nested case-control studies. Random-effects models were used to pool relative risks (RRs) and 95% confidence intervals (CIs) in the observational studies.

RESULTS

A total of 72 publications were included in this systematic review and 71 in the meta-analysis. Maternal 25-hydroxyvitamin D (25(OH)D) concentrations were inversely associated with the risk of LBW (RR: 0.65; 95% CI 0.48-0.86), PTB (RR: 0.67; 95% CI 0.57-0.79), and SGA (RR: 0.61; 95% CI 0.49-0.76) in the highest versus lowest meta-analysis, but not associated with MA and IUGR. Linear dose-response analysis showed that each 25 nmol/L increase in 25(OH)D was associated with a 6% and 10% reduction in the risk of PTB (RR: 0.94; 95% CI 0.90-0.98) and SGA (RR: 0.90; 95% CI 0.84-0.97), respectively.

CONCLUSION

Our study suggests that a sufficient vitamin D status during pregnancy is protective against the risk of LBW, PTB, and SGA.

Association between maternal vitamin D levels and risk of adverse pregnancy outcomes: a systematic review and dose-response meta-analysis

Epidemiological studies have investigated the associations between vitamin D and the risk of adverse pregnancy outcomes; however, the results are conflicting and dose-response relationships remain to be confirmed. This study aimed to summarize previous studies on the associations of vitamin D levels with the risk of gestational diabetes mellitus (GDM), pre-eclampsia (PE), gestational hypertension (GH), and caesarean section (C-section), and to clarify the dose-response trends. PubMed, Embase, Scopus, and Web of Science were searched to identify eligible articles. A total of 69 prospective observational studies including cohort studies, case-cohort studies, or nested case-control studies were included in the current systematic review, of which 68 studies were available for meta-analysis. Compared with the lowest level, the highest level of 25(OH)D was significantly associated with a lower risk of GDM (RR: 0.76; 95% CI: 0.66-0.87), PE (RR: 0.74; 95% CI: 0.60-0.90;), and GH (RR: 0.87; 95% CI: 0.79-0.97); however, no significant relationship was found for C-section (RR: 1.00; 95% CI: 0.90-1.12). There was significant between-study heterogeneity for GDM (I² = 69.2%; P_{heterogeneity} < 0.001), PE (I² = 52.0%; P_{heterogeneity} = 0.001), and C-section (I² = 59.1%; P_{heterogeneity} < 0.001), while no heterogeneity was found for GH (I² = 0.0%; P_{heterogeneity} = 0.676). For each 25 nmol L^-1 increase in 25(OH)D, the pooled RR was 0.92 (95% CI: 0.86-0.97) for GDM and 0.89 (95% CI: 0.84-0.94) for PE, respectively. Notably, the dose-response analysis showed a non-linear relationship between maternal 25(OH)D levels and the risk of PE (P_{non-linearity} = 0.009). Our meta-analysis provides further scientific evidence of the inverse association between 25(OH)D levels and the risk of GDM, PE, and GH, which may be useful for the prevention of pregnancy complications. However, more evidence from prospective studies is needed regarding the dietary intake of vitamin D during pregnancy.

Systematic review and meta-analysis of vitamin D deficiency in different pregnancy on preterm birth: Deficiency in middle pregnancy might be at risk

BACKGROUND

Current studies suggest that vitamin D deficiency during pregnancy can produce a certain effect for preterm birth (PTB), but there is no research showing whether vitamin D deficiency has a consistent effect in different pregnancies; thus, we conducted a systematic review and meta-analysis of 24 observational studies, grouping them according to the gestational age at the time of serum sampling, to investigate whether vitamin D deficiency in different periods of gestation has different effects on PTB and to provide an evidence-based basis for pregnant women to measure and supplement vitamin D.

METHODS

The databases PubMed-Medline, EMBASE, the Cochrane Library, Web of Science, EBSCO, CBM, and CNKI were searched until February 2020. Two researchers independently assessed the eligibility and quality of studies, and STATA 12.0 software was used for meta-analysis.

RESULT

Seven cohort studies, 13 case-control studies, and 4 cross-sectional studies were included from 2500 articles by inclusion and exclusion criteria. After adjusting for age, race, and other confounding factors, meta-analysis results showed that vitamin D deficiency in the first trimester, the second trimester, and the third trimester did not increase the risk of PTB (odds ratio (OR) = 1.01, 95% confidence interval (CI) (0.88, 1.16), P = .867; OR = 1.12, 95%CI (0.92, 1.37), P = .249; OR = 1.05, 95%CI (0.87, 1.27), P = .602). However, there was moderate heterogeneity in the study of vitamin D deficiency in the second trimester, and subgroup analysis suggested that vitamin D deficiency in the second trimester may increase the risk of PTB (OR = 1.33, 95%CI (1.15, 1.54), P = .000). A sensitivity analysis of the second trimester showed that excluding any 1 study did not significantly change the results.

CONCLUSIONS

Vitamin D deficiency in early and late pregnancy may not be associated with PTB, while vitamin D deficiency in middle pregnancy is likely to have an important effect on PTB. Vitamin D levels should be measured in the second trimester of pregnancy, and vitamin D supplements should be provided if necessary.

Maternal diet and offspring telomere length: a systematic review

CONTEXT

Many studies assert a negative influence of inappropriate maternal diet and nutritional status during pregnancy on offspring, not only in utero but throughout life, because of the role in the programing of noncommunicable diseases. Telomere length is a biomarker of aging, and shorter telomeres are associated with chronic disease later in life. Maternal nutrition and nutritional status may be an important determinant of offspring telomere length.

OBJECTIVE

A systematic review was conducted to determine the effect of maternal nutrition and nutritional status in pregnancy on offspring telomere length.

DATA SOURCES

This systematic review was conducted according to PRISMA guidelines. Database searches of PubMed, CINAHL, Scopus, Medline, and Web of Science were performed.

STUDY SELECTION

Included studies assessed the association between maternal nutrition (dietary intake and nutritional status) during pregnancy and offspring telomere length measured in cord blood, serum, plasma, and peripheral blood mononuclear cells.

DATA EXTRACTION

Three authors screened and determined the quality of the articles; disagreements were resolved by a fourth author. All authors compared the compiled data.

RESULTS

Seven studies were extracted and evaluated. Studies comprised a double-blind placebo-controlled trial (n = 1), prospective cohort studies (n = 5), and a cross-sectional study (n = 1). Higher circulating maternal folate and 25-hydroxyvitamin D3 concentrations, along with higher maternal dietary caffeine intakes, were associated with longer offspring telomere length, whereas higher dietary intake of carbohydrate, folate, n-3 polyunsaturated fatty acids, vitamin C, or sodium was not.

CONCLUSION

The limited but suggestive evidence highlights the need for further research to be conducted in this area, particularly longitudinal studies involving larger cohorts of pregnant women.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42019136506.

Maternal vitamin D status and risk of gestational diabetes mellitus: A systematic review and meta-analysis of prospective cohort studies

BACKGROUND

No earlier systematic review and meta-analysis have been done on the association between maternal serum vitamin D status and risk of GDM among prospective studies. The current study was done to systematically review prospective cohort studies (with several years of follow-up) on the association between maternal serum vitamin D deficiency or insufficiency and risk of GDM.

METHODS

Relevant papers published up to January 2020 were searched through PubMed, MEDLINE, SCOPUS, EMBASE, and Google Scholar using suitable keywords. All prospective cohort studies reporting Hazard Ratios (HRs) or Relative Risks (RRs) and 95% Confidence Intervals (CI) for GDM across categories of maternal serum vitamin D status were included.

RESULTS

A total of 29 prospective and nested case-control studies were included in the current systematic review, of which 27 studies had sufficient data for the meta-analysis. Individuals with vitamin D deficiency had a 26% greater risk of developing GDM than those with normal serum vitamin D concentrations (OR: 1.26; 95% CI: 1.13, 1.41). In addition, a significant positive association was seen between combined vitamin D insufficiency and deficiency and risk of developing GDM (OR: 1.23; 95% CI: 1.11, 1.35). Dose-response analysis showed a significant U-shaped non-linear association between serum vitamin D concentrations and risk of developing GDM (P < 0.001), such that those with serum vitamin D concentrations between 40 and 90 nmol/L had significantly reduced risk of GDM.

CONCLUSIONS

We found a significant association between vitamin D deficiency and an increased risk of GDM. The lowest risk of GDM was found among those with a serum vitamin D levels of 40-90 nmol/L. Further studies, including randomized clinical trials, are needed to confirm our findings.

REGISTRATION

PROSPERO (ID: 180722), https://www.crd.york.ac.uk/prospero/.

Effect of Selenium and Iodine on Oxidative Stress in the First Trimester Human Placenta Explants

Imbalanced maternal micronutrient status, poor placentation, and oxidative stress are associated with greater risk of pregnancy complications, which impact mother and offspring health. As selenium, iodine, and copper are essential micronutrients with key roles in antioxidant systems, this study investigated their potential protective effects on placenta against oxidative stress. First trimester human placenta explants were treated with different concentrations of selenium (sodium selenite), iodine (potassium iodide), their combination or copper (copper (II) sulfate). The concentrations represented deficient, physiological, or super physiological levels. Oxidative stress was induced by menadione or antimycin. Placenta explants were collected, fixed, processed, and embedded for laser ablation inductively coupled plasma-mass spectrometry (LA ICP-MS) element imaging or immunohistochemical labelling. LA ICP-MS showed that placenta could uptake selenium and copper from the media. Sodium selenite and potassium iodide reduced DNA damage and apoptosis (p < 0.05). Following oxidative stress induction, a higher concentration of sodium selenite (1.6 µM) was needed to reduce DNA damage and apoptosis while both concentrations of potassium iodide (0.5 and 1 µM) were protective (p < 0.05). A high concentration of copper (40 µM) increased apoptosis and DNA damage but this effect was no longer significant after induction of oxidative stress. Micronutrients supplementation can increase their content within the placenta and an optimal maternal micronutrient level is essential for placenta health.

Maternal Vitamin D Levels During Pregnancy in Association With Autism Spectrum Disorders (ASD) or Intellectual Disability (ID) in Offspring; Exploring Non-linear Patterns and Demographic Sub-groups

Increasing vitamin D deficiency and evidence for vitamin D's role in brain and immune function have recently led to studies of neurodevelopment; however, few are specific to autism spectrum disorder (ASD) and vitamin D in pregnancy, a likely susceptibility period. We examined this in a case-control study of 2000-2003 Southern Californian births; ASD and intellectual disability (ID) were identified through the Department of Developmental Services and controls from birth certificates (N = 534, 181, and 421, respectively, in this analysis). Total 25-Hydroxyvitamin D (25(OH)D) was measured in mid-pregnancy serum, categorized as deficient (<50 nmol/L), insufficient (50-74 nmol/L), or sufficient (≥75 nmol/L, referent category), and examined continuously (per 25 nmol/L). Crude and adjusted odds ratios (AORs) and 95% confidence intervals (95% CI) were calculated. Non-linearity was examined with cubic splines. AORs (95% CI) for ASD were 0.79 (0.49-1.3) for maternal deficiency (9.5%), 0.93 (0.68-1.3) for insufficiency (25.6%), and 0.95 (0.86, 1.05) for linear continuous 25(OH)D. Results were similarly null for ASD with or without ID, and ID only. Interactions were observed; non-Hispanic whites (NHW) (AOR = 0.82, 95% CI = 0.69-0.98) and males (AOR = 0.89, 95% CI = 0.80-0.99) had protective associations for ASD with continuous 25(OH)D. A positive association with ASD was observed in females (AOR = 1.40, 95% CI = 1.06-1.85). With splines, a non-linear inverted j-shaped pattern was seen overall (P = 0.009 for non-linearity), with the peak around 100 nmol/L; a non-linear pattern was not observed among NHW, females, nor for ID. Our findings from a large study of ASD and prenatal vitamin D levels indicate that further research is needed to investigate non-linear patterns and potentially vulnerable sub-groups. LAY SUMMARY: We studied whether mothers' vitamin D levels during pregnancy were related to their children having autism (or low IQ) later. Low vitamin D levels were not related to greater risk of autism or low IQ in children overall. With higher levels of mothers' vitamin D, risk of autism went down in boys, but went up in girls. Risk of autism also went down in children of non-Hispanic white mothers with higher vitamin D levels, but we did not find a relation in other race/ethnic groups.

Influence of vitamin D binding protein polymorphism, demographics and lifestyle factors on vitamin D status of healthy Malaysian pregnant women

BACKGROUND

Vitamin D deficiency (VDD) has been related to vitamin D binding protein (GC) gene polymorphism, demographics and lifestyle factors in different populations. However, previous studies only focused on demographic and lifestyle factors or genetic factors alone. Therefore, this cross-sectional study aimed to assess the association between GC gene polymorphism, demographics and lifestyle factors with VDD among Malaysian pregnant women.

METHOD

Information on demographic characteristics, dietary vitamin D intake from supplement and food, time spent outdoors, skin type and clothing were collected using a questionnaire. Plasma total 25-hydroxyvitamin D (25OHD) levels were measured using an Ultra-High-Performance Liquid Chromatography (UHPLC). Maternal GC single nucleotide polymorphisms (SNPs) (rs4588 and rs7041) were determined using restriction fragment length polymorphism (RFLP) technique.

RESULTS

Results showed that 50.2% of pregnant women were vitamin D deficient (25OHD < 30 nmol/L). VDD (25OHD < 30 nmol/L) was significantly associated with age, veiled clothing, maternal vitamin D intakes from both food and supplements, and GC rs7041(and GC diplotypes). In contrast to previous studies that reported for non-pregnant population, a significant positive association was found between CC genotype for SNP GC rs7041, GC 1s-1s and GC If-2 with risk of VDD (25OHD < 30 nmol/L).

CONCLUSIONS

The high prevalence of maternal VDD found in this study suggests the need for urgent development and implementation of vitamin D supplementation or fortification strategies to reduce VDD among pregnant women. The discrepancy in the association between GC rs7041 gene polymorphism and VDD reflects the variation in the factors associated with VDD in pregnancy compared to non-pregnant state.

Vitamin D and the risk of dystocia: A case-control study

BACKGROUND

Dystocia is one of the most common causes of cesarean section in nulliparous women. Studies have described the presence of vitamin D receptors in the myometrium, but it is still unclear whether vitamin D affects the contractility of the smooth muscles. We therefore aimed to determine the association between the vitamin D serum level at labor and the risk of dystocia.

METHOD

We conducted a case-control study between January 2012 and June 2017. Cases were primiparous women, with spontaneous onset of labor, who gave birth by cesarean section due to dystocia. Controls were primiparous women with a spontaneous vaginal delivery. We included 60 women (30 cases and 30 controls) in the analysis. The differences between cases and controls were assessed using chi-squared test for categorical variables and two-sample t-test or unequal t-test for continuous variables, as appropriate, after evaluation of whether they followed the normal distributions.

RESULTS

The mean serum 25-hydroxyvitamin D concentrations were 53.1nmol/l (95%CI; 45.2 to 60.9) among cases and 69.9nmol/l (95%CI; 57.5 to 82.4) among controls (P = 0.02). The mean plasma parathyroid hormone levels were 2.25 pmol/l and 2.38, respectively (P = 0.57). Even though 78% of all women reported taking a minimum of 10μg/day of vitamin D throughout pregnancy, 43% had vitamin D insufficiency, defined as serum 25-hydroxyvitamin D levels below 50nmol/l.

CONCLUSIONS

In a Danish group of women having a cesarean section due to dystocia, we found decreased vitamin D levels.

Circulating vitamin D and the risk of gestational diabetes: a systematic review and dose-response meta-analysis

PURPOSE

Several meta-analyses of observational studies revealed a modest increase in the risk of gestational diabetes (GDM) among pregnant women with low levels of serum vitamin D. However, no study examined a dose-response meta-analysis as well as a high versus low analysis in this regard.

METHODS

We systematically searched PubMed, Embase, ISI Web of Science, and Scopus up to August 2019 to find prospective observational studies investigating the association of serum 25(OH)D with the risk of developing GDM. Using a random-effects model, the reported risk estimates were pooled.

RESULTS

Nine cohort studies and six nested case-control studies were included in the final analysis (40,788 participants and 1848 cases). Considering linear analysis, each 10 nmol/L increase in circulating 25(OH)D was associated with a 2% lower risk of GDM (effect size (ES): 0.98; 95% CI: 0.98, 0.99; I² = 85.0%, P < 0.001). highest compared with the lowest category of circulating 25(OH)D was associated with a 29% lower risk of GDM, with low evidence of heterogeneity (I² = 45.0%, P = 0.079).

CONCLUSIONS

In conclusion, lower levels of serum 25(OH)D were associated with a higher chance of GDM. Differential results existed between the overall and subgroup analysis, either based on vitamin D detection methods or based on maternal age, although these subgroups partially lowered the heterogeneity.

Serum 25 hydroxyvitamin D levels and affecting factors among preconception fertile women

Background

Recent study found that vitamin D before conception was considered as a potential additional determinant for achieving pregnancy and live births. The study aimed to evaluate the serum 25 hydroxyvitamin D (25(OH)D) levels and its affecting factors among preconception fertile women.

Methods

This cross-sectional study enrolled 410 women aged 22–44 years who attended a preconception genetic counseling clinic from January 2018 to May 2019. Sociodemographic characteristics and reproductive history of women were collected, and height and weight were measured. Serum 25(OH)D concentration was assayed with chemiluminescence immunoassay. Descriptive statistics were used to examine serum 25(OH)D concentration, and socio-demographic characteristics and reproductive history among preconception women. Determinants of vitamin D deficiency and its affecting factors were assessed using χ2 test and logistic regression.

Results

Findings showed 84.4% of women had serum 25(OH)D concentration below 20 ng/mL. Women working indoors as well as without a history of childbirth had significantly lower 25(OH)D levels compared with those non-working individuals and having delivered a previous child (both P < 0.05). The 25(OH)D levels were the lowest in winter among that in spring, summer, and autumn (all P < 0.001). Women in winter have significantly elevated OR of 5.00 (95%CI 1.75–14.25) to develop vitamin D deficiency. Seasonal variation in serum 25(OH)D levels was not present in non-working individuals and women aged 31–44 years.

Conclusions

Vitamin D deficiency is common among preconception women especially nulliparous women and working women, which propose to screen serum 25(OH)D on preconception evaluation and emphasize need vitamin D supplements and get sunshine exposure.

Newborn vitamin D levels in relation to autism spectrum disorders and intellectual disability: A case-control study in california

Vitamin D deficiency has been increasing concurrently with prevalence of autism spectrum disorders (ASD), and emerging evidence suggests vitamin D is involved in brain development. Most prior studies of ASD examined vitamin D levels in children already diagnosed, but a few examined levels during perinatal development, the more likely susceptibility period. Therefore, we examined newborn vitamin D levels in a case-control study conducted among births in 2000-2003 in southern California. Children with ASD (N = 563) or intellectual disability (ID) (N = 190) were identified from the Department of Developmental Services and compared to population controls (N = 436) identified from birth certificates. 25-hydroxyvitamin D (25(OH)D) was measured in archived newborn dried blood spots by a sensitive assay and corrected to sera equivalents. We categorized 25(OH) D levels as deficient (<50 nmol/L), insufficient (50-74 nmol/L), and sufficient (≥75 nmol/L), and also examined continuous levels, using logistic regression. The adjusted odds ratios (AOR) and 95% confidence intervals for ASD were 0.96 (0.64-1.4) for 25(OH)D deficiency (14% of newborns) and 1.2 (0.86-1.6) for insufficiency (26% of newborns). The AORs for continuous 25(OH)D (per 25 nmol/L) were 1.0 (0.91-1.09) for ASD and 1.14 (1.0-1.30) for ID. Thus, in this relatively large study of measured newborn vitamin D levels, our results do not support the hypothesis of lower 25(OH)D being associated with higher risk of ASD (or ID), although we observed suggestion of interactions with sex and race/ethnicity. 25(OH)D levels were relatively high (median 84 nmol/L in controls), so results may differ in populations with higher prevalence of low vitamin D levels. Autism Res 2019, 12: 989-998. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We studied whether vitamin D levels measured at birth were related to whether a child later developed autism (or low IQ). Our results did not show that children with autism, or low IQ, overall had lower vitamin D levels at birth than children without autism. Vitamin D levels were fairly high, on average, in these children born in Southern California.