Maternal vitamin D deficiency, ethnicity and gestational diabetes

Vitamin D supplementation for women during pregnancy

BACKGROUND

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

OBJECTIVES

To examine whether vitamin D supplementation alone or in combination with calcium or other vitamins and minerals given to women during pregnancy can safely improve certain maternal and neonatal outcomes.

SEARCH METHODS

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

SELECTION CRITERIA

Randomised and quasi-randomised trials evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy in comparison to placebo or no intervention.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Vitamin D supplementation modulates glycated hemoglobin (HBA1c) in diabetes mellitus

Diabetes is a metabolic illness that increases protein glycosylation in hyperglycemic conditions, which can have an impact on almost every organ system in the body. The role of vitamin D in the etiology of diabetes under RAGE (receptor for advanced glycation end products) stress has recently received some attention on a global scale. Vitamin D's other skeletal benefits have generated a great deal of research. Vitamin D's function in the development of type 1 and type 2 diabetes is supported by the discovery of 1,25 (OH)2D3 and 1-Alpha-Hydroylase expression in immune cells, pancreatic beta cells, and several other organs besides the bone system. A lower HBA1c level, metabolic syndrome, and diabetes mellitus all seems to be associated with vitamin D insufficiency. Most of the cross-sectional and prospective observational studies that were used to gather human evidence revealed an inverse relationship between vitamin D level and the prevalence or incidence of elevated HBA1c in type 2 diabetes. Several trials have reported on the impact of vitamin D supplementation for glycemia or incidence of type 2 diabetes, with varying degrees of success. The current paper examines the available data for a relationship between vitamin D supplementation and HBA1c level in diabetes and discusses the biological plausibility of such a relationship.

The Degree of Prepregnancy Vitamin D Deficiency Is Not Associated With Gestational Diabetes in Women Undergoing ART

Context

Gestational diabetes mellitus (GDM) is a common pregnancy complication, particularly in women undergoing assisted reproductive technology (ART). An association of GDM with vitamin D in women conceiving naturally has been described; however, studies have yielded heterogeneous results.

Objective

To analyze the association between prepregnancy total and free vitamin D and GDM incidence in women undergoing ART.

Methods

Post hoc analysis of a prospective study at the Reproductive and Genetic Hospital of CITIC-Xiangya in Changsha, China. Total and free vitamin D were measured 1 day before embryo transfer. The patients were screened for GDM using the oral glucose tolerance test.

Results

A total of 1593 women were included in the study, among whom 256 (16.1%) developed GDM. According to international guidelines for total 25-hydroxyvitamin D [25(OH)D], 47 (2.9%) patients had sufficient (≥30 ng/mL) levels, while 696 (43.7%) were insufficient (20 to <30 ng/mL) and 850 (54.4%) were deficient (<20 ng/mL). Comparing GDM and non-GDM patients, there was no significant difference in total nor free vitamin D levels (P = .340 and .849). Similarly, analysis of GDM rates by quintiles of total and free 25(OH)D showed no significant association in one-way ANOVA (P = .831 and .799). Multivariate logistic regression, considering age, BMI, and fasting glucose, also did not show a significant influence of the 2 vitamin D forms on GDM incidence (P = .266 and .123 respectively).

Conclusion

In this relatively vitamin D deficient/insufficient ART cohort, the degree of neither total nor free vitamin D deficiency before pregnancy was associated with the occurrence of GDM.

The germicidal effect, biosafety and mechanical properties of antibacterial resin composite in cavity filling

In recent years, dental resin materials have become increasingly popular for cavity filling. However, these materials can shrink during polymerization, leading to microleakages that enable bacteria to erode tooth tissue and cause secondary caries. As a result, there is great clinical demand for the development of antibacterial resins. The principle of antibacterial resin includes contact killing and filler-release killing of bacteria. For contact killing, quaternary ammonium salts (QACs) and antibacterial peptides (AMPs) can be added. For filler-release killing, chlorhexidine (CHX) and nanoparticles are used. These antibacterial agents are effective against gram-positive bacteria, gram-negative bacteria, fungi, and more. Among them, QACs has a lasting antibacterial effect, and silver nanoparticles even have a certain ability to kill viruses. Biocompatibility-wise, QACs, AMPs, and CHX have low cytotoxicity to cells when added into the resin. However, nanoparticles with smaller particle sizes have higher cytotoxicity. In terms of mechanical properties, QACs, AMPs, and CHX do not negatively affect the resin. However, the addition of magnesium oxide can have a negative impact. This paper reviews the types and antibacterial principles of commonly used antibacterial resins in recent years, evaluates their antibacterial effect, biological safety, and mechanical properties, and provides references for selecting clinical filling materials.

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.

Carbohydrate content of human milk is affected by seasonal variations: a retrospective observational study

OBJECTIVE

The influence of seasonal variation upon human milk macronutrient content has not been elucidated. This study aimed to compare the macronutrient content of HM produced by lactating mothers during the winter and the summer seasons.

STUDY DESIGN

Macronutrient content of colostrum milk samples collected from lactating mothers of healthy term infants between March 2012 and February 2016 was measured by mid-infrared spectroscopy and compared.

RESULT

The carbohydrate content of the colostrum was significantly higher in the summer season than in the winter season (6.2 ± 1.3 vs. 5.5 ± 1.4, p-value < 0.001). Protein, fat, and energy contents were similar in summer and winter in both groups (protein 2.7 ± 2.1 vs. 2.6 ± 2.2 g/100 ml, fat 2.6 ± 1.9 vs. 2.35 ± 1.9 g/100 ml, and energy 62 ± 19.1 vs. 60.5 ± 21 kcal/100 ml, respectively).

CONCLUSION

The carbohydrate content in colostrum obtained from mothers of term infants was affected by seasonal variations.

Early pregnancy vitamin D insufficiency and gestational diabetes mellitus

OBJECTIVES

To test the hypothesis that a link existed between vitamin D levels in the first trimester and gestational diabetes mellitus (GDM).

METHODS

The 25-hydroxyvitamin D₃ levels were tested in the first trimester and pregnant outcomes were followed up in 1726 women.

RESULTS

Only 5.9% of pregnant women have sufficient 25(OH)D₃ . More women with GDM are in the status of 25(OH)D₃ insufficiency than women with normal glucose tolerance (NGT) (p < 0.05). Age (odds ratio [OR]: 1.047, 95% confidence interval [CI]: 1.014-1.081), pre-pregnancy body mass index (BMI) (OR: 1.132, 95%CI: 1.092-1.173) were risk factors of GDM while 25-(OH) D₃ (OR: 0.979, 95%CI: 0.960-0.999) was a protective factor. After adjusted for maternal age and pre-pregnancy BMI, 25(OH)D₃ insufficiency (<30 ng/mL) is an independent predictor of GDM (OR: 2.122, 95%CI: 1.084-4.155); 25(OH)D₃ level correlated with fasting blood glucose in the first trimester negatively.

CONCLUSION

Vitamin D insufficiency in early pregnancy was significantly associated with an increased risk for GDM in Chinese women.

Vitamin D Status and Gestational Diabetes in Russian Pregnant Women in the Period between 2012 and 2021: A Nested Case-Control Study

Several meta-analyses found an association between low maternal serum 25-hydroxyvitamin D (25(OH)D) level and gestational diabetes mellitus (GDM). However, some of them reported significant heterogeneity. We examined the association of serum 25(OH)D concentration measured in the first and in the second halves of pregnancy with the development of GDM in Russian women surveyed in the periods of 2012−2014 and 2018−2021. We conducted a case−control study (including 318 pregnant women) nested on two previous studies. In 2012−2014, a total of 214 women (83 GDM and 131 controls) were enrolled before 15 weeks of gestation and maternal serum 25(OH)D concentrations were measured twice: at 8th−14th week of gestation and simultaneously with two-hour 75 g oral glucose tolerance test (OGTT) at 24th−32nd week of gestation. In the period of 2018−2021, 104 women (56 GDM and 48 controls) were included after OGTT and 25(OH)D concentrations were measured at 24th−32nd week of gestation. Median 25(OH)D levels were 20.0 [15.1−25.7] vs. 20.5 [14.5−27.5] ng/mL (p = 0.565) in GDM and control group in the first half of pregnancy and 25.3 [19.8−33.0] vs. 26.7 [20.8−36.8] ng/mL (p = 0.471) in the second half of pregnancy, respectively. The prevalence rates for vitamin D deficiency (25(OH)D levels < 20 ng/mL) were 49.4% and 45.8% (p = 0.608) in the first half of pregnancy and 26.2% vs. 22.1% (p = 0.516) in the second half of pregnancy in women who developed GDM and in women without GDM, respectively. The frequency of vitamin D supplements intake during pregnancy increased in 2018−2021 compared to 2012−2014 (p = 0.001). However, the third trimester 25(OH)D levels and prevalence of vitamin D deficiency (25.5 vs. 23.1, p = 0.744) did not differ in women examined in the periods of 2012−2014 and 2018−2021. To conclude, there was no association between gestational diabetes risk and maternal 25(OH)D measured both in the first and in the second halves of pregnancy. The increased prevalence of vitamin D supplements intake during pregnancy by 2018−2021 did not lead to higher levels of 25(OH)D.

Vitamin D supplementation higher than 2000 IU/day compared to lower dose on maternal–fetal outcome: Systematic review and meta-analysis

Introduction:

Although vitamin D is widely known as an essential micronutrient during pregnancy, the exact supplementation dose to prevent maternal–fetal outcomes remains a question. This study aims to provide a systematic review and a meta-analysis of data from randomized controlled trial on > 2000 IU/day vitamin D supplementation compared to ⩽ 2000 IU/day; and ⩽ 2000 IU/day compared to placebo, on their effects on the incidence of preeclampsia, gestational diabetes mellitus, preterm birth, and differences on birth weight.

Methods:

A systematic literature search on PubMed, EBSCO-MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases was carried out to evaluate randomized controlled trial studies on the effects of oral vitamin D > 2000 IU/day versus ⩽ 2000 IU/day; and ⩽ 2000 IU/day versus placebo, on preeclampsia, gestational diabetes mellitus, preterm birth and birth weight. Risk ratio, mean difference, and 95% confidence interval were calculated.

Results:

There were a total of 27 randomized controlled trials selected. Maternal vitamin D supplementation > 2000 IU/day had a positive effect only on gestational diabetes mellitus (seven randomized controlled trials; risk ratio = 0.70, 95% confidence interval: 0.51–0.95, I2 = 0). Vitamin D supplementation ⩽ 2000 IU/day has reduced the risk of preeclampsia (three randomized controlled trials; risk ratio = 0.29, 95% confidence interval: 0.09–0.95, I2 = 0), with no significant difference when compared to > 2000 IU/day (eight randomized controlled trials; risk ratio = 0.80, 95% confidence interval: 0.51–1.24, I2 = 31). No difference in preterm birth risk and birth weight after vitamin D supplementation. The quality of evidence varies from moderate to very low certainty. The risk of preeclampsia and gestational diabetes mellitus after high-dose versus low-dose vitamin D supplementation was the ones with moderate certainty.

Conclusion:

Vitamin D supplementation > 2000 IU/day might be important to reduce the risk of gestational diabetes mellitus. Lower dose vitamin D supplementation (⩽ 2000 IU/day) seemed adequate to reduce the risk of preeclampsia, with no significant difference compared to the higher dose.

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.

A case-control study to predict the risk of gestational diabetes mellitus by initial fasting blood sugar or past gestational history

BACKGROUND

Gestational diabetes mellitus (GDM) deserves proper prevention, diagnosis, and management due to healthcare implications from both maternal and fetal concerns.

OBJECTIVE

To evaluate the rate and investigate the risk factors for developing GDM.

MATERIALS AND METHODS

In this case-control, universal screening for GDM between 24 and 28 wk of gestation was performed in 613 pregnant women attending a prenatal clinic in Tehran who were followed-up until delivery between March 2017 to March 2018. Of the 613 women, 143 had GDM and 470 had normal glucose tolerance test as the primary diagnosis. Some GDM risk factors were compared in two groups.

RESULTS

Impaired glucose tolerance test was detected in 143 (23.3%) patients. Prevalence of GDM was higher in the first-trimester fasting blood sugar (FBS) > 90 qmg/dl group (p < 0.001). Comparison of the GDM and the normal glucose tolerance test groups demonstrated significant differences in maternal age, first-trimester FBS, third-trimester vitamin D level, maternal platelet count, maternal body mass index (BMI) (before 12 wk of gestation), weight gain during pregnancy, and the history of gestational complications in previous pregnancy (p < 0.01). In logistic regression, GDM was independently associated with older maternal age, higher first-trimester FBS, the history of gestational complications in previous pregnancy, lower third-trimester vitamin D level, and higher maternal platelet count (p < 0.01).

CONCLUSION

Both patients with higher initial FBS and the history of gestational complications in previous pregnancy should be considered high risk for GDM and screened earlier.

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.

Prevention and Management of Gestational Diabetes Using Vitamin D Supplementation: An Overview and Appraisal of Clinical Trials

A number of studies have examined the role of vitamin D in reproductive processes and disorders of pregnancy such as gestational diabetes mellitus (GDM). Although observational studies have linked maternal vitamin D deficiency with a plethora of adverse pregnancy outcomes including GDM, intervention trials generally do not support the use of vitamin D supplementation for GDM prevention or management. This narrative review provides an up-to-date overview and critical appraisal of randomised controlled trials (RCTs) to describe the current state of knowledge regarding the efficacy of vitamin D supplementation for preventing and/or managing GDM. Overall, although RCT data indicates a potential benefit of vitamin D in maternal glycaemic control, results are highly disparate and the data published to date have not conclusively established the efficacy of vitamin D in GDM prevention. There are, however, several limitations within the existing literature, including some considerable challenges that are unique to vitamin D trials, which should be carefully considered in the interpretation of the evidence and design of future studies. For now, many unanswered questions remain, and there is still a need for adequately powered and well-designed trials before routine supplementation can be recommended in the context of GDM.

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 Vitamin D levels and gestational diabetes mellitus: analysis of early pregnancy cohort from a teaching hospital of Kashmir Valley

Background and Aims:

The association of gestational diabetes mellitus and serum Vitamin D levels in different trimesters of pregnancy has been studied recently. We conducted this study in an prospective observational cohort of well-characterized healthy pregnant women to examine the relationship between 1^st trimester Vitamin D levels and Gestational Diabetes Mellitus (GDM) status during pregnancy.

Methods:

All pregnant women attending the out-patient department of Gynecology & Obstetrics, aged less than 35 years, and who were in their first trimester were included in the study. Socio-demographic, anthropometric details, clinical details, food frequency questionnaire and physical activity data was collected using validated pretested questionnaire.

Results:

The comparison between those with GDM and those with normal glucose levels has been illustrated. Women in the GDM are older than those in the non-GDM group. The women in GDM group were taller, heavier and their BMI was greater than those in the non-GDM group. There were no significant differences in dietary intake at baseline between mothers with GDM and those with normal glucose levels. Further, it was found that Vitamin D concentration of <30 nmol/L was found among higher among those with GDM and the relationship was statistically significant.

Conclusion:

There is an association between maternal Vitamin D deficiency and increased risk for GDM in early pregnancy among Kashmiri women.

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.

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.

Vitamin D, and Maternal and Child Health

Vitamin D has important roles in calcium metabolism and in the prevention of rickets and osteomalacia; low levels of 25-hydroxyvitamin D are common in the general population and amongst pregnant women. Whilst there is a wealth of observational evidence linking vitamin D deficiency to a wide range of disease outcomes, there are currently few high-quality randomised controlled trials to confirm any causal associations, although many are currently in progress. Furthermore, currently, the vast majority of published guidelines recommend standard supplemental vitamin D doses for children and pregnant women, yet there is increasing recognition that individual characteristics and genetic factors may influence the response to supplementation. As such, future research needs to concentrate on documenting definite beneficial clinical outcomes of vitamin D supplementation, and establishing personalised dosing schedules and demonstrating effective approaches to optimising initiation and adherence.

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.

The relationship between maternal vitamin D status during third trimester of pregnancy and maternal and neonatal outcomes: A longitudinal study

Background

Vitamin D deficiency is a common nutritional concern and leads to several problems among some population groups.

Objective

The aim of the current study was to evaluate the relationship between maternal vitamin D status and gestational weight gain, maternal biochemical parameters, mode of delivery, and infants' growth indices at birth.

Materials and Methods

A longitudinal study between March and June 2017 was carried on 82 mothers in Ahvaz. Blood samples of each mother were obtained at the mean of the third trimester to assay lipid indices (total cholesterol, triglycerides, low-density lipoprotein, and high-density lipoprotein cholesterol), fasting blood sugar, and 25-hydroxy vitamin D. Anthropometric assessment of newborns was recorded from neonatal health card at birth.

Results

Mean maternal 25-hydroxy vitamin D level was 22.52 nmol/L; 7.33% of mothers had vitamin D deficiency, 76.6% had vitamin D insufficiency, and 15.9% were normal. The mean neonate birth weight, length, and head circumference of mothers who were on the third tercile of 25-hydroxy vitamin D serum level was significantly higher than those in the first tercile (p < 0.001, p = 0.004 and p < 0.001, respectively). Maternal vitamin D serum level had an adverse relationship with fasting blood sugar.

Conclusion

Low levels of serum vitamin D may cause adverse pregnancy outcomes and delivery of infants with insufficient growth at birth.

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.

The DALI vitamin D randomized controlled trial for gestational diabetes mellitus prevention: No major benefit shown besides vitamin D sufficiency

BACKGROUND & AIMS

As vitamin D deficiency is associated with an increased risk of gestational diabetes mellitus (GDM), we aimed to test vitamin D supplementation as a strategy to reduce GDM risk (evaluated after fasting plasma glucose (FPG), insulin resistance and weight gain) in pregnant overweight/obese women.

METHODS

The DALI vitamin D multicenter study enrolled women with prepregnancy body mass index (BMI) ≥ 29 kg/m², ≤19 + 6 weeks of gestation and without GDM. Participants were randomized to receive 1600 IU/day vitamin D3 or placebo (each with or without lifestyle intervention) on top of (multi)vitamins supplements. Women were assessed for vitamin D status (sufficiency defined as serum 25-hydroxyvitamin D (25(OH)D) ≥ 50 nmol/l), FPG, insulin resistance and weight at baseline, 24-28 and 35-37 weeks. Linear or logistic regression analyses were performed to assess intervention effects.

RESULTS

Average baseline serum 25(OH)D was ≥50 nmol/l across all study sites. In the vitamin D intervention arm (n = 79), 97% of participants achieved target serum vitamin 25(OH)D (≥50 nmol/l) at 24-28 weeks and 98% at 35-37 weeks vs 74% and 78% respectively in the placebo arm (n = 75, p < 0.001). A small but significantly lower FPG (-0.14 mmol/l; CI95 -0.28, -0.00) was observed at 35-37 weeks with the vitamin D intervention without any additional difference in metabolic status, perinatal outcomes or adverse event rates.

CONCLUSION

In the DALI vitamin D trial, supplementation with 1600 IU vitamin D3/day achieved vitamin D sufficiency in virtually all pregnant women and a small effect in FPG at 35-37 weeks. The potential of vitamin D supplementation for GDM prevention in vitamin D sufficient populations appears to be limited.

TRIAL REGISTRATION NUMBER

ISRCTN70595832.

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.

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.

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.

Maternal risk factors and newborn infant vitamin D status: a scoping literature review

Low vitamin D (VitD) status is common among newborn infants, more so in temperate latitudes with evidence that maternal VitD deficiency is a major risk factor given that the neonate relies solely on maternal-fetal transfer of VitD. This scoping review was conducted to provide an overview of the latest evidence from studies regarding the impact of maternal risk factors on infant 25-hydryoxyvitamin D [25(OH)D] concentrations with a focus on studies in Canada and the United States. Several maternal risk factors that contribute to low maternal-fetal 25(OH)D concentrations have been reported over many decades, but no clear pattern has been established for multiethnic populations. For example, darker skin pigmentation and ethnicity are common risk factors for low VitD status. Studies in predominantly white women showed that supplementation of VitD during pregnancy causes significant increases in maternal serum 25(OH)D which often improves cord serum 25(OH)D values. In addition, VitD recommendations by health care professionals and adherence to supplementation by pregnant women appear to positively influence maternal and infant 25(OH)D concentrations. Conversely, winter season, obesity, lower socioeconomic status including lifestyle factors (smoking), and use of medication pose risk for lower maternal-fetal transfer of VitD. However, there is still a dearth of pertinent data on the relationship between some of the maternal risk factors and newborn 25(OH)D concentrations, for instance, relationships between gestational diabetes and neonatal VitD status. Additional research is required to determine if the same target for 25(OH)D concentrations applies for pregnant women, neonates, and infants.

Association of Vitamin D and Parathyroid Hormone with Insulin Sensitivity, Beta Cell Function and Gestational Diabetes in Pregnancy: A Cross-Sectional, Observational Study

INTRODUCTION

Vitamin D (25OHD) and parathyroid hormone (PTH) are associated with dysglycemia, and we investigated them in gestational diabetes mellitus (GDM).

METHODS

In this cross-sectional, observational study, we included 75 pregnant women between 24 and 28 weeks of gestation. A fasting venous sample was collected for plasma glucose (FPG), insulin, PTH and 25OHD. Glucose and insulin samples were collected hourly after 75 g glucose load for 2 h. Insulin sensitivity was estimated by the Matsuda index (MI) and beta cell function by the insulin secretion sensitivity index (ISSI-2). The subjects were stratified into three groups and tertiles according to the 25OHD and PTH, respectively. Appropriate statistical tests were used to compare the MI, ISSI-2 and GDM among the groups.

RESULTS

GDM was seen in 14/75, and of these patients, 2 were 25OHD deficient, 7 insufficient and 5 had sufficient 25OHD. MI and ISSI-2, though not correlated with the 25OHD, decreased from the lower to higher PTH tertile (P < 0.001). FPG, AUCgluc (area under the curve glucose) and prevalence of GDM increased from the lower to higher PTH tertile (P < 0.001).

CONCLUSION

Increased PTH was associated with decreased insulin sensitivity, beta cell function and GDM in pregnancy, irrespective of the underlying 25OHD level.

Vitamin D status by sociodemographic factors and body mass index in Mexican women at reproductive age

OBJECTIVE

To describe the prevalence of Vitamin D deficiency (VDD) and insufficiency (VDI), and the main dietary sources of vitamin D (VD) in a probabilistic sample of Mexican women at reproductive age participating in Ensanut 2012, stratified by sociodemographic factors and body mass index (BMI) categories.

MATERIALS AND METHODS

Serum concentrations of 25-hydroxyvitamin-D(25-OH-D) were determined using an ELISA technique in 4162 women participants of Ensanut 2012 and classified as VDD, VDI or optimal VD status. Sociodemographic, anthropometric and dietary data were also collected. The association between VDD/VDI and sociodemographic and anthropometry factors was assessed adjusting for potential confounders through an estimation of a multinomial logistic regression model.

RESULTS

The prevalence of VDD was 36.8%, and that of VDI was 49.8%. The mean dietary intake of VD was 2.56 μg/d. The relative risk ratio (RRR) of VDD or VDI was calculated by a multinomial logistic regression model in 4162 women. The RRR of VDD or VDI were significantly higher in women with overweight (RRR: 1.85 and 1.44, p<0.05), obesity (RRR: 2.94 and 1.93, p<0.001), urban dwelling (RRR:1.68 and 1.31, p<0.06), belonging to the 3rd tertile of income (RRR: 5.32 and 2.22, p<0.001), or of indigenous ethnicity (RRR: 2.86 and 1.70, p<0.05), respectively.

CONCLUSION

The high prevalence of VDD/VDI in Mexican women calls for stronger actions from the health authorities, strengthtening the actual policy of food supplementation and recommending a reasonable amount of sun exposure.

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

BACKGROUND

Pregnant women are at increased susceptibility to vitamin D deficiency. Hence, there is continuing interest in determining how vitamin D influences pregnancy health. We aimed to compare vitamin D status in two distinct populations of pregnant women in Australia and New Zealand and to investigate the relationship between vitamin D status and pregnancy outcome. This included evaluating possible effect measure modifications according to fetal sex.

METHODS

Serum 25-hydroxy vitamin D (25(OH)D) was measured at 15 ± 1 weeks' gestation in 2800 women from Adelaide and Auckland who participated in the multi-centre, prospective cohort SCreening fOr Pregnancy Endpoints (SCOPE) study.

RESULTS

Mean serum 25(OH)D in all women was 68.1 ± 27.1 nmol/L and 28% (n = 772) were considered vitamin D deficient (< 50 nmol/L). Serum 25(OH)D was lower in the women recruited in Adelaide when compared to the women recruited in Auckland and remained lower after adjusting for covariates including maternal body mass index and socioeconomic index (Adelaide: 58.4 ± 50.3 vs. Auckland: 70.2 ± 54.5 nmol/L, P < 0.001). A 53% decreased risk for gestational diabetes mellitus (GDM) was observed with high (> 81 nmol/L) "standardised" vitamin D status when compared to moderate-high (63-81 nmol/L, aRR, 0.47; 95% CI: 0.23, 0.96). Marginal sex-specific differences occurred between vitamin D status and GDM: women carrying a female fetus had a 56% decreased risk for GDM in those with low-moderate levels of standardised vitamin D (44-63 nmol/L) compared to moderate-high levels (aRR: 0.44; 95% CI: 0.20, 0.97), whilst in women carrying a male fetus, a 55% decreased risk of GDM was found with high standardised vitamin D when compared to moderately-high vitamin D, but this was not statistically significant (aRR: 0.45; 95% CI: 0.15, 1.38).

CONCLUSIONS

High serum 25(OH)D at 15 ± 1 weeks' gestation was shown to be protective against the development of GDM. A possible association between fetal sex, vitamin D status and GDM provides further questions and encourages continual research and discussion into the role of vitamin D in pregnancy, particularly in vitamin D replete populations.

Association between vitamin D status and hyperinsulinism

Aims: Some studies have suggested that vitamin D deficiency is associated with an increased risk of first trimester miscarriages, others have suggested that it is associated with an increased risk of hyperinsulinism/insulin resistance and the development of gestational diabetes. Hyperinsulinism is also thought to increase miscarriages. We investigated the association between vitamin D levels and hyperinsulinism in a cohort of recurrent miscarriage patients. Methods: Patients undergoing miscarriage investigations had insulin and vitamin D levels tested. Vitamin D levels were classified as: sufficient (≥75 nmol/L), insufficient (50-74.9 nmol/L) or deficient (<50 nmol/L). Hyperinsulinism was assessed via a 75 g oral glucose tolerance test (OGTT) with insulin studies. Results: One hundred and fifty-five patients underwent the testing. Hyperinsulinism was detected in 58.3% of the vitamin D deficient group, 38.7% of the insufficient group, and 33.3% of the sufficient group (chi-square p = .034). There were no significant associations between BMI and vitamin D levels, or BMI and hyperinsulinism. Caucasians comprised 82% of the clinic, and 67% of these women had vitamin D insufficiency/deficiency. Noncaucasians comprised 18% of the clinic but 89% of these patients had vitamin D insufficiency/deficiency. Discussion: We found that insufficient or deficient vitamin D levels were significantly associated with hyperinsulinism in these patients. Vitamin D deficiency is also thought to contribute to an increased risk of adverse pregnancy outcomes including preeclampsia, preterm birth, small-for-gestational-age gestational diabetes mellitus, and miscarriages. Larger level one trials are needed to establish if increasing serum vitamin D levels prior to conception or in early pregnancy improves adverse pregnancy outcomes.

Maternal vitamin D supplementation during pregnancy

Introduction

Maternal vitamin D status in pregnancy has been linked to many health outcomes in mother and offspring. A wealth of observational studies have reported on both obstetric outcomes and complications, including pre-eclampsia, gestational diabetes, mode and timing of delivery. Many foetal and childhood outcomes are also linked to vitamin D status, including measures of foetal size, body composition and skeletal mineralization, in addition to later childhood outcomes, such as asthma.

Sources of data

Synthesis of systematic and narrative reviews.

Areas of agreement and controversy

The findings are generally inconsistent in most areas, and, at present, there is a lack of data from high-quality intervention studies to confirm a causal role for vitamin D in these outcomes. In most areas, the evidence tends towards maternal vitamin D being of overall benefit, but often does not reach statistical significance in meta-analyses.

Growing points and areas timely for developing research

The most conclusive evidence is in the role of maternal vitamin D supplementation in the prevention of neonatal hypocalcaemia; as a consequence the UK department of health recommends that pregnant women take 400 IU vitamin D daily. High-quality randomized placebo-controlled trials, such as the UK-based MAVIDOS trial, will inform the potential efficacy and safety of vitamin D supplementation in pregnancy across a variety of outcomes.

Serum 25-hydroxyvitamin D and cardiovascular disease risk factors in women with excessive weight gain during pregnancy and in their offspring at age 5-6 years

BACKGROUND/OBJECTIVE

Low 25-hydroxyvitamin D levels [25(OH)D] may increase the risk for cardiovascular disease (CVD). In pregnant women excessive weight gain and 25(OH)D deficiency are common complications and both could have deleterious consequences on their children. We aimed to study the relationship between serum 25(OH)D and CVD risk factors in pregnant women and in their offspring at school age.

SUBJECTS/METHODS

Fasting serum 25(OH)D and its bioavailable fraction were quantified in 310 healthy pregnant women [with adequate (n = 113), insufficient (n = 113) and excessive (n = 84) weight gain]. A follow-up at 5-6 years was performed in sixty-six children born of these mothers. Lipids, insulin, glucose, and high-sensitivity C-reactive protein (hsCRP) were measured in all subjects. Children's carotid intima-media thickness (cIMT) together with visceral and intra-abdominal fat were measured by ultrasonography.

RESULTS

Lower maternal 25(OH)D concentrations were associated with lower maternal age, and higher body mass index, triglycerides and hsCRP (all p < 0.05). In women with excessive weight gain during gestation, serum 25(OH)D concentrations showed independent associations with maternal hsCRP (β = -0.283 p = 0.03) and triglycerides (β = -0.436, p = 0.005). Maternal serum 25(OH)D concentrations were also independently associated with cIMT (β = -0.288, p = 0.04), visceral fat (β = -0.281, p = 0.01) and intra-abdominal fat (β = -0.248, p = 0.01) in their children at 5-6 years.

CONCLUSIONS

Lower serum 25(OH)D concentrations were related to CVD risk factors in pregnant woman and in their offspring. The cardiometabolic consequences of low 25(OH)D concentrations during pregnancy could be aggravated by excessive weight gain during gestation.

Effects of Vitamin D Deficiency on Incidence Risk of Gestational Diabetes Mellitus: A Systematic Review and Meta-analysis

INTRODUCTION

Proper nutrition is important for overall health, and it reduces healthcare costs associated with malnutrition. Many studies have investigated vitamin D deficiency and its role in gestational diabetes and controversial data have reported. A comprehensive consideration of articles in this field provides the possibility of a general study of this relationship. This meta-analysis is an evaluation of the relationship between vitamin D deficiency and gestational diabetes.

MATERIAL AND METHODS

Different databases (such as PubMed, Science Information Institute, EmBase, Scopus, and the Cochrane Library) were searched for studies and eligible English articles published before February 2017 that have reported the risk of gestational diabetes in relation to vitamin D deficiency. This relationship was measured using odds ratios (ORs) with a confidence interval (CI) of 95%. The influence of each study was measured through sensitivity analysis. Funnel plots, Egger regression tests, and the Begg-Mazumdar correlation test were used to determine bias or publication bias. STATA (version 11.2) was used for all analyses.

RESULTS

Twenty-six studies were selected as eligible for this research and included in the final analysis. In general, vitamin D deficiency among mothers may be related to an increased risk of gestational diabetes (OR = 1.18; 95% CI, 1.01-1.35; p < 0.001). The serum level of 25(OH)D is less meaningful in people with gestational diabetes than in those who have normal glucose tolerance. Subgroup analysis showed that the results concerning this association may vary with study design but do not change with country of origin.

CONCLUSION

Some evidence has shown that vitamin D deficiency may increase the risk of gestational diabetes.

Vitamin D, Gestational Diabetes, and Measures of Glucose Metabolism in a Population-Based Multiethnic Cohort

OBJECTIVE

We explored associations between maternal 25-hydroxyvitamin D (25(OH)D) status during pregnancy and gestational diabetes (GDM) and other measures of glucose metabolism.

METHODS

We analysed 25(OH)D at 15 and 28 gestational weeks (GW) in 745 multiethnic pregnant women attending antenatal care units in Oslo, Norway, between 2008 and 2010. GDM was diagnosed with a 75 g oral glucose tolerance test at 28 GW. Separate regression analyses were performed to investigate associations between 25(OH)D and GDM and measures of glucose metabolism.

RESULTS

A higher proportion of ethnic minority women had GDM (p < 0.01) and low 25(OH)D (p < 0.01) compared to Europeans. In logistic regression analyses, 25(OH)D < 50 nmol/L was associated with GDM after adjusting for age, parity, education, and season (OR 1.6; 95% CI 1.1-2.2). After additional adjustments for variables reflecting fat mass (skinfolds or BMI) and ethnicity, the association disappeared with ethnicity having a much stronger effect than the adiposity variables. We got similar results exploring effects on other measures of glucose metabolism and when change in 25(OH)D from inclusion to 28 GW was taken into account.

CONCLUSIONS

Vitamin D deficiency was not associated with GDM or glucose metabolism in a multiethnic population-based study, after adjustments for confounding factors, in particular ethnicity.

Role of Placental VDR Expression and Function in Common Late Pregnancy Disorders

Vitamin D, besides its classical role in bone metabolism, plays a distinct role in multiple pathways of the feto-maternal unit. Calcitriol is the major active ligand of the nuclear vitamin D receptor (VDR). The vitamin D receptor (VDR) is expressed in different uteroplacental parts and exerts a variety of functions in physiologic pregnancy. It regulates decidualisation and implantation, influences hormone secretion and placental immune modulations. This review highlights the role of the vitamin D receptor in physiologic and disturbed pregnancy, as preeclampsia, fetal growth restriction, gestational diabetes and preterm birth. We discuss the existing literature regarding common VDR polymorphisms in these pregnancy disorders.

Status of Serum Vitamin D and Calcium Levels in Women of Reproductive Age in National Capital Territory of India

CONTEXT

In India, Vitamin D deficiency is a major public health problem, associated with lack of sunlight exposure in spite of abundant sunshine usually accompanied by reduced dietary intake. In women of reproductive age, Vitamin D deficiency in pregnancy has been associated with an increased risk of gestational diabetes mellitus, preeclampsia, maternal and perinatal morbidity and mortality.

AIMS

The aim of the present cross-sectional study was to evaluate the levels of serum Vitamin D 25(OH) D and calcium in women of reproductive age from India.

SETTINGS AND DESIGN

A cross-sectional study was carried on a total of 224 healthy nonpregnant and nonlactating women in the reproductive age group of 20-49 years.

MATERIALS AND METHODS

Demographic, socioeconomic class, and biochemical parameters for the estimation of serum 25(OH)D and calcium levels in women of reproductive age were studied.

STATISTICAL ANALYSIS

Statistical Package for Social Sciences version 20.0 was utilized for conducting the statistical analysis of the data.

RESULTS

Vitamin D deficiency (<20 ng/ml) was present in 88% of women. Women from middle socioeconomic class had the lowest mean serum 25(OH) D levels (9.6 ± 6 ng/ml) as compared to women from upper middle (11.4 ± 8 ng/ml), lower (11.2 ± 8 ng/ml), and upper (10 ± 8.6 ng/ml) socioeconomic class. Serum calcium levels were found in the normal range of 8.5-10.5 mg/dl for all the study subjects.

CONCLUSIONS

There is a high prevalence of hypovitaminosis D among women of reproductive age. These women may possibly have a higher risk of development of osteoporosis and pregnancy-related complications in future life.

Relationship between vitamin D and gestational diabetes in overweight or obese pregnant women may be mediated by adiponectin

SCOPE

Maternal vitamin D deficiency has been implicated in adverse pregnancy outcomes. However, the association between vitamin D and inflammation, particularly adipokines, remains unexplored in pregnancy.

METHODS AND RESULTS

In 102 overweight or obese pregnant women at high-risk of gestational diabetes mellitus (GDM), we investigated relationships between maternal 25-hydroxyvitamin D (25(OH)D) concentrations at 12-15 wk gestation (baseline) and serum lipids, inflammatory markers, novel adipokines (omentin-1, visfatin, high molecular weight (HMW) adiponectin), and subsequent pregnancy outcomes (GDM, preeclampsia, preterm birth [PTB]). After adjustment for maternal factors (age, BMI, parity, ethnicity, and smoking status), baseline 25(OH)D concentrations were inversely associated with total cholesterol and triglycerides, and positively associated with HMW-adiponectin. Higher baseline 25(OH)D concentrations were associated with decreased fasting and 1-h post-OGTT glucose and reduced risk of GDM at 26-28 wk, as well as with longer gestation and reduced risk of PTB upon additional adjustment for caesarean section. Adding HMW-adiponectin to the multivariable models attenuated most associations, and HMW-adiponectin was a significant predictor in the models.

CONCLUSION

Our findings suggest that lower maternal 25(OH)D concentrations in overweight/obese pregnant women at high-risk of GDM are associated with increased cardiometabolic risks during pregnancy and adverse pregnancy outcomes, and that these associations may be mediated by HMW-adiponectin.

Association of vitamin D intake and serum levels with fertility: results from the Lifestyle and Fertility Study

OBJECTIVE

To evaluate the role of vitamin D intake and serum levels on conception of clinical pregnancy and live birth.

DESIGN

Prospective cohort study.

SETTING

Academic medical centers.

PATIENT(S)

Healthy, nulliparous women, age 18-39 years, and their male partners.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy and live birth were compared between those who did or did not meet the vitamin D estimated average requirement (EAR) intake (10 μg/d) and with serum 25-hydroxyvitamin D (25(OH)D) considered at risk for inadequacy or deficiency (<50 nmol/L) or sufficient (≥50 nmol/L).

RESULT(S)

Among 132 women, 37.1% did not meet the vitamin D EAR and 13.9% had serum levels at risk for inadequacy or deficiency. Clinical pregnancies were significantly higher among women who met the vitamin D EAR (67.5% vs. 49.0%) and with sufficient serum 25(OH)D (64.3% vs. 38.9%) compared with those who did not. Live births were higher among those who met the vitamin D EAR (59.0% vs. 40.0%). The adjusted odds ratio (AOR) of conceiving a clinical pregnancy was significantly higher among those who met the EAR (AOR = 2.26; 95% confidence interval [CI], 1.05-4.86) and had sufficient serum 25(OH)D (AOR = 3.37; 95% CI, 1.06-10.70). The associations were not significant after controlling for selected nutrients and dietary quality.

CONCLUSION(S)

Women with vitamin D intake below EAR and serum 25(OH)D levels at risk for inadequacy or deficiency may be less likely to conceive and might benefit from increased vitamin D intake to achieve adequacy.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00642590.

Glucose homeostasis, beta cell function, and insulin resistance in relation to vitamin D status after gestational diabetes mellitus

INTRODUCTION

We wanted to determine vitamin D status after gestational diabetes mellitus (GDM) and to evaluate whether levels of 25-hydroxyvitamin D₃ (25OHD₃ ) are associated with beta cell function, insulin resistance or a diagnosis of diabetes after GDM.

MATERIAL AND METHODS

Glucose homeostasis was assessed during a 75-g oral glucose tolerance test one to two years after delivery in 376 women with previous GDM (287 European and 78 non-European, including 33 Arab and 35 Asian women). Insulin resistance was estimated using homeostasis model assessment of insulin resistance (HOMA-IR). The insulinogenic index (I/G30) and the disposition index [(I/G30)/HOMA-IR] were used to calculate insulin secretion. Concentrations of serum 25OHD₃ were determined.

RESULTS

Mean (±SD) 25OHD₃ concentration was 50.0 ± 22.3 nmol/L and differed significantly among subgroups of body mass index, ethnicity, and glucose tolerance status; 53% had 25OHD₃ levels <50 nmol/L and 87% had 25OHD₃ levels <75 nmol/L. There was a negative correlation between 25OHD₃ concentration and HOMA-IR (p < 0.001) and a positive correlation between 25OHD₃ and disposition index (p = 0.002) in univariable regression analysis. Correlations attenuated after adjustment for body mass index. In univariable regression analysis, 25OHD₃ concentrations were significantly associated with diabetes after GDM (p = 0.004). However, in a multivariable model, non-European origin, HOMA-IR and insulinogenic index were significantly associated with postpartum diabetes, whereas 25OHD₃ concentrations were not.

CONCLUSION

Vitamin D deficiency/insufficiency in previous GDM cases appears to be associated with beta cell dysfunction and insulin resistance, but not with postpartum diabetes when factors well known to influence type-2 diabetes were adjusted for.

Risk factors for antenatal hypovitaminosis D in an urban district in Malaysia

Background

Pregnant women form one of the high risk groups facing hypovitaminosis D. Low level of vitamin D will affect directly or indirectly both mother and fetus. Screening vitamin D in the first trimester of pregnancy is important to determine the necessary preventive action. Therefore, this study was aimed to determine the prevalence of hypovitaminosis D and its risk factors among pregnant women in the first trimester.

Methods

A cross sectional study was carried out among first trimester pregnant women during their first antenatal visit. Samples were taken from different ethnicities in an urban district in Malaysia. A total of 396 respondents (99 % response rate) aged 18–40 years completed self–administered and guided questionnaire (characteristics and risk factors), validated semi-quantitative food frequency questionnaire for vitamin D in Malaysia (FFQ vitamin D/My), anthropometric measures (weight and height), blood test for serum 25(OH)D, skin measurement using Mexameter (MX 18) and Fitzpatrick Skin Type Chart Measurement (FSTCM). Data were analyzed to determine the association between risk factors and hypovitaminosis D.

Results

The prevalence of hypovitaminosis D (serum 25(OH)D < 50 nmol/L) was 90.4 % (358). The mean age of respondents was 28.06 ± 4.09 years old. The independent predictors of hypovitaminosis D were Malay ethnicity (OR 33.68; 95 % CI: 12.81, 88.56), Indian ethnicity (OR 16.86; 95 % CI: 3.78,75.20), secondary education (OR 12.12; 95 % CI: 2.71, 54.16) and tertiary education (OR 14.38; 95 % Cl: 3.31, 62.45).

Conclusion

Awareness should be raised among Malay and Indian pregnant women with secondary and tertiary education who consumed vitamin D (especially milk) poorly in order to prevent adverse health outcomes. Further studies need to be conducted among health care workers to determine their level of knowledge related to vitamin D, as they are front liner in detecting the hypovitaminosis D.

Impact of vitamin D deficiency on maternal and birth outcomes in the Saudi population: a cross-sectional study

Background

Low serum vitamin D [25(OH)D] has been associated with different health problems worldwide. However, its causal role in several diseases remains unclear. We aimed to correlate vitamin D status with maternal and neonatal outcomes in pregnant females.

Method

One thousand pregnant women were recruited during early labour from the labour ward of King Khaled University Hospital, Riyadh, Saudi Arabia. Detailed medical data of all participants were collected from their records. Delivery events and birth outcomes were also documented. Serum 25(OH)D levels were measured using an enzyme-linked immunosorbent assay. A receiver operating characteristic (ROC) curve was constructed to evaluate the ability of vitamin D levels to predict complicated pregnancies. Regression analysis was used to test the correlation between serum 25(OH)D levels and different variables.

Results

Most of the participants were Saudis (89.9 %) and housewives (85.1 %) and 86.4 % of them had vitamin D deficiency (mean: 30.46 ± 19.6 nmol/L). Gestational diabetes mellitus (GDM) was the commonest complication detected (11.1 %) while the history of miscarriage was elevated (24.5 %). There was no association between GDM and low 25(OH)D. Yet, there was a significant negative correlation between serum 25(OH)D levels and fasting blood glucose among females older than 35 years (r = −0.2, p = 0.03). Hypertensive disorders of pregnancy and pre-existing hypertension were less than 1.5 % of frequency. Nevertheless, they were only recorded in women with insufficient and deficient vitamin D. ROC curve revealed that 25(OH)D levels were not able to discriminate between normal and adverse pregnancy outcomes (AUROC curve: 0.51; 95 % confidence interval (CI): 0.44–0.58; p = 0.8).

Conclusion

Hypovitaminosis D, a highly prevalent health problem among pregnant females in Riyadh, has no relation to adverse pregnancy outcomes except for a higher prevalence of miscarriage in women with low 25(OH)D.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-0901-4) contains supplementary material, which is available to authorized users.

Hypovitaminosis D in pregnancy in the Mediterranean region: a systematic review

Despite high levels of sunshine, maternal hypovitaminosis D during pregnancy is prevalent in the Mediterranean region. The aim of this study is to systematically review trials that investigated vitamin D concentrations during pregnancy in this region, in order to determine predictors of hypovitaminosis D and explain this phenomenon. After applying inclusion/exclusion criteria, 15 studies were entered into the systematic review involving 2649 pregnant women and 820 neonates. The main outcome was maternal vitamin D status, assessed by serum 25-hydroxy-vitamin D (25(OH)D) concentrations. Possible predictors of the outcome included maternal age, body mass index (BMI), race, socioeconomic status, skin type, gestational age, sun exposure, calcium and vitamin D intake and supplementation, smoking status, parity and season of delivery. Studies differed widely in vitamin D deficiency criteria, method of measurement and outcomes. The prevalence of vitamin D insufficiency ranges from 9.3 to 41.4%, whereas that of vitamin D deficiency from 22.7 to 90.3%. A positive association with 25(OH)D concentrations exists for light skin color, white race, uncovered dressing pattern, maternal vitamin D supplementation and season of gestation (spring/summer). An inverse association exists for BMI and gestational age, whereas data for smoking and socioeconomic status are controversial. We concluded that vitamin D deficiency in pregnancy seems to be quite common, even in the Mediterranean region. Racial, social and cultural habits, as well as the absence of preventive supplementation/dietary strategies, seem to negate the benefits of sun exposure.