Vitamin D supplementation during pregnancy: state of the evidence from a systematic review of randomised trials

Vitamin D and reproductive disorders: a comprehensive review with a focus on endometriosis

Vitamin D is a fat-soluble steroid hormone that was initially known only for regulating calcium and phosphorus levels and maintaining bone health. However, it was later discovered that many organs express vitamin D metabolizing enzymes and have a ligand for vitamin D, which regulates the expression of an extensive assortment of genes. As a result, vitamin D is indispensable for the proper function of organs, and its deficiency is believed to be a critical factor in symptoms and disorders such as cardiovascular diseases, autoimmune diseases, and cancers. The significance of vitamin D in reproductive tissues was recognized later, and studies have revealed its crucial role in male and female fertility, as well as proper reproductive function during pregnancy. Vitamin D deficiency has been identified as a risk factor for infertility, gonadal cancers, pregnancy complications, polycystic ovary syndrome, and endometriosis. However, data investigating the association between vitamin D levels and reproductive disorders, including endometriosis, have encountered inconsistencies. Therefore, the present study aims to review existing research on the effect of vitamin D on proper reproductive function, and the role of deficiency in reproductive diseases and specifically focuses on endometriosis.

Loss of 24-hydroxylated catabolism increases calcitriol and fibroblast growth factor 23 and alters calcium and phosphate metabolism in fetal mice

Calcitriol circulates at low levels in normal human and rodent fetuses, in part due to increased 24-hydroxylation of calcitriol and 25-hydroxyvitamin D by 24-hydroxylase (CYP24A1). Inactivating mutations of CYP24A1 cause high postnatal levels of calcitriol and the human condition of infantile hypercalcemia type 1, but whether the fetus is disturbed by the loss of CYP24A1 is unknown. We hypothesized that loss of Cyp24a1 in fetal mice will cause high calcitriol, hypercalcemia, and increased placental calcium transport. The Cyp24a1+/- mice were mated to create pregnancies with wildtype, Cyp24a1+/-, and Cyp24a1 null fetuses. The null fetuses were hypercalcemic, modestly hypophosphatemic (compared to Cyp24a1+/- fetuses only), with 3.5-fold increased calcitriol, 4-fold increased fibroblast growth factor 23 (FGF23), and unchanged parathyroid hormone. The quantitative RT-PCR confirmed the absence of Cyp24a1 and 2-fold increases in S100g, sodium-calcium exchanger type 1, and calcium-sensing receptor in null placentas but not in fetal kidneys; these changes predicted an increase in placental calcium transport. However, placental 45Ca and 32P transport were unchanged in null fetuses. Fetal ash weight and mineral content, placental weight, crown-rump length, and skeletal morphology did not differ among the genotypes. Serum procollagen 1 intact N-terminal propeptide and bone expression of sclerostin and Blgap were reduced while calcitonin receptor was increased in nulls. In conclusion, loss of Cyp24a1 in fetal mice causes hypercalcemia, modest hypophosphatemia, and increased FGF23, but no alteration in skeletal development. Reduced incorporation of calcium into bone may contribute to the hypercalcemia without causing a detectable decrease in the skeletal mineral content. The results predict that human fetuses bearing homozygous or compound heterozygous inactivating mutations of CYP24A1 will also be hypercalcemic in utero but with normal skeletal development.

Consensus Statement on Vitamin D Status Assessment and Supplementation: Whys, Whens, and Hows

The 6th International Conference, "Controversies in Vitamin D," was convened to discuss controversial topics, such as vitamin D metabolism, assessment, actions, and supplementation. Novel insights into vitamin D mechanisms of action suggest links with conditions that do not depend only on reduced solar exposure or diet intake and that can be detected with distinctive noncanonical vitamin D metabolites. Optimal 25-hydroxyvitamin D (25(OH)D) levels remain debated. Varying recommendations from different societies arise from evaluating different clinical or public health approaches. The lack of assay standardization also poses challenges in interpreting data from available studies, hindering rational data pooling and meta-analyses. Beyond the well-known skeletal features, interest in vitamin D's extraskeletal effects has led to clinical trials on cancer, cardiovascular risk, respiratory effects, autoimmune diseases, diabetes, and mortality. The initial negative results are likely due to enrollment of vitamin D-replete individuals. Subsequent post hoc analyses have suggested, nevertheless, potential benefits in reducing cancer incidence, autoimmune diseases, cardiovascular events, and diabetes. Oral administration of vitamin D is the preferred route. Parenteral administration is reserved for specific clinical situations. Cholecalciferol is favored due to safety and minimal monitoring requirements. Calcifediol may be used in certain conditions, while calcitriol should be limited to specific disorders in which the active metabolite is not readily produced in vivo. Further studies are needed to investigate vitamin D effects in relation to the different recommended 25(OH)D levels and the efficacy of the different supplementary formulations in achieving biochemical and clinical outcomes within the multifaced skeletal and extraskeletal potential effects of vitamin D.

Effectiveness of Vitamin D supplementation in combination with calcium on risk of maternal and neonatal outcomes: A quasi-experimental clinical trial

Objectives

We examined the effectiveness of combining Vitamin D supplementation with calcium on maternal and neonatal outcomes, as opposed to using Vitamin D supplements alone.

Materials and Methods

Pregnant women in their third trimester were divided into two groups. The control group received a daily dose of 1000 IU of Vitamin D, but, the experimental group received a combined daily dosage of 1000 IU of Vitamin D and 500 mg of calcium, until delivery.

Results

The women in the Vitamin D + calcium group were less likely to develop gestational diabetes (2.78%; vs. 19.51%; P = 0.0318), preeclampsia (2.78% vs. 26.83%; P = 0.004), newly onset gestational hypertension (11.11% vs. 46.34%; P = 0.001), proteinuria (5.56% vs. 39.02%; P = 0.0004), and impaired glucose tolerance (2.78% vs. 21.95%; P = 0.0163) and had lower blood pressure at 20th and 39th weeks of gestation. The newborns in the Vitamin D + calcium group were less likely to experience low birth weight (5.71% vs. 31.58%; P = 0.0066), low birth length (5.71% vs. 44.74%; P = 0.0007), were less likely to be admitted to the neonatal intensive care unit (14.29% vs. 42.11%; P = 0.0105), have a larger head circumference (35.00 vs. 33.63; P < 0.0001), longer gestational age at birth (40.0 vs. 37.56 weeks; P < 0.0001), and higher APGAR scores (9.58 vs. 6.31; P < 0.0001.) compared to Vitamin D group, respectively.

Conclusions

Taking Vitamin D and calcium by pregnant women in the third trimester is an effective treatment to decrease maternal, fetal, and neonatal outcomes.

Prenatal but not continued postpartum vitamin D supplementation reduces maternal bone resorption as measured by C-terminal telopeptide of type 1 collagen without effects on other biomarkers of bone metabolism

Vitamin D is a key regulator of bone mineral homeostasis and may modulate maternal bone health during pregnancy and postpartum. Using previously-collected data from the Maternal Vitamin D for Infant Growth (MDIG) trial in Dhaka, Bangladesh, we aimed to investigate the effects of prenatal and postpartum vitamin D3 supplementation on circulating biomarkers of bone formation and resorption at delivery and 6 months postpartum. MDIG trial participants were randomized to receive a prenatal;postpartum regimen of placebo or vitamin D3 (IU/week) as either 0;0 (Group A), 4200;0 (B), 16,800;0 (C), 28,000;0 (D) or 28,000;28,000 (E) from 17 to 24 weeks' gestation to 6 months postpartum. As this sub-study was not pre-planned, the study sample included MDIG participants who had data for at least 1 biomarker of interest at delivery or 6 months postpartum, with a corresponding baseline measurement (n = 690; 53 % of 1300 enrolled trial participants). Biomarkers related to bone turnover were measured in maternal venous blood samples collected at enrolment, delivery, and 6 months postpartum: osteoprotegerin (OPG), osteocalcin (OC), receptor activator nuclear factor kappa-B ligand (RANKL), fibroblast growth factor 23 (FGF23), procollagen type 1 N-terminal propeptide, (P1NP) and carboxy terminal telopeptide of type 1 collagen (CTx). Supplementation effects were expressed as percent differences between each vitamin D group and placebo with 95 % confidence intervals (95 % CI). Of 690 participants, 64 % had 25-hydroxyvitamin D concentrations (25OHD) <30 nmol/L and 94 % had 25OHD < 50 nmol/L at trial enrolment. At delivery, mean CTx concentrations were 27 % lower in group E versus placebo (95 % CI: -38, -13; P < 0.001), adjusting for enrolment concentrations. However, at 6 months postpartum, CTx concentrations were not statistically different in group E versus placebo (14 %; 95 % CI: -5.3, 37; P = 0.168), adjusting for delivery CTx concentrations. Effects on other biomarkers at delivery or postpartum were not statistically significant. In conclusion, prenatal high-dose vitamin D supplementation reduced bone resorption during pregnancy, albeit by only one biomarker, and without evidence of a sustained effect in the postpartum period. However, further evidence is needed to substantiate potential maternal bone health benefits of vitamin D in the postpartum period.

Micronutrient status in children aged 6-59 months with severe wasting and/or nutritional edema: implications for nutritional rehabilitation formulations

Undernutrition remains a global struggle and is associated with almost 45% of deaths in children younger than 5 years. Despite advances in management of severe wasting (though less so for nutritional edema), full and sustained recovery remains elusive. Children with severe wasting and/or nutritional edema (also commonly referred to as severe acute malnutrition and part of the umbrella term "severe malnutrition") continue to have a high mortality rate. This suggests a likely multifactorial etiology that may include micronutrient deficiency. Micronutrients are currently provided in therapeutic foods at levels based on expert opinion, with few supportive studies of high quality having been conducted. This narrative review looks at the knowledge base on micronutrient deficiencies in children aged 6-59 months who have severe wasting and/or nutritional edema, in addition to highlighting areas where further research is warranted (See "Future Directions" section).

[Preeclampsia: Guidelines for clinical practice from the French College of Obstetricians and Gynecologists]

OBJECTIVE

To identify strategies to reduce maternal and neonatal morbidity related to preeclampsia.

MATERIAL AND METHODS

The quality of evidence of the literature was assessed following the GRADE® method with questions formulated in the PICO format (Patients, Intervention, Comparison, Outcome) and outcomes defined a priori and classified according to their importance. An extensive bibliographic search was performed on PubMed, Cochrane, EMBASE and Google Scholar databases. The quality of the evidence was assessed (high, moderate, low, very low) and recommendations were formulated as a (i) strong, (ii) weak or (iii) no recommendation. The recommendations were reviewed in two rounds with external reviewers (Delphi survey) to select the consensus recommendations.

RESULTS

Preeclampsia is defined by the association of gestational hypertension (systolic blood pressure≥140mmHg and/or diastolic blood pressure≥90mmHg) and proteinuria≥0.3g/24h or a Proteinuria/Creatininuria ratio≥30mg/mmol occurring after 20 weeks of gestation. Data from the literature do not show any benefit in terms of maternal or perinatal health from implementing a broader definition of preeclampsia. Of the 31 questions, there was agreement between the working group and the external reviewers on 31 (100%). In general population, physical activity during pregnancy should be encouraged to reduce the risk of preeclampsia (Strong recommendation, Quality of the evidence low) but an early screening based on algorithms (Weak recommendation, Quality of the evidence low) or aspirin administration (Weak recommendation, Quality of the evidence very low) is not recommended to reduce maternal and neonatal morbidity related to preeclampsia. In women with preexisting diabetes or hypertension or renal disease, or multiple pregnancy, the level of evidence is insufficient to determine whether aspirin administration during pregnancy is useful to reduce maternal and perinatal morbidity (No recommendation, Quality of the evidence low). In women with a history of vasculo-placental disease, low dose of aspirin (Strong recommendation, Quality of the evidence moderate) at a dosage of 100-160mg per day (Weak recommendation, Quality of the evidence low), ideally before 16 weeks of gestation and not after 20 weeks of gestation (Strong recommendation, Quality of the evidence low) until 36 weeks of gestation (Weak recommendation, Quality of the evidence very low) is recommended. In a high-risk population, additional administration of low molecular weight heparin is not recommended (Weak recommendation, Quality of the evidence moderate). In case of preeclampsia (Weak recommendation, Quality of the evidence low) or suspicion of preeclampsia (Weak recommendation, Quality of the evidence moderate, the assessment of PlGF concentration or sFLT-1/PlGF ratio is not routinely recommended) in the only goal to reduce maternal or perinatal morbidity. In women with non-severe preeclampsia antihypertensive agent should be administered orally when the systolic blood pressure is measured between 140 and 159mmHg or diastolic blood pressure is measured between 90 and 109mmHg (Weak recommendation, Quality of the evidence low). In women with non-severe preeclampsia, delivery between 34 and 36+6 weeks of gestation reduces severe maternal hypertension but increases the incidence of moderate prematurity. Taking into account the benefit/risk balance for the mother and the child, it is recommended not to systematically induce birth in women with non-severe preeclampsia between 34 and 36+6 weeks of gestation (Strong recommendation, Quality of evidence high). In women with non-severe preeclampsia diagnosed between 37+0 and 41 weeks of gestation, it is recommended to induce birth to reduce maternal morbidity (Strong recommendation, Low quality of evidence), and to perform a trial of labor in the absence of contraindication (Strong recommendation, Very low quality of evidence). In women with a history of preeclampsia, screening maternal thrombophilia is not recommended (Strong recommendation, Quality of the evidence moderate). Because women with a history of a preeclampsia have an increased lifelong risk of chronic hypertension and cardiovascular complications, they should be informed of the need for medical follow-up to monitor blood pressure and to manage other possible cardiovascular risk factors (Strong recommendation, Quality of the evidence moderate).

CONCLUSION

The purpose of these recommendations was to reassess the definition of preeclampsia, and to determine the strategies to reduce maternal and perinatal morbidity related to preeclampsia, during pregnancy but also after childbirth. They aim to help health professionals in their daily clinical practice to inform or care for patients who have had or have preeclampsia. Synthetic information documents are also offered for professionals and patients.

Quantification and reporting of vitamin D concentrations measured in human milk by LC-MS/MS

Vitamin D is essential for optimal bone health, and vitamin D deficiency has been associated with an increased risk of adverse pregnancy, growth and developmental outcomes. In early life, and in the absence of endogenous vitamin D production from UVB light, infants are reliant on vitamin D stores established in utero and the vitamin D supply from human milk (HM). However, comprehensive data on vitamin D in HM is lacking. Thus, in this review we explore the application of liquid-chromatography tandem mass spectrometry (LC-MS/MS) to the assessment of vitamin D in HM. We discuss the challenges of extracting and measuring multiple vitamin D metabolites from HM including the frequent requirement for a large sample volume, and inappropriate poor sensitivity. Shortcomings in the reporting of experimental procedures and data analysis further hinder advances in the field. Data collated from all studies that have applied LC-MS/MS reveal that, in general, cholecalciferol concentration is greater and more variable than 25-hydroxyvitamin D concentration, and that the vitamin D content of HM is low and less than the currently recommended dietary requirement of infants, although maternal supplementation can increase the vitamin D content of HM. Improvements in analytical methods and their validation and larger, more representative studies are required to better characterize HM milk vitamin D metabolite concentrations and their relationship with maternal status. These data are essential to understand relationships with infant health and to inform public health policies around vitamin D fortification and supplementation.

Associations between maternal and infant selenium status and child growth in a birth cohort from Dhaka, Bangladesh

Deficiency of essential trace element, Se, has been implicated in adverse birth outcomes and in child linear growth because of its important role in redox biology and associated antioxidant effects. We used data from a randomised controlled trial conducted among a cohort of pregnant and lactating women in Dhaka, Bangladesh to examine associations between Se biomarkers in whole blood (WBSe), serum and selenoprotein P (SEPP1) in maternal delivery and venous cord (VC) blood. Associations between Se biomarkers, birth weight and infant growth outcomes (age-adjusted length, weight, head circumference and weight-for-length z-scores) at birth, 1 and 2 years of age were examined using regression analyses. WB and serum Se were negatively associated with birth weight (adjusted β, 95 % CI, WBSe delivery: −26·6 (–44·3, −8·9); WBSe VC: −19·6 (–33·0, −6·1)); however, delivery SEPP1 levels (adjusted β: −37·5 (–73·0, −2·0)) and VC blood (adjusted β: 82·3 (30·0, 134·7)) showed inconsistent and opposite associations with birth weight. Positive associations for SEPP1 VC suggest preferential transfer from mother to fetus. We found small associations between infant growth and WBSe VC (length-for-age z-score β, 95 % CI, at birth: −0·05 (–0·1, −0·01)); 12 months (β: −0·05 (–0·08, −0·007)). Weight-for-age z-score also showed weak negative associations with delivery WBSe (at birth: −0·07 (–0·1, −0·02); 12 -months: −0·05 (–0·1, −0·005)) and in WBSe VC (at birth: −0·05 (–0·08, −0·02); 12 months: −0·05 (–0·09, −0·004)). Given the fine balance between essential nutritional and toxic properties of Se, it is possible that WB and serum Se may negatively impact growth outcomes, both in utero and postpartum.

Clinical practice of vitamin D screening and supplementation in pregnancy in Asia-pacific countries: A cross-sectional study

Background

Vitamin D deficiency is common in pregnant women. There is scarce information in the Asia-Pacific region on the understanding of vitamin D screening and supplementation in pregnancy among health care professionals.

Methods

We performed a cross-sectional study among health care professionals who are part of the Integrated Platform for Research in Advancing Metabolic Health outcomes of Women and Children (IPRMAHO) international study group on their understanding and perception of Vitamin D screening and supplementation in pregnancy. The cross-sectional survey comprised 4 main sections: demographics, existing policies, nutrient supplementation in pregnancy and various practices on screening, treatment and perceptions, with a total of 22 questions. A total of 15 responses were obtained from attendees from distinct health facilities across eleven participating Asia-Pacific countries.

Results

Majority of the surveyed hospitals (11/15, 78.6 %) did not have a national policy or regional guideline regarding Vitamin D screening and supplementation in pregnancy. More than half of respondents were (9/14, 64.3 %) were unsure of the percentage of women seen with Vitamin D deficiencies each year and were unsure of Vitamin D dosage prescribed to pregnant women with (8/15, 53.3 %) or without (6/14, 42.9 %) Vitamin D deficiency. Vitamin D was rarely prescribed in pregnancy when compared to other nutrient supplements such as folic acid and iron. Majority of respondents (9/11, 72.7 %) indicated that their hospital did not screen for Vitamin D deficiencies in pregnancy, even amongst high risk pregnant women. Nevertheless, majority of respondents indicated a need (12/15, 80.0 %) for a guideline or consensus regarding Vitamin D screening and supplementation in pregnancy.

Conclusion

While majority of the surveyed hospitals did not have a national policy or regional guideline regarding Vitamin D screening and supplementation in pregnancy, majority of respondents indicated a need for the policy or guideline. There were varying clinical knowledge gaps and different perceptions on Vitamin D screening and supplementation in pregnancy among healthcare professionals.

Vitamin D Status as an Important Predictor of Preterm Birth in a Cohort of Black Women

Vitamin D deficiency (25 (OH)D < 20 ng/mL) is a modifiable risk factor that has been associated with an increased risk of preterm birth (PTB) (<37 weeks gestation). Black women are at a high risk for vitamin D deficiency due to higher melanin levels. Vitamin D sufficiency may be protective against PTB risk in Black women. Black participants between 8 and 25 weeks of gestation were included in this nested case-control study. The sample consisted of women who had either PTBs (n = 57) or term births, were selected based on maternal age compared to those who had PTBs (n = 118), and had blood samples available between 8 and 25 weeks of gestation. The women completed questionnaires about depressive symptoms and smoking behavior and had blood collected to determine their vitamin D levels. Gestational age at birth, hypertensive disorders, and body mass index (BMI) were collected from the medical records. The odds of PTB were increased by 3.34 times for participants with vitamin D deficiency after adjusting for hypertensive disorders of pregnancy and depressive symptoms. Vitamin D assessment and supplementation may be an important intervention for preventing PTB in pregnant Black women.

The Impact of Vitamin D Deficiency on Infants' Health

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

Impact of thyroid autoimmunity and vitamin D on in vitro fertilization/intracytoplasmic sperm injection outcomes among women with normal thyroid function

This prospective cohort study aimed to determine the impact of thyroid autoimmunity and total 25-hydroxyvitamin D concentration on early pregnancy outcomes in women undergoing in vitro fertilization/intracytoplasmic sperm injection who had intact thyroid function. The study included 1,297 women who underwent in vitro fertilization/intracytoplasmic sperm injection cycles, although only 588 patients received fresh embryo transfer. The study endpoints were clinical pregnancy, ongoing pregnancy, ectopic pregnancy, and early miscarriage rates. Our study found that the total 25-hydroxyvitamin D serum concentrations (P<0.001) and anti-Mullerian hormone levels (P=0.019) were lower among patients in the TAI group (n=518) than among those in the non-TAI group (n=779). Additionally, the study population in each group was divided into three subgroups according to the total vitamin D status based on clinical practice guidelines (deficient, <20 ng/mL; insufficient, 21-29 ng/mL; and sufficient, ≥30 ng/mL), TAI group: sufficient, n=144; insufficient, n=187; and deficient, n=187; non-TAI group: sufficient, n=329; insufficient, n=318, and deficient, n=133. In the TAI group, the number of good-quality embryos decreased in patients with vitamin D deficiency (P=0.007). Logistic regression analysis indicated that aging prevented women from achieving clinical (P=0.024) and ongoing pregnancy (P=0.026). The current findings suggest that patients with TAI had reduced serum vitamin D concentration. Furthermore, in the TAI group, the number of good-quality embryos decreased in patients with vitamin D deficiency. Finally, aging adversely impacted achieving clinical and ongoing pregnancy.

Effect of vitamin D supplementation on glucose control in mid-late gestation: A randomized controlled trial

BACKGROUND & AIMS

It is unclear whether vitamin D supplementation contributes to gestational glucose control and whether the specific effects vary in individuals with diverse genetic and metabolic contexts. The study aimed to assess the effect of vitamin D supplementation during pregnancy on subsequent glucose levels and to identify factors modulating the response to vitamin D3 intake.

METHODS

We conducted a multicenter randomized controlled trial, 1720 pregnant women recruited from the three antenatal clinics of Hefei city, China, who were allocated to receive either 1600 IU/d vitamin D3 (n = 858) or 400 IU/d vitamin D3 (n = 862) for 2 months at 24-28 weeks' gestation. Outcomes were changes in serum 25-hydroxyvitamin D (25(OH)D) and fasting plasma glucose (FPG) levels from baseline, 32-36 weeks' gestation to delivery (37-41 weeks) quantified using a linear mixed model.

RESULTS

After 2 months, FPG levels of the control group significantly increased by 0.22 mmol/L (from 4.6 [0.4] mmol/L to 4.8 [1.2] mmol/L, P < 0.001) at delivery, but that of the intervention group had no significant variation (from 4.6 [0.4] mmol/L to 4.7 [1.1] mmol/L; between-group difference in changes, -0.2 mmol/L, 95% CI, -0.3 to -0.08, P = 0.015). And differences in FPG variation were found in participants with the ApaI SNP CC genotype, or BsmI-CC, TaqI-AA, FokI-AA, respectively. Pregnant women with basal 25(OH)D concentrations higher than 50 nmol/L subgroup showed the greatest decline in FPG levels (between-group difference, -0.3 mmol/L; 95% CI, -0.5 to -0.1, P < 0.001). Moreover, pregnant women with GDM, multiple pregnancies or who were overweight were more likely to have FPG decline from vitamin D treatment.

CONCLUSIONS

Vitamin D supplementation significantly protected glucose homeostasis in mid-late gestation, and glycemic response to vitamin D may be dependent on basal 25(OH)D status, VDR gene polymorphism or their metabolic profiles.

TRIAL REGISTRATION NUMBER

ChiCTR2100051914. URL OF REGISTRATION: http://www.chictr.org.cn/showproj.aspx?proj=134700.

Benefits of Vitamin D Supplementation on Pregnancy of Rats with Pregestational Diabetes and Their Offspring

Studies on vitamin D supplementation have been performed in experimental and clinical investigations considering gestational diabetes and/or vitamin D deficiency in pregnancy. However, the results are controversial and few present the effects and mechanisms of this micronutrient on pregestational diabetes. The objective of this study was to evaluate the effect of vitamin D on the pregnancy of rats with pre-existing diabetes and their fetuses. Pregestational diabetes was induced in Sprague-Dawley rats at birth. The adult diabetic and nondiabetic rats were orally administered with vitamin D (cholecalciferol) throughout the pregnancy. The diabetes status was monitored during pregnancy by an oral glucose tolerance test (OGTT). At the end of the pregnancy, pancreas and blood samples were collected for morphological analyses and lipid peroxidation measurements, respectively. The influence of vitamin D treatment on reproductive outcomes, fetal growth, and development were compared to those of untreated diabetic and nondiabetic pregnant rats. P < 0.05 was considered a significant statistical limit. The diabetic rats given vitamin D had a greater number of insulin-positive cells, contributing to reduced blood glucose levels and thiobarbituric acid reactive substance concentrations (TBARS-an indicator of membrane lipid peroxidation), and increased reduced thiol group levels, contributing to suitable intrauterine conditions for better fetal development, which was confirmed by higher fetal viability rates. Thus, this study shows the effects and mechanisms of vitamin D supplementation on pre-existing diabetes in pregnant rats, confirming its beneficial effects on maternal redox status and glycemic control, and the decline of adverse maternal-fetal repercussions.

A Prospective Analysis of Vitamin D Levels in Pregnant Women Diagnosed with Gestational Hypertension after SARS-CoV-2 Infection

The great majority of existing studies suggests that the prognosis and outcomes of SARS-CoV-2 infections are improved with adequate vitamin D levels, with or without supplementation. Simultaneously, whether vitamin D supplementation during pregnancy lessens the chance of developing gestational hypertension is controversial. The objective of the present research was to evaluate whether vitamin D levels during pregnancy differ substantially among pregnant women who develop gestational hypertension following SARS-CoV-2 infection. The current research was designed as a prospective cohort following the pregnant women admitted to our clinic with COVID-19 until 36 weeks of gestation. Total vitamin D (25(OH)D) levels were measured in the three study groups in which pregnant women with COVID-19 during pregnancy and a diagnosis of hypertension after 20 weeks of gestation were considered the group of cases (GH-CoV). The second group (CoV) included those with COVID-19 and no hypertension, while the third group (GH) included those with hypertension and no COVID-19. It was observed that 64.4% of SARS-CoV-2 infections in the group of cases occurred during the first trimester, compared to 29.2% in the first trimester among the controls who did not develop GH. Normal vitamin D levels were measured at admission in a significantly higher proportion of pregnant women without GH (68.8% in the CoV group vs. 47.9% in the GH-CoV group and 45.8% in the GH group). At 36 weeks of gestation, the median values of 25(OH)D in the CoV group was 34.4 (26.9-39.7) ng/mL compared to 27.9 (16.2-32.4) ng/mL in the GH-CoV group and 29.5 ng/mL (18.4-33.2) in the GH group, while the blood pressure measurements remained over 140 mmHg among the groups who developed GH. There was a statistically significant negative association between serum 25(OH)D levels and systolic blood pressure (rho = -0.295; p-value = 0.031); however, the risk of developing GH was not significantly higher among pregnant women with COVID-19 if the vitamin D levels were insufficient (OR = 1.19; p-value = 0.092) or deficient (OR = 1.26; p-value = 0.057). Although insufficient or deficient vitamin D among pregnant women with COVID-19 was not an independent risk factor for the development of GH, it is likely that an association between first-trimester SARS-CoV-2 infection and low vitamin D plays a key role in developing gestational hypertension.

Harmonization of maternal balanced energy-protein supplementation studies for individual participant data (IPD) meta-analyses - finding and creating similarities in variables and data collection

BACKGROUND

Public health and clinical recommendations are established from systematic reviews and retrospective meta-analyses combining effect sizes, traditionally, from aggregate data and more recently, using individual participant data (IPD) of published studies. However, trials often have outcomes and other meta-data that are not defined and collected in a standardized way, making meta-analysis problematic. IPD meta-analysis can only partially fix the limitations of traditional, retrospective, aggregate meta-analysis; prospective meta-analysis further reduces the problems.

METHODS

We developed an initiative including seven clinical intervention studies of balanced energy-protein (BEP) supplementation during pregnancy and/or lactation that are being conducted (or recently concluded) in Burkina Faso, Ethiopia, India, Nepal, and Pakistan to test the effect of BEP on infant and maternal outcomes. These studies were commissioned after an expert consultation that designed recommendations for a BEP product for use among pregnant and lactating women in low- and middle-income countries. The initiative goal is to harmonize variables across studies to facilitate IPD meta-analyses on closely aligned data, commonly called prospective meta-analysis. Our objective here is to describe the process of harmonizing variable definitions and prioritizing research questions. A two-day workshop of investigators, content experts, and advisors was held in February 2020 and harmonization activities continued thereafter. Efforts included a range of activities from examining protocols and data collection plans to discussing best practices within field constraints. Prior to harmonization, there were many similar outcomes and variables across studies, such as newborn anthropometry, gestational age, and stillbirth, however, definitions and protocols differed. As well, some measurements were being conducted in several but not all studies, such as food insecurity. Through the harmonization process, we came to consensus on important shared variables, particularly outcomes, added new measurements, and improved protocols across studies.

DISCUSSION

We have fostered extensive communication between investigators from different studies, and importantly, created a large set of harmonized variable definitions within a prospective meta-analysis framework. We expect this initiative will improve reporting within each study in addition to providing opportunities for a series of IPD meta-analyses.

Longitudinal Assessment of Serum 25-Hydroxyvitamin D Levels during Pregnancy and Postpartum-Are the Current Recommendations for Supplementation Sufficient?

(1) Background: Pregnant women are at risk of vitamin D deficiency. Data on pregnancy outcomes in women with vitamin D deficiency during pregnancy are controversial, and prospective longitudinal data on vitamin D deficiency with consistent definitions in pregnant women are scarce. (2) Methods: The aim of this prospective longitudinal cohort study was to investigate 25-hydroxyvitamin D levels over the course of pregnancy and postpartum in singleton and twin pregnancies with regard to dietary and supplemental vitamin D intake and environmental factors influencing vitamin D levels, evaluated by a standardized food frequency questionnaire. (3) Results: We included 198 healthy singleton and 51 twin pregnancies for analysis. A total of 967 study visits were performed over a 3-year period. Overall, 59.5% of pregnant women were classified as vitamin D deficient in the first trimester, 54.8% in the second trimester, 58.5% in the third trimester, 66.9% at birth, and 60% 12 weeks postpartum, even though 66.4% of the study population reported daily pregnancy vitamin intake containing vitamin D. Dietary vitamin D intake did not affect vitamin D levels significantly. (4) Conclusions: The majority of pregnant women evaluated in this study were vitamin D deficient, despite administration of pregnancy vitamins containing vitamin D. Individualized vitamin D assessment during pregnancy should be considered to ensure adequate supplementation and prevention of hypovitaminosis D.

Weight Changes, Nutritional Intake, Food Contaminants, and Supplements in Women of Childbearing Age, including Pregnant Women: Guidelines for Interventions during the Perinatal Period from the French National College of Midwives

Adequate maternal nutrition is crucial for a healthy pregnancy and optimal fetal growth. Many women in France of childbearing age start their pregnancy in an unfavorable nutritional status. Recent studies highlight the value of paying attention to weight issues from the preconceptional period. It is important to call attention to the need for folate supplementation and to promote a varied and balanced diet throughout pregnancy to cover essential nutritional needs.

Effects of vitamin D supplementation during pregnancy on bone health and offspring growth: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Whether vitamin D supplementation during pregnancy is beneficial to bone health and offspring growth remains controversial. Moreover, there is no universal agreement regarding the appropriate dose and the time of commencement of vitamin D supplementation during pregnancy.

OBJECTIVE

We aimed to systematically review the effects of vitamin D supplementation during pregnancy on bone development and offspring growth.

METHODS

A literature search for randomized controlled trials (RCTs) was performed in 7 electronic databases to identify relevant studies about the effects of vitamin D supplementation during pregnancy on bone development and offspring growth from inception to May 22, 2022. A Cochrane Risk Assessment Tool was used for quality assessment. Vitamin D supplementation was compared with placebo or standard supplements. The effects are presented as the mean differences (MDs) with 95% CIs. The outcomes include bone mineral content (BMC), bone mineral density (BMD), bone area (BA), femur length (FL) and humeral length (HL); measurement indicators of growth, including length, weight and head circumference; and secondary outcome measures, including biochemical indicators of bone health, such as the serum 25(OH)D concentration. Additionally, subgroup analyses were carried out to evaluate the impact of different doses and different initiation times of supplementation with vitamin D.

RESULTS

Twenty-three studies with 5390 participants met our inclusion criteria. Vitamin D supplementation during pregnancy was associated with increased humeral length (HL) (MD 0.13, 95% CI 0.06, 0.21, I2 = 0, P = 0.0007) during the fetal period (third trimester). Vitamin D supplementation during pregnancy was associated with a significantly increased length at birth (MD 0.14, 95% CI 0.04, 0.24, I2 = 24%, P = 0.005) and was associated with a higher cord blood 25(OH)D concentration (MD 48.74, 95% CI 8.47, 89.01, I2 = 100%, P = 0.02). Additionally, subgroup analysis revealed that birth length was significantly higher in the vitamin D intervention groups of ≤1000 IU/day and ≥4001 IU/day compared with the control group. Prenatal (third trimester) vitamin D supplementation was associated with a significant increase in birth length, while prenatal (second trimester) vitamin D supplementation was associated with a significant increase in birth weight.

CONCLUSION

Vitamin D supplementation during pregnancy may be associated with increased humeral length (HL) in the uterus, increased body length at birth and higher cord blood 25(OH)D concentration. Evidence of its effect on long-term growth in children is lacking. Additional rigorous high-quality, long-term and larger randomized trials are required to more fully investigate the effects of vitamin D supplementation during pregnancy.

Serum Vitamin D Concentrations, Time to Pregnancy, and Pregnancy Outcomes among Preconception Couples: A Cohort Study in Shanghai, China

BACKGROUND

The role of vitamin D in reproductive health is still unclear. This study aimed to assess the effect of serum 25-hydroxyvitamin D (25(OH)D), among preconception couples, on fecundity, and the associations between 25(OH)D concentrations before and during pregnancy, and pregnancy outcomes.

METHODS

200 preconception couples attempting to conceive were recruited and were followed-up until childbirth. Time to pregnancy was collected via telephone every two months or obtained via a questionnaire during pregnancy. Blood samples were collected to measure serum 25(OH)D levels from both partners at enrollment and from women during the second and third trimester of pregnancy.

RESULTS

Couples had higher conception rates within six months (adjusted odds ratio (aOR): 3.72, 95% CI: 1.16, 11.9) and reduced time to pregnancy (adjusted fecundability ratio (aFR): 1.50, 95% CI: 1.01, 2.23) if male partners had sufficient 25(OH)D compared with insufficient 25(OH)D. Compared to pregnant women with insufficient 25(OH)D in the third trimester of pregnancy, sufficient 25(OH)D was associated with reduced odds of anemia (OR: 0.22, 95% CI: 0.06, 0.82), longer gestational age (β: 0.53, 95% CI: 0.04, 1.01) and newborns' higher ponderal index (β: 0.10, 95% CI: 0.01, 0.19).

CONCLUSIONS

Sufficient serum 25(OH)D levels among preconception men or during pregnancy were associated with better reproductive health.

Impact of vitamin D on maternal and fetal health: A review

The role of vitamin D in improving maternal health and reducing the risk of developmental disorders in fetus has been an important domain of research since the past few years. Vitamin D, owing to its immunomodulatory, anti‐inflammatory, developmental roles, and regulating calcium homeostasis, is predicted to have a significant influence on maternal and fetal health status. Several observational studies and clinical trials, determining the impact of vitamin D on gestational diabetes, C‐section, postpartum depression, pre‐eclampsia, miscarriages, and preterm delivery, have been elaborated in this review. In addition, fetal birth defects including neurological development, reduced birth weight, respiratory infections, bone development, and altered anthropometrics have also been summarized with available evidences. Other important mechanisms related to the roles of vitamin D in the body are also explained. Furthermore, recent studies determining the effect of vitamin D at genetic level will also help in understanding and future design of research in the area of maternal and fetal health.

The role of prenatal vitamin D on the development of childhood asthma and wheeze: An umbrella review of systematic reviews and meta-analyses

BACKGROUND & OBJECTIVE

It has been suggested that prenatal vitamin D plays a role in the development of childhood asthma and wheeze. Several systematic reviews have been conducted, but the results are inconsistent, and the methodological quality has not been studied. Therefore, the objective of this umbrella review was to assess the internal validity of the evidence base and the evidence for an association between prenatal vitamin D and asthma or wheezing in the offspring.

METHODS

We searched the electronic databases Embase, PubMed, and Cochrane Library for studies on prenatal vitamin D using search words such as vitamin D, 25-hydroxyvitamin D, calcidiol, fetal, and neonatal. The search was conducted in June 2020, and the databases were searched from their date of establishment. We included systematic reviews and/or meta-analyses of experimental and observational studies assessing the association between prenatal vitamin D or asthma and wheeze. We excluded narrative reviews, commentaries, and other umbrella reviews. The methodological quality of systematic reviews was assessed using AMSTAR 2 tool. PROSPERO reg. no. CRD42020151329.

RESULTS

We identified 22 eligible systematic reviews (17 on asthma and 20 on wheeze). Using the AMSTAR 2 quality assessment tool, the methodological quality was rated as critically low in 21 out of 22 systematic reviews, suggesting that previous reviews and meta-analyses did not provide accurate and comprehensive summaries of the included studies and that conclusions reached were potentially flawed. The majority of the included reviews reported that prenatal vitamin D reduces the risk of wheeze in the offspring.

CONCLUSION

Prior to informing public guidelines, high-quality systematic reviews of the current evidence are greatly warranted.

Implementation strategies for improving vitamin D status and increasing vitamin D intake in the UK: current controversies and future perspectives: proceedings of the 2nd Rank Prize Funds Forum on vitamin D

A multi-disciplinary expert group met to discuss vitamin D deficiency in the UK and strategies for improving population intakes and status. Changes to UK Government advice since the 1st Rank Forum on Vitamin D (2009) were discussed, including rationale for setting a reference nutrient intake (10 µg/d; 400 IU/d) for adults and children (4+ years). Current UK data show inadequate intakes among all age groups and high prevalence of low vitamin D status among specific groups (e.g. pregnant women and adolescent males/females). Evidence of widespread deficiency within some minority ethnic groups, resulting in nutritional rickets (particularly among Black and South Asian infants), raised particular concern. Latest data indicate that UK population vitamin D intakes and status reamain relatively unchanged since Government recommendations changed in 2016. Vitamin D food fortification was discussed as a potential strategy to increase population intakes. Data from dose-response and dietary modelling studies indicate dairy products, bread, hens' eggs and some meats as potential fortification vehicles. Vitamin D3 appears more effective than vitamin D2 for raising serum 25-hydroxyvitamin D concentration, which has implications for choice of fortificant. Other considerations for successful fortification strategies include: (i) need for 'real-world' cost information for use in modelling work; (ii) supportive food legislation; (iii) improved consumer and health professional understanding of vitamin D's importance; (iv) clinical consequences of inadequate vitamin D status and (v) consistent communication of Government advice across health/social care professions, and via the food industry. These areas urgently require further research to enable universal improvement in vitamin D intakes and status in the UK population.

Interventions for the prevention of spontaneous preterm birth: a scoping review of systematic reviews

BACKGROUND

Globally, 11% of babies are born preterm each year. Preterm birth (PTB) is a leading cause of neonatal death and under-five mortality and morbidity, with lifelong sequelae in those who survive. PTB disproportionately impacts low/middle-income countries (LMICs) where the burden is highest.

OBJECTIVES

This scoping review sought to the evidence for interventions that reduce the risk of PTB, focusing on the evidence from LMICs and describing how context is considered in evidence synthesis.

DESIGN

We conducted a scoping review, to describe this wide topic area. We searched five electronic databases (2009-2020) and contacted experts to identify relevant systematic reviews of interventions to reduce the risk of PTB. We included published systematic reviews that examined the effectiveness of interventions and their effect on reducing the risk of PTB. Data were extracted and is described narratively.

RESULTS

139 published systematic reviews were included in the review. Interventions were categorised as primary or secondary. The interventions where the results showed a greater effect size and consistency across review findings included treatment of syphilis and vaginal candidiasis, vitamin D supplementation and cervical cerclage. Included in the 139 reviews were 1372 unique primary source studies. 28% primary studies were undertaken in LMIC contexts and only 4.5% undertaken in a low-income country (LIC) Only 10.8% of the reviews sought to explore the impact of context on findings, and 19.4% reviews did not report the settings or the primary studies.

CONCLUSION

This scoping review highlights the lack of research evidence derived from contexts where the burden of PTB globally is greatest. The lack of rigour in addressing contextual applicability within systematic review methods is also highlighted. This presents a risk of inappropriate and unsafe recommendations for practice within these contexts. It also highlights a need for primary research, developing and testing interventions in LIC settings.

Calcifediol (25OHD) Deficiency and Its Treatment in Women's Health and Fertility

Currently, there is abundant scientific evidence showing that the vitamin D endocrine system (VDES) is a highly complex endocrine system with multiple actions in different regions of the body. The unequivocal presence of vitamin D receptors in different tissues related to fertility, and to specific aspects of women’s health such as pregnancy, undoubtedly implies functions of this steroid hormone in both male and female fertility and establishes relationships with different outcomes of human gestation. In order to review the role of the VDES in human fertility, we evaluated the relationships established between 25-hydroxyvitamin D (calcifediol) deficiency and in vitro fertilization, as well as aspects related to ovarian reserve and fertility, and commonly diagnosed endocrinopathies such as polycystic ovary disease. Likewise, we briefly reviewed the relationships between calcifediol deficiency and uterine fibroids, as well as the role that treatment may have in improving human fertility. Finally, the best scientific evidence available on the consequences of calcifediol deficiency during pregnancy is reviewed in relation to those aspects that have accumulated the most scientific literature to date, such as the relationship with the weight of the newborn at the time of delivery, the appearance of preeclampsia, and the risk of developing gestational diabetes and its final consequences for the pregnancy. To date, there is no definitive consensus on the necessary dose for treatment of calcifediol deficiency in the therapeutic management of infertility or during pregnancy. Large prospective clinical intervention studies are needed to clarify the benefits associated with this supplementation and the optimal dose to use in each situation. Although most intervention studies to date have been conducted with cholecalciferol, due to its much longer history of use in daily care, the use of calcifediol to alleviate 25-hydroxyvitamin D deficiency seems safe, even during pregnancy. The unequivocal presence of vitamin D receptors in very different tissues related to human fertility, both male and female, as well as in structures typical of pregnancy, allows us to investigate the crucial role that this steroid hormone has in specific aspects of women’s health, such as pregnancy and the ability to conceive. Well-designed clinical studies are needed to elucidate the necessary dose and the best form of treatment to resolve the very common calcifediol deficiency in women of reproductive age.

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.

Estimate of Dietary Total Antioxidant Capacity of Pregnant Women and Associated Factors

OBJECTIVE

 To investigate the dietary total antioxidant capacity (DTAC) of pregnant women, and associated factors.

METHODS

 Cross-sectional study conducted with 785 pregnant adult women attended in primary health care centers of Ribeirão Preto, state of São Paulo, Brazil. Two 24-hour dietary recalls were obtained, and the usual intake was estimated through the Multiple Source Method. The DTAC was estimated using the ferric reducing antioxidant power assay. The relationship between the higher DTAC estimate (≥ median of 4.3 mmol/day) and associated factors was investigated using adjusted logistic models with backward selection.

RESULTS

 In total, 25% of the pregnant women were classified as overweight, and 32% as obese. The median (P25, P75) DTAC was 4.3 (3.3-5.6) mmol/day. Through adjusted logistic regression models with backward selection, a higher chance of DTAC estimates above the median among pregnant women aged ≥ 35 years old (2.01 [1.24-3.27]) was verified when compared with younger pregnant women. Women with prepregnancy overweight (0.63 [0.45-0.89]) and obesity (0.59 [0.40-0.88]) presented a lower chance of DTAC estimates above the median when compared with eutrophic pregnant women. A higher DTAC estimate was positively associated with the use of dietary supplements (1.39 [1.03-1.88]), and negatively associated with total dietary energy (0.59 [0.42-0.85]).

CONCLUSION

 The DTAC estimate over the median was associated with greater age, adequate body weight, use of dietary supplements, and lower energy intake.

An Update on Vitamin D Deficiency Status in Malaysia

Vitamin D is essential for maintaining serum calcium levels, ensuring sufficient bone mineralization, immunomodulatory properties, and a protective effect on the cardiovascular system, renal disease, cancer, as well as in pregnancy. Vitamin D deficiency is prevalent worldwide, and it is not related to a country's development index. However, the data on vitamin D deficiencies are primarily taken from out-of-date, small-scale studies on target age groups or specific diseases, rather than from large-scale, population-based surveys. In Malaysia, for the past 16 years, studies were conducted involving adult men and women, pregnant women, postmenopausal women, adolescent, and children especially with specific diseases such as spina bifida, epilepsy, chronic liver disease, and atopic dermatitis. Only a few large surveys were conducted involving children and adolescents. Across the specific target population studied, vitamin D deficiency and insufficiency were seen particularly among females, Indians, and those of Malay ethnicity. This is related to widely known causes of vitamin D deficiency such as skin type (melanin) and sun avoidant lifestyles that include covering clothes, largely practiced by Malay Muslims in Malaysia. Other related causes or the high-risk groups are breastfed infants, the elderly, the obese, those on medications, and those characterized by fat malabsorption and geophysical factors. Vitamin D deficiency can be managed with pharmacological or non-pharmacological approaches, depending on the severity. The objective is to raise serum vitamin D to a normal level, hence, relieving the symptoms and reducing the adverse health outcomes. Despite no clear guidelines in treating vitamin D deficiency in Malaysia, this condition can be prevented with taking adequate vitamin D in food resources, sun exposure, or supplementation. Special attention should be given to high-risk groups including infants, obese patients, and the elderly.

Impact evaluation of the efficacy of different doses of vitamin D supplementation during pregnancy on pregnancy and birth outcomes: a randomised, controlled, dose comparison trial in Pakistan

Background

Vitamin D deficiency during pregnancy is a public health problem in Pakistan and is prevalent among most women of reproductive age in the country. Vitamin D supplementation during pregnancy is suggested to prevent adverse pregnancy outcomes and vitamin D deficiency in both the mother and her newborn.

Methods

We conducted a double-blinded, randomised controlled trial in Karachi, Pakistan to evaluate the effect of different doses of vitamin D supplementation during pregnancy on biochemical markers (serum 25(OH)D, calcium, phosphorus and alkaline phosphatase) in women and neonates, and on pregnancy and birth outcomes (gestational diabetes, pre-eclampsia, low birth weight, preterm births and stillbirths).

Results

Pregnant women (N=350) in their first trimester were recruited and randomised to three treatment groups of vitamin D supplementation: 4000 IU/day (group A, n=120), 2000 IU/day (group B, n=115) or 400 IU/day (group C, n=115). Women and their newborn in group A had the lowest vitamin D deficiency at endline (endline: 75.9%; neonatal: 64.9%), followed by group B (endline: 84.9%; neonatal: 73.7%) and then the control group (endline: 90.2%; neonatal: 91.8%). Vitamin D deficiency was significantly lower in group A than in group C (p=0.006) among women at endline and lower in both groups A and B than in the control group (p=0.001) in neonates. Within groups, serum 25(OH)D was significantly higher between baseline and endline in group A and between maternal baseline and neonatal levels in groups A and B. Participant serum 25(OH)D levels at the end of the trial were positively correlated with those in intervention group A (4000 IU/day) (β=4.16, 95% CI 1.6 to 6.7, p=0.002), with food group consumption (β=0.95, 95% CI 0.01 to 1.89, p=0.047) and with baseline levels of serum 25(OH)D (β=0.43, 95% CI 0.29 to 0.58, p<0.0001).

Conclusion

The evidence provided in our study indicates that vitamin D supplementation of 4000 IU/day was more effective in reducing vitamin D deficiency among pregnant women and in improving serum 25(OH)D levels in mothers and their neonates compared with 2000 IU/day and 400 IU/day.

Trial registration number NCT02215213.

Low Maternal Serum 25-Hydroxyvitamin D Concentration Is Associated With Postpartum Hemorrhage: A Retrospective Observational Study

OBJECTIVE

The primary aim of this study is to investigate the relationship between vitamin D serum level and the incidence of postpartum hemorrhage (PPH). The secondary objective is to determine the relative risk of low vitamin D associated with PPH.

METHODS

This was a retrospective observational study. A total of 600 women who had delivered their babies in a single tertiary teaching hospital were enrolled. Serum blood test for 25(OH)D was performed at 35 + 0 to 36 + 6 weeks of pregnancy to measure vitamin D. A 25(OH)D level < 20 ng/mL was defined as vitamin D deficient, and a level 21-29 ng/mL as insufficient.

RESULTS

Vitamin D levels were deficient in 145 (24.1%) and insufficient in 254 (42.3%) of the women tested. Women with deficient and insufficient vitamin D levels were significantly younger than those with sufficient vitamin D levels (p < 0.001). The overall rates of PPH in the deficient and insufficient groups were 6.9% (10/145) and 6.7% (17/254), respectively, and were significantly higher than the rate of the normal vitamin D group (1.5%, p = 0.009). Women with sufficient vitamin D levels had significantly higher hemoglobin levels than those with low vitamin D levels. Higher vitamin D levels were associated with a significantly low risk of PPH (AOR: 0.93, CI: 0.89-0.98, p = 0.006).

CONCLUSION

Our results suggest that a low vitamin D level is a risk factor for PPH. Low vitamin D also related to high risk of low hemoglobin before delivery. Thus, antepartum care should include vitamin D supplements for all women if possible.

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.

Vitamin D deficiency and anemia in pregnant women: a systematic review and meta-analysis

CONTEXT

Epidemiological studies suggest an association between vitamin D deficiency and anemia. Evidence of this relationship in pregnant women, however, is scarce.

OBJECTIVE

The aim of this systematic review was to investigate the association between vitamin D deficiency and gestational anemia through observational studies.

DATA SOURCES

The PubMed, Scopus, Web of Science, ScienceDirect, Embase, and Virtual Health Library databases were searched from inception to April 2021.

STUDY SELECTION

Original articles reporting observational studies that investigated the association between vitamin D deficiency and gestational anemia were included. Articles that did not have an abstract, as well as reviews articles, experimental studies, and editorials, were excluded. Two reviewers independently performed study selection, data extraction, and assessment of study quality. Disagreements between the reviewers were resolved by a third reviewer.

DATA EXTRACTION

Study quality was assessed by 2 scales. Data were extracted from eligible studies and arranged in a 2 × 2 table. Odds ratios with 95% confidence intervals for the risk of the outcome were estimated using a fixed-effect model.

RESULTS

In total, 985 studies were retrieved, of which 17 were included in the systematic review: 11 cohort studies, 3 case-control studies, and 3 cross-sectional studies. For the meta-analysis, 8 studies with a total of 6530 women were included. There was a 61% increase in the odds of anemia in pregnant women with vitamin D deficiency (OR = 1.61; 95%CI, 1.41-1.83; I2 = 48%).

CONCLUSIONS

Vitamin D deficiency may be a risk factor for anemia in pregnant women.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020182697.

Maternal vitamin D deficiency and GDM risk: evidence for the case of investing more attention in antenatal clinics

Gestational diabetes mellitus (GDM) is a global public health problem, and in India, it affects about 20% of pregnancies. India, despite being a tropical country with abundant sunshine has a high prevalence (80%) of vitamin D deficiency (VDD) among reproductive-aged women. Global and Indian evidence links VDD with a higher risk of hyperglycaemia in pregnancy and GDM. VDD has also been implicated in gestational hypertension, preterm birth and poorer offspring health. Global scientific consensus acknowledges the need for maternal vitamin D screening and supplementation, but knowledge gaps exist about optimal blood levels (50-100 nmol/l), and the required vitamin D dosage (400-4000 IU). Diet can provide <10% of the vitamin D requirements, food fortification can deliver limited amounts, and hence optimal antenatal supplementation is key. Prenatal calcium supplements containing 400 IU of vitamin D may be sufficient for calcium absorption and bone health, but may not provide immunomodulatory benefits, including GDM prevention. Increasing evidence calls for higher maternal vitamin D requirements (2000-4000 IU) for skeletal, metabolic and immune health benefits. Current screening and supplementation for maternal VDD in India is low. We need to invest in future studies to determine optimal maternal vitamin D requirements and formulate policies for vitamin D supplementation to prevent GDM. Improving the maternal vitamin D status is an important nutritional priority for policymakers to reduce the large economic burden of non-communicable diseases (10% of India's gross domestic product), and eventually achieve the 2030 UN sustainable development goals.

Vitamin D recommendations in clinical guidelines: A systematic review, quality evaluation and analysis of potential predictors

BACKGROUND

Vitamin D has been widely promoted for bone health through supplementation and fortification of the general adult population. However, there is growing evidence that does not support these strategies. Our aim is to review the quality and recommendations on vitamin D nutritional and clinical practice guidelines and to explore predictive factors for their direction and strength.

METHODS

We searched three databases and two guideline repositories from 2010 onwards. We performed a descriptive analysis, a quality appraisal using AGREE II scores (Appraisal of Guidelines Research and Evaluation) and a bivariate analysis evaluating the association between direction and strength of recommendations, AGREE II domains' scores and pre-specified characteristics.

RESULTS

We included 34 guidelines, 44.1% recommended, 26.5% suggested and 29.4% did not recommend vitamin D supplementation. Guidelines that scored higher for "editorial independence" and "overall quality score" were less likely to recommend or suggest vitamin D supplementation (median 68.8 vs 35.4; P = .001 and 58.3 vs 37.5; P = .02). Guidance produced by government organisations and those that reported source of funding were associated with higher AGREE II scores. Unclear role of source of funding was associated with recommending or suggesting vitamin D supplementation (P = .034). Editorial independence was an independent predictor for recommending or suggesting vitamin D supplementation (OR 1.09; CI95% 1.02 to 1.16; P = .006).

CONCLUSIONS

Policymakers, clinicians and patients should be aware that lower quality guidelines and those reporting conflicts of interest are more likely to promote vitamin D supplementation. Guideline organisations should improve the quality of their recommendations' development and the management of conflicts of interest. Users and editors should be aware of these findings when using and appraising guidelines.

Could Vitamin D Be Effective in Prevention of Preeclampsia?

Prevention of preeclampsia (PE) remains one of the most significant problems in perinatal medicine. Due to the possible unpredictable course of hypertension in pregnancy, primarily PE and the high complication rate for the mother and fetus/newborn, it is urgent to offer pregnant women in high-risk groups effective methods of preventing the PE development or delaying its appearance. In addition, due to the association of PE with an increased risk of developing cardiovascular diseases (CVD) in later life, effective preeclampsia prevention could also be important in reducing their incidence. Ideal PE prophylaxis should target the pathogenetic changes leading to the development of PE and be safe for the mother and fetus, inexpensive and freely available. Currently, the only recognized method of PE prevention recommended by many institutions around the world is the use of a small dose of acetylsalicylic acid in pregnant women with risk factors. Unfortunately, some cases of PE are diagnosed in women without recognized risk factors and in those in whom prophylaxis with acetylsalicylic acid is not adequate. Hence, new drugs which would target pathogenetic elements in the development of preeclampsia are studied. Vitamin D (Vit D) seems to be a promising agent due to its beneficial effect on placental implantation, the immune system, and angiogenic factors. Studies published so far emphasize the relationship of its deficiency with the development of PE, but the data on the benefits of its supplementation to reduce the risk of PE are inconclusive. In the light of current research, the key issue is determining the protective concentration of Vit D in a pregnant woman. The study aims to present the possibility of using Vit D to prevent PE, emphasizing its impact on the pathogenetic elements of preeclampsia development.

Genetic Link Determining the Maternal-Fetal Circulation of Vitamin D

Vitamin D is an essential micronutrient whose demand is heightened during pregnancy to support the growth of the fetus. Furthermore, the fetus does not produce vitamin D and hence relies exclusively on the supply of maternal vitamin D through the placenta. Vitamin D inadequacy is linked with pregnancy complications and adverse infant outcomes. Hence, early predictive markers of vitamin D inadequacy such as genetic vulnerability are important to both mother and offspring. In this multi-ethnic Asian birth cohort study, we report the first genome-wide association analysis (GWAS) of maternal and fetal vitamin D in circulation. For this, 25-hydroxyvitamin D (25OHD) was measured in the antenatal blood of mothers during mid gestation (n=942), and the cord blood of their offspring at birth (n=812). Around ~7 million single nucleotide polymorphisms (SNPs) were regressed against 25OHD concentrations to identify genetic risk variants. About 41% of mothers had inadequate 25OHD (≤75nmol/L) during pregnancy. Antenatal 25OHD was associated with ethnicity [Malay (Β=−22.32nmol/L, p=2.3×10⁻²⁶); Indian (Β=−21.85, p=3.1×10⁻²¹); reference Chinese], age (Β=0.47/year, p=0.0058), and supplement intake (Β=16.47, p=2.4×10⁻¹³). Cord blood 25OHD highly correlated with antenatal vitamin D (r=0.75) and was associated with ethnicity [Malay (Β=−4.44, p=2.2×10⁻⁷); Indian (Β=−1.99, p=0.038); reference Chinese]. GWAS analysis identified rs4588, a missense variant in the group-specific component (GC) gene encoding vitamin D binding protein (VDBP), and its defining haplotype, as a risk factor for low antenatal (Β=−8.56/T-allele, p=1.0×10⁻⁹) and cord blood vitamin D (Β=−3.22/T-allele, p=1.0×10⁻⁸) in all three ethnicities. We also discovered a novel association in a SNP downstream of CYP2J2 (rs10789082), a gene involved in 25-hydroxylation of vitamin D, with vitamin D in pregnant women (Β=−7.68/G-allele, p=1.5×10⁻⁸), but not their offspring. As the prevention and early detection of suboptimal vitamin D levels are of profound importance to both mother and offspring’s health, the genetic risk variants identified in this study allow risk assessment and precision in early intervention of vitamin D deficiency.

Single oral dose of vitamin D3 supplementation prior to in vitro fertilization and embryo transfer in normal weight women: the SUNDRO randomized controlled trial

BACKGROUND

Improving in vitro fertilization success is an unmet need. Observational studies have suggested that women with deficient or insufficient vitamin D have lower chances of in vitro fertilization success, but whether supplementation improves clinical pregnancy rate remains unclear.

OBJECTIVE

This study aimed to determine whether oral vitamin D₃ supplementation improves clinical pregnancy in women undergoing an in vitro fertilization cycle.

STUDY DESIGN

The "supplementation of vitamin D and reproductive outcome" trial is a 2-center randomized superiority double-blind placebo-controlled trial. Subjects were recruited between October 2016 and January 2019. Participants were women aged 18 to 39 years with low vitamin D (peripheral 25-hydroxyvitamin D of <30 ng/mL), serum calcium of ≥10.6 mg/dL, body mass index of 18 to 25 kg/m², and antimüllerian hormone levels of >0.5 ng/mL and starting their first, second, or third treatment cycle of conventional in vitro fertilization or intracytoplasmic sperm injection. The primary outcome was the cumulative clinical pregnancy rate per cycle. Pregnancies obtained with both fresh or frozen embryo transfers were included. Clinical pregnancy was defined as an intrauterine gestational sac with a viable fetus. The primary analysis was performed according to the intention-to-treat principle and could also include natural conceptions. Secondary outcomes included total dose of gonadotropins used, embryologic variables (number of oocytes retrieved, number of suitable oocytes retrieved, fertilization rate, and rate of top-quality embryos), and clinical outcomes (miscarriage rate and live birth rate).

RESULTS

Overall, 630 women were randomized 2 to 12 weeks before the initiation of the in vitro fertilization cycle to receive either a single dose of 600,000 IU of vitamin D₃ (n=308) or placebo (n=322). Interestingly, 113 (37%) and 130 (40%) women achieved a clinical pregnancy in the treatment and placebo groups, respectively (P=.37). The risk ratio of clinical pregnancy in women receiving vitamin D₃ was 0.91 (95% confidence interval, 0.75-1.11). Compared with the placebo, vitamin D₃ supplementation did not improve the rate of clinical pregnancy. Exploratory subgroup analyses for body mass index, age, indication to in vitro fertilization, ovarian reserve, interval between drug administration and initiation of the cycle, and basal levels of 25-hydroxyvitamin D failed to highlight any clinical situation that could benefit from the supplementation.

CONCLUSION

In women with normal weight with preserved ovarian reserve and low vitamin D levels undergoing in vitro fertilization cycles, a single oral dose of 600,000 IU of vitamin D₃ did not improve the rate of clinical pregnancy. Although the findings do not support the use of vitamin D₃ supplementation to improve in vitro fertilization success rates, further studies are required to rule out milder but potentially interesting benefits and explore the effectiveness of alternative modalities of supplementation.

Basal Vitamin D Status and Supplement Dose Are Primary Contributors to Maternal 25-Hydroxyvitamin D Response to Prenatal and Postpartum Cholecalciferol Supplementation

BACKGROUND

Variability in the 25-hydroxyvitamin D [25(OH)D] response to prenatal and postpartum vitamin D supplementation is an important consideration for establishing vitamin D deficiency prevention regimens.

OBJECTIVES

We aimed to examine interindividual variation in maternal and infant 25(OH)D following maternal vitamin D supplementation.

METHODS

In a randomized trial of maternal vitamin D supplementation (Maternal Vitamin D for Infant Growth Trial), healthy pregnant women (n = 1300) received a prenatal cholecalciferol (vitamin D-3) dose of 0, 4200, 16,800, or 28,000 IU/wk from 17 to 24 wk of gestation followed by placebo to 6 mo postpartum. A fifth group received 28,000 IU cholecalciferol/wk both prenatally and postpartum. In a subset of participants, associations of 25(OH)D with hypothesized explanatory factors were estimated in women at delivery (n = 655) and 6 mo postpartum (n = 566), and in their infants at birth (n = 502) and 6 mo of age (n = 215). Base models included initial 25(OH)D and supplemental vitamin D dose. Multivariable models were extended to include other individual characteristics and specimen-related factors. The model coefficient of determination (R2) was used to express the percentage of total variance explained.

RESULTS

Supplemental vitamin D intake and initial 25(OH)D accounted for the majority of variance in maternal 25(OH)D at delivery and postpartum (R2 = 70% and 79%, respectively). Additional characteristics, including BMI, contributed negligibly to remaining variance (<5% increase in R2). Variance in neonatal 25(OH)D was explained mostly by maternal delivery 25(OH)D and prenatal vitamin D intake (R2 = 82%). Variance in 25(OH)D in later infancy could only partly be explained by numerous biological, sociodemographic, and laboratory-related characteristics, including feeding practices (R2 = 43%).

CONCLUSIONS

Presupplementation 25(OH)D and vitamin D supplemental dose are the major determinants of the response to maternal prenatal vitamin D intake. Vitamin D dosing regimens to prevent maternal and infant vitamin D deficiency should take into consideration the mean 25(OH)D concentration of the target population.

Vitamin D Nutritional Status of Chinese Pregnant Women, Comparing the Chinese National Nutrition Surveillance (CNHS) 2015-2017 with CNHS 2010-2012

Optimal vitamin D (vitD) status is beneficial for both pregnant women and their newborns. The aim of this study was to evaluate the vitamin D status of Chinese pregnant women in the latest China Nutrition and Health Surveillance (CNHS) 2015-2017, analyze the risk factors of vitamin D deficiency (VDD), and compare them with those in CNHS 2010-2012. Serum 25 hydroxyvitamin D (25(OH)D) was measured by ELISA method. City type, district, latitude, location, age, vitamin D supplements intake, education, marital status, annual family income, etc., were recorded. The median 25(OH)D concentration was 13.02 (10.17-17.01) ng/mL in 2015-2017, and 15.48 (11.89-20.09) ng/mL in 2010-2012. The vitamin D sufficient rate was only 12.57% in 2015-2017, comparing to 25.17% in 2010-2012. The risk factors of vitamin D inadequacy (25(OH)D < 20 ng/mL) in 2015-2017 were not exactly consistent with that in 2010-2012. The risk factors included season of spring (p < 0.0001) and winter (p < 0.001), subtropical (p < 0.001), median (p < 0.0001) and warm temperate zones (p < 0.0001), the western (p = 0.027) and the central areas (p = 0.041), while vitD supplements intake (p = 0.021) was a protective factor in pregnant women. In conclusion, vitD inadequacy is very common among Chinese pregnant women. We encourage pregnant women to take more effective sunlight and proper vitD supplements, especially for those from the subtropical, warm and medium temperate zones, the western and the central, and in the seasons of spring and winter.

Vitamin D Status and Factors Associated with Vitamin D Deficiency during the First Year of Life in Preterm Infants

We aimed to investigate the changes in vitamin D levels and factors associated with vitamin D deficiency (VDD) during the first year of life in Korean preterm infants. We enrolled 333 preterm infants who were born at Kyungpook National University Children’s Hospital between March 2013 and December 2019. 25-hydroxyvitamin D (25-OHD) levels and medical records were collected at birth, 6 months, and 12 months of age. The mean gestational age was 33.4 ± 2.3 weeks and mean 25-OHD levels at birth were 18.2 ± 13.5 ng/mL. The incidence of VDD was 82.8%, 30.6%, and 27.0% at birth, 6 months, and 12 months, respectively. The incidence of severe VDD (25-OHD < 10 ng/mL) was 31.5%, 1.5%, and 0%, at birth, 6 months, and 12 months, respectively. Among infants with severe VDD, the deficiency persisted in 49.6% at 6 months, and 35.3% at 12 months. The strongest predictor of VDD during follow-up was 25-OHD concentration at birth. Vitamin D supplementation at 400 IU/day did not affect vitamin D levels during the first year of life. Therefore, it is important to prevent neonatal VDD through maternal vitamin D supplementation during pregnancy. Further research is needed to determine the optimal vitamin D supplementation dose for Korean preterm infants.

Effects of vitamin and mineral supplementation during pregnancy on maternal, birth, child health and development outcomes in low- and middle-income countries: A systematic review

Background

Almost two billion people who are deficient in vitamins and minerals are women and children in low- and middle-income countries (LMIC). These deficiencies are worsened during pregnancy due to increased energy and nutritional demands, causing adverse outcomes in mother and child. To reduce micronutrient deficiencies, several strategies have been implemented, including diet diversification, large-scale and targeted fortification, staple crop bio-fortification and micronutrient supplementation.

Objectives

To evaluate and summarize the available evidence on the effects of micronutrient supplementation during pregnancy in LMIC on maternal, fetal, child health and child development outcomes. This review will assess the impact of single micronutrient supplementation (calcium, vitamin A, iron, vitamin D, iodine, zinc, vitamin B12), iron-folic acid (IFA) supplementation, multiple micronutrient (MMN) supplementation, and lipid-based nutrient supplementation (LNS) during pregnancy.

Search Methods

We searched papers published from 1995 to 31 October 2019 (related programmes and good quality studies pre-1995 were limited) in CAB Abstracts, CINAHL, Cochrane Central Register of Controlled Trials, Embase, International Initiative for Impact Evaluations, LILACS, Medline, POPLINE, Web of Science, WHOLIS, ProQuest Dissertations & Theses Global, R4D, WHO International Clinical Trials Registry Platform. Non-indexed grey literature searches were conducted using Google, Google Scholar, and web pages of key international nutrition agencies.

Selection Criteria

We included randomized controlled trials (individual and cluster-randomized) and quasi-experimental studies that evaluated micronutrient supplementation in healthy, pregnant women of any age and parity living in a LMIC. LMIC were defined by the World Bank Group at the time of the search for this review. While the aim was to include healthy pregnant women, it is likely that these populations had one or more micronutrient deficiencies at baseline; women were not excluded on this basis.

Data Collection and Analysis

Two authors independently assessed studies for inclusion and risk of bias, and conducted data extraction. Data were matched to check for accuracy. Quality of evidence was assessed using the GRADE approach.

Main Results

A total of 314 papers across 72 studies (451,723 women) were eligible for inclusion, of which 64 studies (439,649 women) contributed to meta-analyses. Seven studies assessed iron-folic acid (IFA) supplementation versus folic acid; 34 studies assessed MMN vs. IFA; 4 studies assessed LNS vs. MMN; 13 evaluated iron; 13 assessed zinc; 9 evaluated vitamin A; 11 assessed vitamin D; and 6 assessed calcium. Several studies were eligible for inclusion in multiple types of supplementation. IFA compared to folic acid showed a large and significant (48%) reduction in the risk of maternal anaemia (average risk ratio (RR) 0.52, 95% CI 0.41 to 0.66; studies = 5; participants = 15,540; moderate-quality evidence). As well, IFA supplementation demonstrated a smaller but significant, 12% reduction in risk of low birthweight (LBW) babies (average RR 0.88, 95% CI 0.78 to 0.99; studies = 4; participants = 17,257; high-quality evidence). MMN supplementation was defined as any supplement that contained at least 3 micronutrients. Post-hoc analyses were conducted, where possible, comparing the differences in effect of MMN with 4+ components and MMN with 3 or 4 components. When compared to iron with or without FA, MMN supplementation reduced the risk of LBW by 15% (average RR 0.85, 95% CI 0.77 to 0.93; studies = 28; participants = 79,972); this effect was greater in MMN with >4 micronutrients (average RR 0.79, 95% CI 0.71 to 0.88; studies = 19; participants = 68,138 versus average RR 1.01, 95% CI 0.92 to 1.11; studies = 9; participants = 11,834). There was a small and significant reduction in the risk of stillbirths (average RR 0.91; 95% CI 0.86 to 0.98; studies = 22; participants = 96,772) and a small and significant effect on the risk of small-for-gestational age (SGA) (average RR 0.93; 95% CI 0.88 to 0.98; studies = 19; participants = 52,965). For stillbirths and SGA, the effects were greater among those provided MMN with 4+ micronutrients. Children whose mothers had been supplemented with MMN, compared to IFA, demonstrated a 16% reduced risk of diarrhea (average RR 0.84; 95% CI 0.76 to 0.92; studies = 4; participants = 3,142). LNS supplementation, compared to MMN, made no difference to any outcome; however, the evidence is limited. Iron supplementation, when compared to no iron or placebo, showed a large and significant effect on maternal anaemia, a reduction of 47% (average RR 0.53, 95% CI 0.43 to 0.65; studies = 6; participants = 15,737; moderate-quality evidence) and a small and significant effect on LBW (average RR 0.88, 95% CI 0.78 to 0.99; studies = 4; participants = 17,257; high-quality evidence). Zinc and vitamin A supplementation, each both compared to placebo, had no impact on any outcome examined with the exception of potentially improving serum/plasma zinc (mean difference (MD) 0.43 umol/L; 95% CI -0.04 to 0.89; studies = 5; participants = 1,202) and serum/plasma retinol (MD 0.13 umol/L; 95% CI -0.03 to 0.30; studies = 6; participants = 1,654), respectively. When compared to placebo, vitamin D supplementation may have reduced the risk of preterm births (average RR 0.64; 95% CI 0.40 to 1.04; studies = 7; participants = 1,262), though the upper CI just crosses the line of no effect. Similarly, calcium supplementation versus placebo may have improved rates of pre-eclampsia/eclampsia (average RR 0.45; 95% CI 0.19 to 1.06; studies = 4; participants = 9,616), though the upper CI just crosses 1.

Authors' Conclusions

The findings suggest that MMN and vitamin supplementation improve maternal and child health outcomes, including maternal anaemia, LBW, preterm birth, SGA, stillbirths, micronutrient deficiencies, and morbidities, including pre-eclampsia/eclampsia and diarrhea among children. MMN supplementation demonstrated a beneficial impact on the most number of outcomes. In addition, MMN with >4 micronutrients appeared to be more impactful than MMN with only 3 or 4 micronutrients included in the tablet. Very few studies conducted longitudinal analysis on longer-term health outcomes for the child, such as anthropometric measures and developmental outcomes; this may be an important area for future research. This review may provide some basis to guide continual discourse around replacing IFA supplementation with MMN along with the use of single micronutrient supplementation programs for specific outcomes.

Associations between maternal circulating 25-hydroxyvitamin D concentration and birth outcomes-Mode of delivery and episiotomy rate: A prospective cohort study

AIM

The objective of this study was to evaluate associations between maternal concentrations of 25-hydroxyvitamin D (25(OHD)) and birth outcomes: mode of delivery and episiotomy rate.

DESIGN AND METHODS

One hundred and seventeen pregnant women were enrolled in an observational, longitudinal, prospective cohort study. Multivariable linear regression analyses were performed to assess relationships between maternal 25(OHD) concentrations and mode of delivery. To account for systematic temporal variation in 25(OHD), a cosinor model to the data was fitted.

RESULTS

No significant statistical associations were found between adjusted maternal 25(OHD) concentrations and risk of eutocic vaginal delivery, instrumented delivery (OR 1.05 [95% CI: 0.97-1.13]), primary Caesarean section (OR 0.99 [95% CI: 0.88-1.11]) or Caesarean section for any other causes (OR 1.04 [95% CI: 0.95-1.14]). High 25(OHD) levels tended to show a protective effect on performance of episiotomy, without reaching statistical significance (OR 0.36 [95% CI: 0.09, 1.37]).

Iron, iodine and vitamin D deficiencies during pregnancy: epidemiology, risk factors and developmental impacts

Micronutrient deficiency persists throughout the world, and although the burden is higher in low-resource settings, it is also prevalent in wealthy countries, a phenomenon termed 'hidden hunger'. Due to their high requirements for vitamins and minerals relative to their energy intake, young women and children are particularly vulnerable to hidden hunger. As they share several risk factors and impact on overlapping outcomes, we consider how deficiency of iron, iodine and vitamin D can have profound impacts on perinatal health and infant development. We review the epidemiology of these micronutrient deficiencies during pregnancy, including social, environmental and dietary risk factors. We identify the main challenges in defining nutritional status of these nutrients using validated diagnostic criteria linked with meaningful clinical outcomes. Public health strategies are urgently required to improve the overall health and nutritional status of women of reproductive age. Obesity prevention and early detection of malnutrition with standardised screening methods would detect pregnant women at increased risk of iron deficiency. Development of sensitive, individual biomarkers of iodine status is required to protect maternal health and fetal/infant brain development. Risk assessments of vitamin D requirements during pregnancy need to be revisited from the perspective of fetal and neonatal requirements. International consensus on standardised approaches to micronutrient assessment, analysis and reporting as well as sensitive, clinically validated infant and child neuro-behavioural outcomes will enable progression of useful observational and intervention studies.

Hormonal regulation of biomineralization

Biomineralization is the process by which organisms produce mineralized tissues. This crucial process makes possible the rigidity and flexibility that the skeleton needs for ambulation and protection of vital organs, and the hardness that teeth require to tear and grind food. The skeleton also serves as a source of mineral in times of short supply, and the intestines absorb and the kidneys reclaim or excrete minerals as needed. This Review focuses on physiological and pathological aspects of the hormonal regulation of biomineralization. We discuss the roles of calcium and inorganic phosphate, dietary intake of minerals and the delicate balance between activators and inhibitors of mineralization. We also highlight the importance of tight regulation of serum concentrations of calcium and phosphate, and the major regulators of biomineralization: parathyroid hormone (PTH), the vitamin D system, vitamin K, fibroblast growth factor 23 (FGF23) and phosphatase enzymes. Finally, we summarize how developmental stresses in the fetus and neonate, and in the mother during pregnancy and lactation, invoke alternative hormonal regulatory pathways to control mineral delivery, skeletal metabolism and biomineralization.

The importance of maternal pregnancy vitamin D for offspring bone health: learnings from the MAVIDOS trial

Optimisation of skeletal mineralisation in childhood is important to reduce childhood fracture and the long-term risk of osteoporosis and fracture in later life. One approach to achieving this is antenatal vitamin D supplementation. The Maternal Vitamin D Osteoporosis Study is a randomised placebo-controlled trial, the aim of which was to assess the effect of antenatal vitamin D supplementation (1000 IU/day cholecalciferol) on offspring bone mass at birth. The study has since extended the follow up into childhood and diversified to assess demographic, lifestyle and genetic factors that determine the biochemical response to antenatal vitamin D supplementation, and to understand the mechanisms underpinning the effects of vitamin D supplementation on offspring bone development, including epigenetics. The demonstration of positive effects of maternal pregnancy vitamin D supplementation on offspring bone development and the delineation of underlying biological mechanisms inform clinical care and future public-health policies.

Maternal and fetal vitamin D and their roles in mineral homeostasis and fetal bone development

During pregnancy, female physiology adapts to meet the additional mineral demands of the developing fetus. Meanwhile, the fetus actively transports minerals across the placenta and maintains high circulating levels to mineralize the rapidly developing skeleton. Most of this mineral is accreted during the last trimester, including 30 g of calcium, 20 g of phosphate and 0.8 g of magnesium. Given the dependence of calcium homeostasis on vitamin D and calcitriol in the adult and child, it may be expected that vitamin D sufficiency would be even more critical during pregnancy and fetal development. However, the pregnant mother and fetus appear to meet their mineral needs independent of vitamin D. Adaptations in maternal mineral and bone metabolism during pregnancy appear to be invoked independent of maternal vitamin D, while fetal mineral metabolism and skeletal development appear to be protected from vitamin D deficiency and genetic disorders of vitamin D physiology. This review discusses key data from both animal models and human studies to address our current knowledge on the role of vitamin D and calcitriol during pregnancy and fetal development.