Association between maternal plasma ferritin concentration, iron supplement use, and the risk of gestational diabetes: a prospective cohort study

Maternal Iron Levels and Association With Gestational Diabetes: A Systematic Review and Meta-Analysis

Background: This systematic review aimed to assess the association of iron level with gestational diabetes mellitus (GDM) risk. Methods: The relevant articles published between January 1, 1995 and January 17, 2023 were identified through a systematic literature search. This study used random effects to summarize the relative risks (RRs) 95% confidence intervals (CIs) of GDM risk and standardized mean differences. This study investigated the association of ferritin exposure with GDM combined with dose-response analysis and explored both linear and nonlinear trends. Results: This meta-analysis selected 30 studies with serum ferritin (SF), 18 studies with serum iron (SI), 4 studies with serum transferrin receptor (sTfR), 5 studies with total iron binding capacity (TIBC), and 4 studies with transferrin (TRF). The summarized RRs comparing persons with the highest concentration categories of SF with the lowest concentration categories of SF with an unadjusted odds ratio were 2.05 (1.67-2.53; I 2 = 62.8%, p < 0.001, z = 6.76, p < 0.001) and with an adjusted odds ratio were 1.82 (1.54-2.14; I 2 = 12.9%, p=0.312, z = 7.21, p < 0.001). Linear dose-response showed that an increase in SF of 5 μg/L increased the risk of GDM by 2.66% (1.026 [95% CI: 1.017, 1.036], n = 5). The nonlinear dose-response relationship also indicates that the increased SF is consistently associated with an increasing risk of GDM. Conclusion: High ferritin, high iron levels, and low TIBC are associated with an increased risk of GDM.

A prospective study of early pregnancy metal concentrations and gestational diabetes mellitus based on a birth cohort in Northwest China

BACKGROUND

Exposure to metals during early pregnancy may affect maternal glucose metabolism. We were aimed to assess the associations between early pregnancy whole blood concentrations of copper (Cu), zinc (Zn), calcium (Ca), iron (Fe), and magnesium (Mg) with GDM later in the second trimester among pregnant women in Northwest China.

METHODS

This study included 5478 first-trimester pregnant women who participated in the birth cohort of the Northwest Women's and Children's Hospital between July 2018 and December 2023. Metal concentrations, basic demographic characteristics, lifestyle and behavior patterns were collected. An oral glucose tolerance test was performed in the second trimester. A generalized linear model was used to analyze the effects of metal concentrations on GDM. A two-piecewise regression model was adopted to examine the threshold effect and find out the turning point. Weighted Quantile Sum (WQS) regression was conducted using a dataset randomly split into training and validation sets at a 4:6 ratio to investigate the association between metal mixtures and GDM.

RESULTS

Compared to the lowest tertile, the middle (RR = 0.82, 95%CI = 0.71, 0.95) and highest (RR = 0.84, 95%CI = 0.73, 0.97) tertiles of Ca concentrations could decrease the risk of GDM. However, the highest tertile of Cu concentration could increase the risk of GDM (RR = 1.18, 95%CI = 1.01, 1.39). Additionally, a non-linear relationship between Ca concentration with GDM and FPG was observed. The risk of GDM (RR = 0.08, 95%CI: 0.02, 0.31) and FPG (β=-0.56, 95%CI: -0.99, -0.12) decreased with 1 unit increase in ln-transformed Ca concentration below the turning point. However, the WQS index of maternal mixed metals was not correlated with the incidence of GDM (RR = 1.08, 95%CI = 0.98, 1.19).

CONCLUSIONS

Higher Cu concentration during early pregnancy may increase the risk of GDM in mothers. Increased Ca concentration may reduce the risk of GDM and lower the concentration of FPG below the turning point. Our findings could provide an early marker for potentially modifiable risk factors associated with maternal glucose dysregulation during pregnancy.

A retrospective study of the correlation between high serum ferritin levels and the risk of gestational diabetes mellitus in midpregnant women

Aims

Gestational diabetes mellitus (GDM) is any degree of glucose intolerance with onset or first detection during pregnancy, with an inconsistent association with serum ferritin (SF). We aimed to ascertain the relationship between SF and the risk of GDM in mid-pregnancy and provide evidence for implementing clinical individualized and reasonable iron supplementation regimens.

Methods

A retrospective study was conducted to investigate 1,052 pregnant women at 24-28 weeks of gestation who were examined in the obstetrics department of The Fourth Hospital of Shijiazhuang from January 2019 to December 2021. Questionnaires were used to obtain the general information. The levels of serum ferritin (SF), serum calcium, glycated haemoglobin (HbA1c) and Oral-Glucose-Tolerance-Test (OGTT) were reviewed. The GDM was diagnosed by glucose tests. Multivariate logistic regression was used to determine the relationship between serum ferritin and GDM.

Results

Compared to the non-GDM group, the GDM group had significantly higher level of SF (13.95 (8.59-23.65) ng/mL vs. 12.11 (7.27-19.86) ng/mL, (p = 0.012)). While SF levels positively correlated with 1-hour plasma glucose levels (PG1H) (r = 0.061, p = 0.047), there was a negative correlation between SF and HbA1c levels (r =  - 0.078, p = 0.011). The risk of GDM with higher levels of SF was increased (1.010 (95% CI [1.001-1.020], p = 0.025)). In the univariate logistic regression model, the risk of GDM in pregnant women with high ferritin levels was 1.010 (95% CI [1.001-1.020], p = 0.025). After adjustment for age and pre-pregnancy body mass index (BMI), the risk of GDM was significantly increased by 44% and 42% respectively (adjusted odds ratio (AOR) = 1.440, 95% CI [1.025-2.023], p = 0.035), AOR = 1.420 (95% CI [1.011-1.995], p = 0.043). After multivariate adjustment for age and pre-pregnancy BMI, the results were moderately revised (AOR = 1.427, 95%CI [1.013-2.008], p = 0.042).

Conclusions

Elevated SF levels of mid-pregnancy was associated with risk of GDM, which may guide the implementation of pregnancy-specific supplementation to some extent with the support of further clinical trials.

Serum Ferritin Levels in Pregnancy and Their Association with Gestational Diabetes Mellitus: A Prospective Longitudinal Study

Objective

Elevated serum ferritin (SF) levels are associated with oxidative stress (OS) and systemic inflammation in various disorders. However, the changes in SF levels during pregnancy and their relationship with gestational diabetes mellitus (GDM) and blood glucose levels are not well understood.

Methods

This prospective longitudinal study included 390 participants (130 GDM cases and 260 controls) during early pregnancy. We measured SF levels in the1st, 2nd, and 3rd trimesters, as well as plasma malondialdehyde (MDA) and C-reactive protein (CRP) in the 1st trimester, blood glucose levels in the oral glucose tolerance test (OGTT), and glycosylated hemoglobin (HbA1c) in the 2nd trimester. We used Spearman's rank correlation to estimate the association between SF, OS, inflammation and glucose levels. Logistic regression analysis was performed to estimate the OR of GDM associated with SF. Multiple stepwise regression models were used to assess the relationship between glucose levels and the risk factors.

Results

SF levels decreased with increasing gestation in the study population. Compared to controls, GDM patients had significantly higher levels of SF (1st and 2nd trimesters), MDA, CRP, and HbA1c. SF was positively correlated with MDA and fasting plasma glucose (FPG). Elevated SF levels during early pregnancy were significantly associated with increased GDM risks (OR = 2.024, 95% CI: 1.076 - 3.807). The explanatory variables that contributed to increased glucose levels were SF, MDA, body mass index (BMI), maternal age, and family history of diabetes.

Conclusion

SF is significantly associated with GDM and may be a potential biomarker for GDM in early pregnancy.

The association between serum ferritin levels and the risk of gestational diabetes mellitus: a prospective cohort study

BACKGROUND

The relationship between serum ferritin levels and the risk of gestational diabetes mellitus (GDM) remains unclear. This study aimed to investigate the association between serum ferritin levels and the incidence of GDM.

METHODS

We conducted a prospective cohort study involving 10,871 pregnant women from the China Birth Cohort Study. Serum ferritin levels were measured using the direct chemiluminescence method in the first and second trimesters. Baseline serum ferritin levels were categorized into five groups according to quintiles in the first trimester, and trimester-specific median values were used to divide serum ferritin levels into four subgroups. GDM was determined by a 75 g oral glucose tolerance test at 24-28 weeks of gestation. Multivariate modified Poisson regression was performed to estimate the independent relationship between serum ferritin levels and the incident GDM.

RESULTS

The median serum ferritin level in the first trimester was 57.7 ng/mL, and 13.5% of participants developed GDM. After multivariate adjustment, the RRs and 95% CIs for incident GDM across baseline serum-ferritin quintiles were 1.099 (0.940-1.285), 1.228 (1.055-1.430), 1.186 (1.018-1.383) and 1.179 (1.017-1.367), respectively. Furthermore, participants with low serum ferritin levels in the first trimester that increased to high levels in the second trimester (RR = 1.376, 95% CI: 1.169-1.612) and those with consistently high serum ferritin levels in the first and second trimesters (RR = 1.351, 95% CI: 1.185-1.541) had a significantly increased risk of GDM.

CONCLUSIONS

Changes in serum ferritin levels are independent risk factors for GDM. These findings underscore the importance of maintaining iron metabolism at an appropriate level during early to mid-pregnancy to reduce the risk of developing GDM.

Association of iron homeostasis-related gene polymorphisms with pregnancy and neonatal outcomes in patients with gestational diabetes mellitus

OBJECTIVE

The purpose of this study was to assess associations between iron homeostasis-related gene polymorphisms and gestational diabetes mellitus (GDM), adverse pregnancy outcomes, and neonatal outcomes.

METHODS

In total, 138 patients with GDM and 74 normal pregnancy controls were recruited. Time-of-flight mass spectrometry was used to genotype single-nucleotide polymorphisms (H63D rs1799945, TMPRSS6 rs855791, GDF15 rs1059369, rs4808793, BMP2 rs173107, C282Y rs3811647, rs1800562, rs269853, TF rs8177240, TFR2 rs7385804, FADS2 rs174577, and CUBN rs10904850) in 12 candidate genes related to iron homeostasis. Adverse pregnancy outcomes and neonatal health data were collected. Differences in genotype distributions and allele frequencies between patients and controls as well as their correlations with clinical factors were assessed. Additionally, associations between genotype, haemoglobin levels, and ferritin levels were evaluated.

RESULTS

Pregnant women carrying the GDF15 rs4808793 allele (C) or TMPRSS6 rs855791 homozygous mutation (GG) had a significantly higher risk of GDM than that in the control group (p < 0.05). In patients with GDM, the BMP2 rs173107 heterozygous mutation (AC) was associated with significantly higher haemoglobin levels in late pregnancy compared with those for wild-type (AA) BMP2 (p < 0.05). Furthermore, in patients with GDM, the FADS2 rs174577 heterozygous mutation (AC) was associated with a significantly reduced risk of preterm birth (p < 0.05), the H63D rs1799945 heterozygous mutation (CG) was associated with a significantly increased risk of adverse neonatal outcomes (p < 0.05), TFR2 rs7385804 was associated a significantly reduced probability of caesarean section (p < 0.05), and the G mutation in TMPRSS6 rs855791 was related to a significantly increased probability of caesarean section (p < 0.05).

CONCLUSIONS

These results suggest that polymorphisms in genes related to iron metabolism could potentially impact pregnancy and neonatal outcomes in patients with GDM. Large-scale studies are needed to further clarify the relationship between these polymorphisms and susceptibility to GDM.

Associations of maternal serum concentration of iron-related indicators with gestational diabetes mellitus in Chinese: A pilot prospective cohort study

BACKGROUND

We aimed to provide a comprehensive understanding of the associations between iron metabolism and gestational diabetes mellitus (GDM) by examining multiple iron-related indicators.

METHODS

We conducted a prospective study involving 907 Chinese pregnant women. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum concentrations of iron-related indicators during the first trimester (≤ 14 weeks of gestation). GDM outcomes were measured through oral glucose tolerance tests (OGTT) conducted between weeks 24 and 28 of gestation.

RESULTS

Subjects with iron-related indicators below the 10th percentile (except for serum iron and soluble transferrin receptor) had a higher risk of GDM compared to normal subjects (10th-90th percentiles). The ORs (95 %CI; p-value) were 1.88 (1.10, 3.20; P=0.020) for ferritin, 1.88 (1.10, 3.19; P=0.020) for hepcidin. Higher levels of ferritin (> 90th percentile) were associated with a higher risk of abnormal fasting blood glucose, while lower levels (< 10th percentile) of ferritin, hepcidin, and transferrin were associated with a higher risk of one-hour postprandial glucose ≥ 8.6 mmol/L in the OGTT.

CONCLUSIONS

Lower levels (< 10th percentiles) of several iron-related indicators (ferritin, hepcidin, and transferrin) were associated with a higher risk of GDM and abnormal blood glucose compared to normal subjects.

Associations of maternal serum ferritin levels across gestation with gestational diabetes mellitus: A longitudinal cohort study

BACKGROUND

The longitudinal changes in maternal serum ferritin (SF) levels across gestation, which indirectly reflect iron supplementation, have not been extensively investigated in relation to gestational diabetes mellitus (GDM).

METHODS

We conducted a retrospective cohort study at a tertiary maternal hospital in Shanghai. Women with SF concentration measurements at 8.0-13.6 weeks' gestation (GW), 29.0-31.6 GW, and an oral glucose tolerance test (OGTT) at 24-28 GW were included. We utilized logistic regression analysis to assess GDM association with maternal SF levels and longitudinal changes.

RESULTS

The study included 17 560 women, with 2160 (12.3%) participants diagnosed with GDM. Adjusted odds ratios (ORs) (95% confidence intervals [CIs]) for GDM across increasing quartiles of SF concentrations at 8.0-13.6 GW were 1.00 (reference), 1.139 (95% CI: 1.012-1.283), 1.093 (95% CI: 0.969-1.233), and 1.248 (95% CI: 1.111-1.403). Similarly, at 29.0-31.6 GW, increasing quartiles of SF concentrations were associated with higher adjusted ORs for GDM: 1.00 (reference), 1.165 (95% CI: 1.029-1.320), 1.335 (95% CI: 1.184-1.505), and 1.428 (95% CI: 1.268-1.607). Pregnant women with higher SF levels (upper 25th percentile) at 8.0-13.6 GW had a reduced GDM risk if their SF levels decreased to the lower 25th percentile at 29.0-31.6 GW. Conversely, the subgroup with higher SF levels (upper 25th percentile) at both time points had the highest incidence rate of GDM (15.3%, 1.235 [95% CI: 1.087-1.404]).

CONCLUSIONS

Maternal SF levels independently and positively associated with GDM risk during early and late gestational stages. Considering the increased GDM risk, routine iron supplementation for iron-replete women is questionable.

Dietary management of gestational diabetes: A review

Gestational diabetes mellitus (GDM) is a common condition in pregnant women that can affect the health of both the mother and the fetus. A healthy diet reduces the risk of GDM, while on the contrary, an unhealthy diet can increase the risk of developing GDM. Dietary interventions remain an important way to control GDM at this time. However, real-life diets are complex and varied, and the effect of these diets on gestational diabetes is unknown. This article summarizes research related to dietary control of GDM. Hopefully, this will help with dietary interventions for people with GDM.

EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, Bohn T, Castenmiller J, de Henauw S, Hirsch‐Ernst K, Knutsen HK, Maciuk A, Mangelsdorf I, McArdle HJ, Pentieva K, Siani A, Thies F, Tsabouri S, Vinceti M, Aggett P, Fairweather‐Tait S, de Sesmaisons Lecarré A, Fabiani L, Karavasiloglou N, Saad RM, Sofroniou A, Titz A, Naska A. Scientific opinion on the tolerable upper intake level for iron

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the tolerable upper intake level (UL) for iron. Systematic reviews were conducted to identify evidence regarding high iron intakes and risk of chronic diseases, adverse gastrointestinal effects and adverse effects of iron supplementation in infancy, young childhood and pregnancy. It is established that systemic iron overload leads to organ toxicity, but no UL could be established. The only indicator for which a dose-response could be established was black stools, which reflect the presence of large amounts of unabsorbed iron in the gut. This is a conservative endpoint among the chain of events that may lead to systemic iron overload but is not adverse per se. Based on interventions in which black stools did not occur at supplemental iron intakes of 20-25 mg/day (added to a background intake of 15 mg/day), a safe level of intake for iron of 40 mg/day for adults (including pregnant and lactating women) was established. Using allometric scaling (body weight0.75), this value was scaled down to children and adolescents and safe levels of intakes between 10 mg/day (1-3 years) and 35 mg/day (15-17 years) were derived. For infants 7-11 months of age who have a higher iron requirement than young children, allometric scaling was applied to the supplemental iron intakes (i.e. 25 mg/day) and resulted in a safe level of supplemental iron intake of 5 mg/day. This value was extended to 4-6 month-old infants and refers to iron intakes from fortified foods and food supplements, not from infant and follow-on formulae. The application of the safe level of intake is more limited than a UL because the intake level at which the risk of adverse effects starts to increase is not defined.

Ferritin and iron supplements in gestational diabetes mellitus: less or more?

Iron metabolism has been found to be closely related to gestational diabetes mellitus (GDM). Excessive ferritin levels were shown to be related to an increased risk of GDM because of iron overload which may lead to insulin resistance and β-cell injury by enhancing oxidative stress and inflammatory responses. On the contrary, insufficient ferritin levels can cause a number of obstetric complications, such as high incidence rates of anaemia and gestational hypertension. Therefore, high or low ferritin levels may have adverse effects on the mother and the foetus, putting clinicians in a dilemma when giving pregnant women iron supplements. This also explains why there have been more conflicting findings in the studies on dietary or oral iron supplementation during pregnancy. Hence, there is an urgent need for more evidence and strategies for appropriate recommendations for ferritin levels and iron supplementation during pregnancy to prevent iron insufficiency without causing iron overload and increasing the risk of GDM. Therefore, we gave an updated review on the association of GDM with ferritin metabolism, ferritin levels and iron supplementation based on the summary of the latest research.

Remnant Cholesterol Is Associated With Gestational Diabetes Mellitus: A Cohort Study

CONTEXT

The association between remnant cholesterol (RC) and gestational diabetes mellitus (GDM) risk is unclear.

OBJECTIVE

This study investigated the association between RC and GDM.

METHODS

We used data from the Tongji Maternal and Child Health Cohort, a prospective cohort study in China. Fasting lipid concentrations were measured around 16 weeks' gestation. RC was calculated as total cholesterol minus low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. GDM was diagnosed by a 75-g oral glucose tolerance test at 24 to 28 weeks' gestation. Log-Poisson regression models were performed to estimate relative risks (RRs) of GDM across quartiles of RC levels and triglyceride (TG) levels after adjustment for potential confounders. TG and RC were mutually adjusted.

RESULTS

Among 2528 women, 256 (10.1%) developed GDM. The adjusted RRs (95% CIs) for GDM across increasing quartiles of RC were 1.00 (reference), 1.35 (0.91, 1.99), 1.68 (1.16, 2.45), and 1.73 (1.19, 2.50), respectively. Compared to pregnant women without 3 risk indicators (TG <2.08 mmol/L, RC <0.40 mmol/L, and pre-BMI <24.0 kg/m2), the risk of GDM was elevated in those with normal pre-BMI but high RC (aRR: 1.54; 95% CI: 1.08, 2.19) or high TG (aRR: 2.15; 95% CI: 1.33, 3.49). For those with all 3 risk indicators, the risk of GDM was the highest (aRR: 4.80; 95% CI: 3.20, 7.18).

CONCLUSION

Elevated RC levels were associated with the increased risk of GDM and independent of traditional risk factors. Pregnant women with high pre-BMI, high TG, and high RC were at greatly increased risk of GDM.

Association of elevated mid-pregnancy maternal plasma ferritin concentrations and triglyceride concentrations with the risk of gestational diabetes mellitus: A prospective cohort study

OBJECTIVE

Ferritin levels are well known to be associated with gestational diabetes mellitus (GDM). However, the association of the combination of ferritin and triglyceride (TG) levels in early mid-pregnancy with GDM has not been studied in depth. We investigated the independent and combined relationships of plasma ferritin and TG concentrations with the risk of GDM as well as the mediation effect of TG on ferritin.

METHODS

We analysed 2071 pregnant women from the Tongji Maternal and Child Health Cohort who had their plasma ferritin and TG concentrations measured at 11-20 weeks of gestation. Associations between ferritin and TG concentrations and GDM risk were estimated using multivariable logistic regression models. Youden's index was calculated to find the cut-off values of ferritin and TG by ROC curve analysis. The mediation effect of the TG concentration on the ferritin level with GDM risk was explored by a mediation analysis.

RESULTS

A total of 264 (12.3%) participants developed GDM. The median and IQR of ferritin was 53.9 (30.5-92.7) ng/mL. After adjusting for potential confounders, the relative risks (RRs) and 95% confidence intervals of GDM were 2.19 (1.42, 3.39) for ferritin and 2.02 (1.37, 2.97) for TG. The adjusted RR for combination was 2.40 (1.62, 3.55). Moreover, we found that the TG concentration mediated 15.0% of the total effect of the ferritin concentration on the risk of GDM.

CONCLUSIONS

Women with a combination of both high plasma ferritin (˃55.7 ng/mL) and high TG (˃1.9 mmoL/L) were at the highest risk of GDM. Additionally, we have revealed for the first time that an elevated maternal TG concentration in early pregnancy mediates the relationship between ferritin concentration and GDM risk.

TRIAL REGISTRATION

This trial is registered at https://ClinicalTrials.gov as NCT03099837.

The associations of ferritin, serum lipid and plasma glucose levels across pregnancy in women with gestational diabetes mellitus and newborn birth weight

BACKGROUND

Women with gestational diabetes mellitus (GDM) are at greater risk of abnormal birth weight. Since the level of biochemical indicators could often affect the intrauterine growth and development of the fetus, it is of great practical significance to understand the changes of biochemical levels across pregnancy in women with GDM and to find out the indicators that play an important role in predicting birth weight.

METHODS

The data source of this study was from the Xi'an Longitudinal Mother-Child Cohort study (XAMC), in which women with GDM with normal and high pre-pregnancy body mass index (BMI) and their newborns between January 1^st and March 31^st in 2018 were included. The data of ferritin, serum lipid profile and fasting plasma glucose (FPG) of mothers in the three trimesters of pregnancy, as well as birth weight of newborns were all collected from medical records. Multiple linear regression and multivariate logistic regression analyses were used to explore the association of the biochemical indexes and birth weight. A P value < 0.05 was considered statistically significant.

RESULTS

A total of 782 mother-infant pairs were finally included and divided into normal weight group (NG) (n = 530, 67.8%) and overweight/obesity group (OG) (n = 252, 32.2%) according to maternal pre-pregnancy BMI. The level of ferritin in both NG and OG decreased during pregnancy (P for trend < 0.001 for all), whereas the levels of total cholesterol (TC), high density cholesterol (HDL-C), low density cholesterol (LDL-C) and triglycerides (TG) all showed an upward trend (P for trend < 0.05 for all). The levels of FPG in the two groups remained in a relatively stable during the whole pregnancy even though it was higher in OG during the 2^nd and 3^rd trimesters, whilst HbAlc levels in NG women increased (P for trend = 0.043) during pregnancy. Meanwhile, the risk of macrosomia and large-for-gestational-age (LGA) increased with the increase of FPG level (P for trend < 0.05). Multivariate logistic regression analyses results showed that only FPG level in the 3^rd trimester was correlated with birth weight, with birth weight increased by 44.9 g for each SD increase in FPG level.

CONCLUSION

Maternal FPG in the 3^rd trimester is an independent predictor of newborn birth weight, and a higher level of that is associated with an increased risk of macrosomia and LGA.

Longitudinal plasma magnesium status during pregnancy and the risk of gestational diabetes mellitus: a prospective cohort study

Emerging evidence has shown that magnesium (Mg) was associated with type 2 diabetes while few focused on abnormal glucose metabolism during pregnancy. The study is aimed at investigating the association between longitudinal changes in plasma Mg during pregnancy and subsequent risk of gestational diabetes (GDM) and exploring the possible influence of iron supplementation on the changes of plasma Mg levels. One thousand seven hundred fifty-six pregnant women from Tongji Maternal and Child Health Cohort (TMCHC) were involved. Blood samples were collected at gestational weeks 17.0 ± 0.9 and later 26.2 ± 1.4. Plasma Mg was measured by inductively coupled plasma mass spectrometry (ICP-MS) with decline rates calculated. Information on general characteristics and iron supplementation was collected by questionnaires. Oral glucose tolerance test (OGTT) was conducted at 24-28 gestational weeks to diagnose GDM. Poisson regression with robust error variance was used to estimate relative risks (RR) of GDM. Median concentrations of plasma Mg were 0.69 mmol/L and 0.63 mmol/L respectively at two collections. The prevalence of hypomagnesemia at the first collection was 73% and associated with a 1.59 (95%CI: 1.07, 2.37) fold risk of GDM. Adjusted RRs were 1.74 (95%CI: 1.06, 2.83) and 2.44 (95%CI: 1.54, 3.85) for women with hypomagnesemia and followed more tertile (T2 and T3 vs. T1) of Mg decrement. Iron supplementation above 30 mg/day was found associated with more Mg decrement (25.5% and 27.5% in T2 and T3 vs. 19.5% in T1). In conclusion, hypomagnesemia during pregnancy is prevalent and associated with increased GDM risk, especially in women followed by more plasma Mg decrement during pregnancy. High-dose iron supplementation may involve more plasma Mg decrement.

Role of ferroptosis in pregnancy related diseases and its therapeutic potential

Ferroptosis is a form of regulated cell death characterized by iron overload, overwhelming lipid peroxidation, and disruption of antioxidant systems. Emerging evidence suggests that ferroptosis is associated with pregnancy related diseases, such as spontaneous abortion, pre-eclampsia, gestational diabetes mellitus, intrahepatic cholestasis of pregnancy, and spontaneous preterm birth. According to these findings, inhibiting ferroptosis might be a potential option to treat pregnancy related diseases. This review summarizes the mechanisms and advances of ferroptosis, the pathogenic role of ferroptosis in pregnancy related diseases and the potential medicines for its treatment.

Correlation between high serum ferritin levels and adverse pregnancy outcomes in women with gestational diabetes mellitus

Aims

To explore the association between higher serum ferritin (SF) levels in mid-pregnancy and adverse pregnancy outcomes in gestational diabetes mellitus (GDM) pregnancies, then develop a predictive cut-off value that might effectively predict the risk of adverse pregnancy outcomes in future clinical.

Methods

The study involved 201 pregnant women with GDM. 201 gestational age and parity matched normoglycemic pregnant women were taken as control group. The differences in clinical data were compared by the Mann-Whitney U test and Chi-square tests. Multivariate logistic regression was used to determine the relationship between SF and GDM-relate adverse pregnancy outcomes. The predicted value of SF level was determined through receiver operating characteristic (ROC) curve analysis.

Results

SF level was significantly higher in women with GDM [16.10 (27.30-9.50) (ng/mL) vs. 12.04 (18.11-7.06) (ng/mL), (p < 0.001)]. Meanwhile, higher levels of SF were also discovered in GDM women with preeclampsia and neonatal hypoglycemia and respiratory distress (all p < 0.05). In the adjusted model, a positive association was shown between SF and preeclampsia [adjusted odds ratio (AOR) = 1.032, 95%CI = 1.004-1.060, p = 0.024], neonatal hypoglycemia [adjusted odds ratio (AOR) = 1.047, 95%CI = 1.022-1.072, p < 0.001] and respiratory distress outcomes (AOR = 1.034, 95%CI = 1.011-1.058, p = 0.004) respectively. The area under ROC curve (AUC) for prediction of preeclampsia by SF combined with serum calcium, age, pre-pregnancy BMI and gestational weight gain (GWG) was 0.658 (95% CI = 50.8-80.8%, p = 0.028) with the cut-off value of 24.45 ng/mL, and the sensitivity and specificity were 58.8.0% and 64.3%, respectively. To predict neonatal hypoglycemia, the clinical point value of SF was 27.43 ng/mL with AUC was 0.800, sensitivity and specificity was 90.5% and 68.0% respectively. Predicting neonatal respiratory distress, the AUC value of the SF level was 0.730, with a cut-off value of 27.37 ng/mL and the sensitivity and specificity were 52.0% and 86.5%, respectively.

Conclusions

Higher level of SF in mid-pregnancy was significantly associated with the risk of GDM and GDM-relate adverse pregnancy outcomes. Moreover, SF levels have moderate clinical value in predicting the adverse outcomes of maternal preeclampsia, neonatal hypoglycemia and respiratory distress.

Impact of iron supplementation on gestational diabetes mellitus: A literature review

Gestational diabetes mellitus (GDM) is a common complication of pregnancy, affecting 14% of pregnancies worldwide, and the prevention of pathological hyperglycaemia during pregnancy is meaningful for global public health. The role of iron supplementation in the progression of GDM has been of significant interest in recent years. Iron is a micronutrient that is vital during pregnancy; however, given the toxic properties of excess iron, it is probable that prophylactic iron supplementation will increase the risk of adverse pregnancy outcomes, including GDM. It is critical to clarify the effect of iron supplementation on the risk of GDM. Therefore, in this review, we comprehensively assess the role of iron in pregnancy. This review aimed to analyse the necessity of iron supplementation and maintenance of iron homeostasis during pregnancy, particularly reviewing the role and function of iron in beta cells and examining the mechanisms of excess iron contributing to the pathogenesis of GDM. Moreover, we aimed to discuss the association of haemoglobin and ferritin with GDM and identify priority areas for research.

Pregnancy thiamine and riboflavin intake and the risk of gestational diabetes mellitus: A prospective cohort study

BACKGROUND

Thiamine and riboflavin deficiencies exist to varying degrees worldwide, especially in developing countries. Evidence regarding the association between thiamine and riboflavin intake and gestational diabetes mellitus (GDM) is scarce.

OBJECTIVES

We aimed to evaluate the association of thiamine and riboflavin intake during pregnancy, including dietary source and supplementation, with GDM risk in a prospective cohort study.

METHODS

We included 3036 pregnant women (923 in the first trimester and 2113 in the second trimester) from the Tongji Birth Cohort. A validated semi-quantitative food frequency questionnaire and a lifestyle questionnaire were used to assess thiamine and riboflavin intake from dietary source and supplementation, respectively. GDM was diagnosed using the 75 g 2-h oral glucose tolerance test at 24-28 weeks of gestation. A modified Poisson regression or logistic regression model was used to evaluate the association between thiamine and riboflavin intake and GDM risk.

RESULTS

Dietary intake of thiamine and riboflavin was at low levels during pregnancy. In the fully adjusted model, compared with participants in quartile 1 (Q1), those who had more total thiamine and riboflavin intake had a lower risk of GDM during the first trimester [thiamine: Q2: RR: 0.58 (95% CI: 0.34, 0.98); Q3: RR: 0.45 (95% CI: 0.24, 0.84); Q4: RR: 0.35 (95% CI: 0.17, 0.72), P for trend = 0.002; riboflavin: Q2: RR: 0.63 (95% CI: 0.37, 1.09); Q3: RR: 0.45 (95% CI: 0.24, 0.87); Q4: RR: 0.39 (95% CI: 0.19, 0.79), P for trend = 0.006]. This association was also observed during the second trimester. Similar results were observed for the association between thiamine and riboflavin supplement use but not dietary intake and GDM risk.

CONCLUSIONS

Higher intake of thiamine and riboflavin during pregnancy is associated with a lower incidence of GDM. This trial was registered at http://www.chictr.org.cn as ChiCTR1800016908.

Is iron status associated with markers of non-communicable disease in adolescent Indian children?

BACKGROUND

High body iron status has been associated with non-communicable diseases (NCD) like diabetes (high fasting blood glucose, FBG), hypertension (HTN) or dyslipidaemia (high total cholesterol, TC) in adults, but this has not been examined in adolescent children. This is relevant to iron supplementation and food iron fortification programs that are directed at Indian children.

METHODS

The association of NCD with Serum Ferritin (SF) was examined using logistic additive models, adjusted for confounders such as age, body mass index, C-Reactive Protein, haemoglobin and sex, in adolescent (10-19 years old) participants of the Indian Comprehensive National Nutrition Survey. The interaction of these associations with wealth and co-existing prediabetes was also examined. A scenario analysis was also done to understand the impact of iron fortification of cereals on the prevalence NCD among adolescents.

RESULTS

The odds ratio (OR) of high FBG, HTN and TC were 1.05 (95% CI: 1.01-1.08), 1.02 (95% CI: 1.001-1.03) and 1.04 (95% CI: 1.01-1.06) respectively for every 10 µg/L increase in SF. The odds for high TC increased with co-existing prediabetes. The scenario analysis showed that providing 10 mg of iron/day by fortification could increase the prevalence of high FBG by 2-14% across states of India. Similar increments in HTN and TC can also be expected.

CONCLUSIONS

High SF is significantly associated with NCD in adolescents, dependent on wealth and co-existing prediabetes. This should be considered when enhancing iron intake in anaemia prevention programs, and the NCD relationship with body iron stores should be studied.

Iron Supplementation in Pregnancy and Risk of Gestational Diabetes: A Narrative Review

Pregnant women frequently supplement their diets with iron to treat any cryptic anemia, on the assumption that if anemia is not present, there will be no negative consequences. However, in women who are already iron-replete, it has been suggested that this can lead to iron overload and an increased risk of certain pregnancy complications. One such complication is gestational diabetes. Fourteen clinical trials, case-control or cohort studies (found using Pubmed/Scopus/Web of Science) have investigated links between iron supplementation in pregnancy and risk of gestational diabetes, several of them finding significant associations with increased risk. Potential mechanisms include increased oxidative stress leading to insulin resistance and inadequate compensatory insulin secretion. Current evidence suggests that dietary supplementation with iron in pregnancy may increase a pregnant woman's chance of developing gestational diabetes, although available evidence is somewhat contradictory, and the magnitude of any increased risk appears relatively small. Meta-analyses have suggested the presence of significant heterogeneity in results between studies, urging a degree of caution in interpreting these results. It is currently suggested that advice to pregnant women about whether to supplement their diets with iron or not should consider both their current iron status and their other established risk factors for gestational diabetes.

Association of low birthweight and small for gestational age with maternal ferritin levels: A retrospective cohort study in China

Background

Birthweight have profound impacts on health status throughout lifetime, however, the relationship between maternal ferritin level in pregnancy and birthweight of the newborn remains controversial.

Objective

This retrospective cohort research was to analyze the association between maternal ferritin levels during pregnancy with birthweight outcomes, primarily for low birthweight (LBW) and small for gestational age (SGA).

Methods

Newborns weighing lower than 2,500 grams were defined as LBW. SGA is defined as birthweight lower than the 10^th percentile of the distribution of newborns' birthweight of the same gestational age. Multivariable logistic regressions have been used to explore the association of maternal ferritin levels and birthweight related outcomes, in which the ferritin concentration was logarithm transformed in the model. We further used restricted cubic spline models to explore linear/non-linear dose–response manners of ferritin level and birthweight outcomes.

Results

A total of 3,566 pregnant women were included in the study. In the results of the present study, we observed that maternal ferritin levels were linearly associated with the risk of LBW (p-trend = 0.005) and SGA (p-trend = 0.04), with the adjusted odds ratios (ORs) of 1.78 (95% CI 1.37–2.32) for LBW and 1.87 (95% CI 1.38–2.54) for SGA with an increase in Ln-ferritin concentrations per unit. The adjusted ORs across quartiles of ferritin levels were 2.14 (95% CI 1.03–4.47) for Quartile 2, 3.13 (95% CI 1.47–6.69) for Quartile 3, and 3.63 (95% CI 1.52–8.68) for Quartile 4 for LBW. The adjusted ORs of LBW and SGA among women using supplemental iron were 0.56 (95% CI 0.38, 0.85) and 0.65 (95% CI 0.40, 1.05) compared with non-users, respectively.

Conclusions

Our findings found a linear dose–response relationship between ferritin levels and an increased risk of poor birthweight outcomes, suggesting that maternal ferritin level during pregnancy may provide an additional predictor for differentiating poor birthweight related outcomes. Further exploration should be conducted to ensure maternal ferritin thresholds and iron supplement doses.

Iron Metabolism and Ferroptosis in Physiological and Pathological Pregnancy

Iron is a vital element in nearly every living organism. During pregnancy, optimal iron concentration is essential for both maternal health and fetal development. As the barrier between the mother and fetus, placenta plays a pivotal role in mediating and regulating iron transport. Imbalances in iron metabolism correlate with severe adverse pregnancy outcomes. Like most other nutrients, iron exhibits a U-shaped risk curve. Apart from iron deficiency, iron overload is also dangerous since labile iron can generate reactive oxygen species, which leads to oxidative stress and activates ferroptosis. In this review, we summarized the molecular mechanism and regulation signals of placental iron trafficking under physiological conditions. In addition, we revealed the role of iron metabolism and ferroptosis in the view of preeclampsia and gestational diabetes mellitus, which may bring new insight to the pathogenesis and treatment of pregnancy-related diseases.

Effects of multi-metal exposure on the risk of diabetes mellitus among people aged 40-75 years in rural areas in southwest China

AIMS/INTRODUCTION

Metals play an important role in diabetes mellitus. This cross-sectional study aimed to evaluate the overall, individual and interactive effects of multi-metal exposure on the prevalence of diabetes mellitus, impaired fasting glucose (IFG) rate and fasting blood glucose (FBG) levels.

MATERIALS AND METHODS

The FBG levels of a study population from a cadmium (Cd)-polluted area (n = 250) and an unpolluted area (n = 204), and the metal levels, including magnesium, calcium (Ca), iron (Fe), zinc (Zn), arsenic (As), Cd, copper and lead (Pb) in blood and urine were detected. The study population was divided into a normal fasting glucose group, an IFG group and a diabetes mellitus group on the basis of FBG levels.

RESULTS

The IFG rate and diabetes mellitus prevalence were negatively associated with blood Cd and urine Zn levels (IFG rate: odds ratio [OR] 0.780, 95% confidence interval [CI] 0.655-0.928; OR 0.622, 95% CI 0.465-0.831. Diabetes mellitus prevalence: OR 0.506, 95% CI 0.288-0.888; OR 0.609, 95% CI 0.395-0.939), the IFG rate was positively associated with urine Fe levels (OR 1.876, 95% CI 1.290-2.778), and diabetes mellitus prevalence was positively associated with urine Pb and blood Fe levels (OR 1.185, 95% CI 1.022-1.376; OR 1.008, 95% CI 1.001-1.014). A linear negative correlation was observed between FBG levels and blood Cd, and non-linear inverted U-shaped associations were found between FBG levels and Zn, Pb and copper in urine.

CONCLUSIONS

This research suggests that multi-metal exposure, especially Cd, Fe, Zn, copper and Pb, is linked to diabetes mellitus, and the interactive effects of multiple metals require further exploration.

Timing of gestational weight gain in association with birth weight outcomes: a prospective cohort study

Maternal gestational weight gain (GWG) is an important determinant of infant birth weight, and having adequate total GWG has been widely recommended. However, the association of timing of GWG with birth weight remains controversial. We aimed to evaluate this association, especially among women with adequate total GWG. In a prospective cohort study, pregnant women's weight was routinely measured during pregnancy, and their GWG was calculated for the ten intervals: the first 13, 14-18, 19-23, 24-28, 29-30, 31-32, 33-34, 35-36, 37-38 and 39-40 weeks. Birth weight was measured, and small-for-gestational-age (SGA) and large-for-gestational-age were assessed. Generalized linear and Poisson models were used to evaluate the associations of GWG with birth weight and its outcomes after multivariate adjustment, respectively. Of the 5049 women, increased GWG in the first 30 weeks was associated with increased birth weight for male infants, and increased GWG in the first 28 weeks was associated with increased birth weight for females. Among 1713 women with adequate total GWG, increased GWG percent between 14 and 23 weeks was associated with increased birth weight. Moreover, inadequate GWG between 14 and 23 weeks, compared with the adequate GWG, was associated with an increased risk of SGA (43 (13·7 %) v. 42 (7·2 %); relative risk 1·83, 95 % CI 1·21, 2·76). Timing of GWG may influence infant birth weight differentially, and women with inadequate GWG between 14 and 23 weeks may be at higher risk of delivering SGA infants, despite having adequate total GWG.

Associations between maternal iron supplementation in pregnancy and offspring growth and cardiometabolic risk outcomes in infancy and childhood

It was previously observed that maternal iron supplementation in pregnancy was associated with increased offspring size and adiposity at birth, possibly mediated through increased risk of gestational diabetes. In this study we investigated potential long-term associations of maternal iron supplementation in pregnancy with offspring growth in infancy, and growth and cardiometabolic risk factors in mid-childhood to seek evidence of nutritional programming. Using a nested case-control format, markers of growth and adiposity were measured at 3, 12 and 24 months of age in 341 infants from the Cambridge Baby Growth Study whose mothers supplemented with iron in pregnancy and 222 infants whose mothers did not. Measures of growth, glucose tolerance (using a 30 minute 1.75 g glucose/kg body weight oral glucose tolerance test), insulin sensitivity (HOMA IR) and blood pressure were collected in 122 and 79 of these children, respectively, at around 9.5 years of age. In infancy adiposity-promoting associations with maternal iron supplementation in pregnancy were evident at 3 months of age (e.g. mean difference in skinfold thickness: β = +0.15 mm, p = 0.02, in n = 341 whose mothers supplemented versus 222 that did not; waist circumference: β = +0.7 cm, p = 0.04, in n = 159 and 78, respectively) but differences lessened after this time (e.g. 3–12 month change in mean difference in skinfold thickness: β = -0.2 mm, p = 0.03, in n = 272 and 178, respectively). At ~9.5 years of age children whose mothers supplemented with iron in pregnancy had lower mean arterial blood pressures (β = -1.0 mmHg, p = 0.03, in n = 119 and 78, respectively). There were no apparent differences in markers of growth or other cardiometabolic factors. These results suggest that most of the associations of maternal iron supplementation in pregnancy on growth and adiposity evident at birth disappear during infancy, but there may be some evidence of long-term nutritional programming of blood pressure in mid-childhood.

Multiple micronutrient supplements versus iron-folic acid supplements and maternal anemia outcomes: an iron dose analysis

Antenatal multiple micronutrient supplements (MMS) are more effective than iron and folic acid (IFA) supplements in reducing adverse pregnancy outcomes. Questions remain, however, about the ability of MMS to prevent anemia as effectively as IFA, especially at a lower dose of daily iron and in areas of high anemia prevalence. Analyzing data from 11 trials from a recent Cochrane review, we compared MMS to IFA, delivering either 30 or 60 mg of iron, in sustaining hemoglobin and preventing third trimester anemia and iron deficiency anemia (IDA), accounting for daily iron dose, total supplemental iron intake, and baseline prevalence of anemia. There were no differences between MMS and IFA in third trimester hemoglobin concentration or risks of anemia or IDA by iron dose or total supplemental iron consumed. MMS providing 30 mg of iron was comparable to IFA with 60 mg of iron: mean hemoglobin difference of −0.26 g/L (95% CI: −1.41 to 0.89), risk ratios of 0.99 (95% CI: 0.92–1.07) for anemia, and 1.31 (95% CI: 0.66–2.60) for IDA. Baseline prevalence of anemia did not explain heterogeneity in findings. Compared to IFA, MMS results in comparable hemoglobin concentration and protection against anemia during pregnancy, independently of iron dose.

Association Between Serum Ferritin Concentration and Risk of Adverse Maternal and Fetal Pregnancy Outcomes: A Retrospective Cohort Study

OBJECTIVE

This study evaluated the associations of serum ferritin (SF) concentration during pregnancy with the risk of adverse maternal and fetal pregnancy outcomes.

METHODS

We conducted a retrospective study of 2327 pregnant women from 2015 to 2020 in Guangdong, China. SF concentrations were measured at 16-18th and 28-32th week of gestation. Logistic regression models were applied to estimate the association between SF concentration and the risk of adverse pregnancy outcomes.

RESULTS

After multivariable adjustment, the odds ratio (OR) of the highest quartile of SF concentration at 16-18th week of gestation was 1.43 (95% confidence interval [CI]: 1.09, 1.89) for gestational diabetes mellitus (GDM) and 1.79 (95% CI: 1.15, 2.79) for small for gestational age (SGA) when compared with the lowest quartile. At 28-32th week of gestation compared with the lowest quartile, women with SF in the highest quartile had an increased risk of SGA (OR: 1.62; 95% CI: 1.01, 2.62). Moreover, the lowest quartile of SF concentration decreased risk of SGA by 90% (95% CI: 0.01, 0.80) when compared with the highest quartile among pregnancy women with GDM.

CONCLUSION

Elevated SF concentrations increased the risk of GDM and SGA during pregnancy. Maintaining an appropriately low level of maternal SF at 28-32th week of gestation in women with GDM could reduce the risk of SGA.