A Prospective Study of Early-pregnancy Thyroid Markers, Lipid Species, and Risk of Gestational Diabetes Mellitus

Lipid Metabolism in Pregnancy Women with Hypothyroidism and Potential Influence on Pregnancy Outcome

Thyroid hormone (TH) is essential for maintaining normal physiological processes during pregnancy, including the metabolism of energy materials in both the mother and fetus and the growth and development of fetal bone and nervous system. TH can act on the liver, fat, and other tissues and organs to participate in lipid synthesis and breakdown through multiple pathways. Consequently, abnormal thyroid function is often accompanied by lipid metabolism disorders. Both clinical and subclinical hypothyroidism, as well as dyslipidemia during pregnancy, have been shown to be associated with an increased risk of multiple adverse pregnancy outcomes. Recently, there has been an increased interest in studying the alteration of lipidomic and hypothyroidism (both clinical and subclinical hypothyroidism) during pregnancy. Studies have suggested that altered lipid molecules might be used as potential biomarker and associated with adverse maternal and neonatal outcome. Thus, we summarized the associations between lipid metabolism and clinical or subclinical hypothyroidism during pregnancy in this review. Then, we discussed the underlying mechanisms of thyroid dysfunction and lipid metabolism. In addition, we reviewed the possible effect of dyslipidemia on pregnancy and neonatal outcome. However, the relationship between hypothyroidism during pregnancy and changes in the lipid profile and how to intervene in the occurrence and development of adverse pregnancy outcomes require further study.

Associations between OGTT results during pregnancy and offspring TSH levels: a birth cohort study

BACKGROUND

Limited evidence exists regarding the association between gestational diabetes mellitus (GDM) and elevated levels of thyroid-stimulating hormone (TSH) in newborns. Therefore, this study aimed to investigate the potential risk of elevated TSH levels in infants exposed to maternal GDM, considering the type and number of abnormal values obtained from the 75-gram oral glucose tolerance test (OGTT).

METHODS

A population-based, prospective birth cohort study was conducted in Wuhan, China. The study included women who underwent GDM screening using a 75-g OGTT. Neonatal TSH levels were measured via a time-resolved immunofluorescence assay. We estimated and stratified the overall risk (adjusted Risk Ratio [RR]) of elevated TSH levels (defined as TSH > 10 mIU/L or > 20 mIU/L) in offspring based on the type and number of abnormal OGTT values.

RESULTS

Out of 15,236 eligible mother-offspring pairs, 11.5% (1,753) of mothers were diagnosed with GDM. Offspring born to women diagnosed with GDM demonstrated a statistically significant elevation in TSH levels when compared to offspring of non-GDM mothers, with a mean difference of 0.20 [95% CI: 0.04-0.36]. The incidence of elevated TSH levels (TSH > 10 mIU/L) in offspring of non-GDM women was 6.3 per 1,000 live births. Newborns exposed to mothers with three abnormal OGTT values displayed an almost five-fold increased risk of elevated TSH levels (adjusted RR 4.77 [95% CI 1.64-13.96]). Maternal fasting blood glucose was independently and positively correlated with neonatal TSH levels and elevated TSH status (TSH > 20 mIU/L).

CONCLUSIONS

For newborns of women with GDM, personalized risk assessment for elevated TSH levels can be predicated on the type and number of abnormal OGTT values. Furthermore, fasting blood glucose emerges as a critical predictive marker for elevated neonatal TSH status.

Establishment of gestational diabetes risk prediction model and clinical verification

OBJECTIVE

The present study aimed to evaluate the risk factors for gestational diabetes mellitus (GDM) and build and validate an early risk prediction model of GDM by comparing the differences in the indicators of the first trimester of pregnancy between pregnant women with GDM and non-gestational diabetes mellitus (NGDM). Thus, this study provided a theoretical basis for early intervention of GDM.

METHODS

A total of 6000 pregnant women who underwent a routine prenatal examination in Qinhuangdao Maternal and Child Health Hospital (Qinhuangdao City, Hebei Province, China) from January 2016-2022 were retrospectively selected and randomly divided into a modeling cohort (4200 cases) and validation cohort (1800 cases) at a ratio of 3:7. According to the results of oral glucose tolerance test (OGTT), they were divided into NGDM and GDM groups. The modeling cohort consisted of 2975 NGDM and 1225 GDM cases, while the validation cohort consisted of 1281 NGDM and 519 GDM cases. The differences in general conditions and laboratory indicators between different groups were compared, and logistic regression analysis was further used to establish a risk prediction model for GDM in the first trimester. The receiver operating characteristic curve (ROC) and Hosmer-Lemeshow (HL) tests were used to evaluate the prediction of the model efficacy.

RESULTS

Age, pre-pregnancy body mass index (BMI), glycosylated hemoglobin (HbA1c), blood uric acid (UA), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C) in the first trimester were independent risk factors for GDM (P < 0.05). The model equation was Y = 1/{1 + exp[- (- 18.373 + age × 0.065 + BMI × 0.030 + first-trimester HbA1c × 2.519 + UA × 0.014 + TG × 0.224-HDL-C × 0.635)]}. The area under the ROC curve (AUC) of the model cohort was 0.803 (0.788-0.817), the sensitivity was 72.0%, and the specificity was 73.5%. The AUC of the validation cohort was 0.782 (0.759-0.806), the sensitivity was 68.6%, and the specificity was 73.8%. The P values of the HL test in both the training and validation sets were > 0.05, indicating a satisfactory model fit.

CONCLUSION

Age, pre-pregnancy BMI, HbA1C in early pregnancy, blood UA, TG, and HDL-C are independent risk factors for GDM. The risk prediction model established by combining age, pre-pregnancy BMI, and laboratory indicators in the first trimester can provide a theoretical basis for early screening, monitoring, and intervention of GDM high-risk pregnant women.

The association between dyslipidaemia in the first trimester and adverse pregnancy outcomes in pregnant women with subclinical hypothyroidism: a cohort study

BACKGROUND

Subclinical hypothyroidism (SCH) is linked to dyslipidaemia and adverse pregnancy outcomes. However, the impact of dyslipidaemia on the outcome of pregnancy in SCH is unclear.

METHODS

We enrolled 36,256 pregnant women and evaluated their pregnancy outcomes. The following data was gathered during the first trimester (≤ 13+ 6 weeks of gestation): total cholesterol (TC), low-density lipoprotein (LDL-C), triglyceride (TG), high-density lipoprotein (HDL-C), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) concentrations. The reference ranges for lipids were estimated to range from the 5th to the 95th percentile. Logistic regression assessed the relationships between dyslipidaemia and adverse pregnancy outcomes, including abortion, preeclampsia/eclampsia, low birth weight, foetal growth restriction, premature rupture of foetal membranes, gestational hypertension, preterm birth, macrosomia and gestational diabetes mellitus (GDM). Additionally, the best thresholds for predicting adverse pregnancy outcomes based on TSH, FT4, and lipid levels were determined using receiver operating characteristic curves.

RESULTS

In the first trimester, LDL-C > 3.24 mmol/L, TG > 1.92 mmol/L, HDL-C < 1.06 mmol/L, and TC > 5.39 mmol/L were used to define dyslipidaemia. In this cohort, 952 (3.56%) patients were diagnosed with SCH, and those who had dyslipidaemia in the first trimester had higher incidences of gestational hypertension (6.59% vs. 3.25%), preeclampsia/eclampsia (7.14% vs. 3.12%), GDM (22.53% vs. 13.77%), and low birth weight (4.95% vs. 2.08%) than did those without dyslipidaemia. However, after adjusting for prepregnancy body mass index (pre-BMI), dyslipidaemia was no longer related to these risks. Furthermore, elevated TG dyslipidaemia in SCH patients was connected to an enhanced potential of gestational hypertension (odds ratio [OR]: 2.687, 95% confidence interval [CI]: 1.074 ~ 6.722), and elevated LDL-C dyslipidaemia correlated with increased preeclampsia/eclampsia risk (OR: 3.172, 95% CI: 1.204 ~ 8.355) after accounting for age, smoking status, alcohol use, pre-BMI, and levothyroxine use. Additionally, the combination of TC, TG, LDL-C, pre-BMI, and TSH exhibited enhanced predictive capabilities for gestational hypertension, preeclampsia/eclampsia, and GDM. Values of 0.767, 0.704, and 0.706 were obtained from the area under the curve.

CONCLUSIONS

Among pregnant women with SCH, dyslipidaemia in early pregnancy was related to elevated risks of adverse pregnancy consequences. The combined consideration of age, pre-BMI, TSH, and lipid levels in the first trimester could be beneficial for monitoring patients and implementing interventions to reduce adverse pregnancy outcomes.

Association of Maternal TSH, FT4 With Children's BMI Trajectories, and Obesity: A Birth Cohort Study

OBJECTIVE

To investigate the association between maternal TSH, free thyroxine (FT4), and children's body mass index (BMI) trajectories and obesity.

METHOD

Based on the Ma'anshan Birth Cohort in China, we repeatedly assayed maternal thyroid functions in 3 trimesters of pregnancy. Children's height and weight were measured 15 times before they were age 6 years. Body fat was assessed when children were aged 6 years. Mplus software was used to fit maternal thyroid hormone trajectories and BMI trajectories. Multivariate logistic regression models and generalized linear models were used in data analysis.

RESULTS

Low maternal FT4 trajectory was observed to be related to an increased risk of a high children's BMI trajectory and overweight, with an odds ratio and 95% CI of 1.580 (1.169-2.135) and 1.505 (1.064-2.129), respectively. Increased maternal FT4 concentrations in the first, second, and third trimesters were associated with a decreased risk of high children's BMI trajectories and obesity. There was a positive association between low maternal FT4 trajectory and 6-year-old children's body fat ratio with β and 95% CI of 0.983 (0.138-1.829). Furthermore, negative correlations between maternal FT4 concentration in the first, second, and third trimesters of pregnancy and body fat ratio were observed.

CONCLUSIONS

Low maternal FT4 trajectory during pregnancy may predict a high BMI trajectory in children and relate to overweight and high body fat ratio in 6-year-old children. High maternal FT4 concentrations throughout pregnancy may be associated with the decreasing risk of obesity and low body fat ratio in 6-year-old children.

Combined healthy lifestyle in early pregnancy and risk of gestational diabetes mellitus: A prospective cohort study

OBJECTIVE

To examine the association of a combined healthy lifestyle in early pregnancy with gestational diabetes mellitus (GDM) risk.

DESIGN, SETTING AND POPULATION

A Chinese prospective cohort study with 6980 pregnant women.

METHODS

Individual modifiable lifestyle factors were assessed in early pregnancy and a combined lifestyle score was derived from the sum of the lifestyle factors, with a higher score indicating a healthier lifestyle. The association of a combined healthy lifestyle with GDM risk was examined.

MAIN OUTCOME MEASURES

Gestational diabetes mellitus was diagnosed in middle pregnancy according to the International Association of Diabetes and Pregnancy Study Group criteria or diagnoses in medical records.

RESULTS

Overall, 501 (7.2%) pregnant women were diagnosed with GDM. Being physically active (total energy expenditure in upper three quintiles, i.e. ≥100.1 metabolic equivalent of task [MET]-hours/week; odds ratio [OR] 0.76, 95% confidence interval [CI] 0.63-0.92), healthy diet (total intake of vegetables and fruits ≥5 times/day; OR 0.74, 95% CI 0.59-0.94), sufficient sleep (night-time sleep duration ≥7 hours/night; OR 0.66, 95% CI 0.48-0.90) and healthy weight (early-pregnancy BMI <24.0 kg/m2 ; OR 0.57, 95% CI 0.46-0.71) were associated with lower GDM risk. The GDM risk decreased linearly across the combined lifestyle score (Ptrend  <0.001): women with 2, 3 and 4 lifestyle factors compared with those with 0-1 factor had 38% (OR 0.62, 95% CI 0.46-0.84), 57% (OR 0.43, 95% CI 0.31-0.58) and 66% (OR 0.34, 95% CI 0.22-0.52) lower risks of GDM, respectively.

CONCLUSION

A healthy lifestyle in early pregnancy was associated with a substantially lower GDM risk.

Free triiodothyronine (FT3)-to-free thyroxine (FT4) ratio identified as a risk factor for gestational diabetes in euthyroid pregnant women: insights from a Chinese population cohort study

Background

To explore the association between thyroid hormones and gestational diabetes mellitus in euthyroid pregnant women, with the aim of preventing the occurrence of gestational diabetes mellitus.

Methods

In this prospective study, a total of 1222 euthyroid pregnant women in their first trimester were recruited at Peking University International Hospital between December 2017 and March 2019. These participants underwent an oral glucose tolerance test during the 24-28 weeks of gestation.

Results

During early pregnancy, the gestational diabetes mellitus group displayed lower levels of free thyroxine when compared to the non-gestational diabetes mellitus group. Additionally, the ratio of free triiodothyronine to free thyroxine in the gestational diabetes mellitus group during early pregnancy was significantly higher (p<0.05). The ratio of free triiodothyronine to free thyroxine during early pregnancy showed a positive correlation with blood glucose levels at 0, 60, and 120 min both before and after glucose loading (all p<0.05). During early pregnancy, there was a negative relationship between free thyroxine levels and fasting blood glucose. The free triiodothyronine levels were positively correlated to blood glucose levels at 120 min following glucose loading (all p<0.05).

Conclusion

The ratio of free triiodothyronine-to-free thyroxine is an independent risk factor for gestational diabetes mellitus and has the potential to be a predictor for gestational diabetes mellitus in euthyroid pregnant women.

Blood Cell Parameters From Early to Middle Pregnancy and Risk of Gestational Diabetes Mellitus

CONTEXT

Chronic low-grade inflammation may play a crucial role in the pathogenesis of gestational diabetes mellitus (GDM). However, prospective studies on the relations of inflammatory blood cell parameters during pregnancy with GDM are lacking.

OBJECTIVE

To prospectively investigate the associations of inflammatory blood cell parameters in both early and middle pregnancy, and their change patterns from early to middle pregnancy, with GDM risk.

METHODS

We used data from the Tongji-Shuangliu Birth Cohort. Inflammatory blood cell parameters (white blood cells [WBC], neutrophils, lymphocytes, monocytes, neutrophil to lymphocyte ratio [NLR], and platelets) were assayed before 15 weeks and between 16 and 28 weeks of gestational age. Logistic regression was used to evaluate the associations between inflammatory blood cell parameters and GDM.

RESULTS

Of the 6354 pregnant women, 445 were diagnosed with GDM. After adjustment for potential confounders, WBC, neutrophils, lymphocytes, monocytes, and NLR in early pregnancy were positively associated with GDM risk (odds ratios [95% CI] for extreme-quartile comparison were 2.38 [1.76-3.20], 2.47 [1.82-3.36], 1.40 [1.06-1.85], 1.69 [1.27-2.24], and 1.51 [1.12-2.02], respectively, all P for trend ≤ .010). Similarly, higher levels of WBC, neutrophils, monocytes, and NLR in middle pregnancy were associated with increased risk of GDM (all P for trend ≤ .014). Stable high levels (≥ median in both early and middle pregnancy) of WBC, neutrophils, monocytes, and NLR were positively associated with GDM risk (all P ≤ .001).

CONCLUSION

Increased WBC, neutrophils, monocytes, and NLR in both early and middle pregnancy and their stable high levels from early to middle pregnancy were associated with higher GDM risk, highlighting that they might be clinically relevant for identifying individuals at high risk for GDM.

Correlation between serum beta-human chorionic gonadotropin levels and thyroid metabolic function in pregnant women with hyperemesis gravidarum

As previously demonstrated, serum beta-human chorionic gonadotropin (β-hCG) is linked to identifying early gestational abnormalities. This research was aimed at investigating the correlation between serum β-hCG levels and thyroid metabolic function in pregnant women with hyperemesis gravidarum (HG). Ninety-one pregnant women with HG were selected as the study group and divided into early pregnancy (EP), mid-pregnancy (MP), and late pregnancy (LP) groups according to their gestational weeks, while 84 normal pregnant women were selected as the control group. Venous blood was collected from pregnant women in both groups and serum β-hCG levels were measured by chemiluminescent immunoassay. The levels of free thyroxine (FT4), free triiodothyronine (FT3), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), thyroid-stimulating hormone receptor antibody (TRAb), and thyroglobulin antibody (TgAb) were tested by chemiluminescent microparticle immunoassay. Visual analog scale (VAS) scores were utilized to assess the degree of HG. Pearson analysis was implemented to measure the correlations between serum β-hCG levels and serum FT3, FT4, TSH, TPOAb, TRAb, TgAb, as well as VAS scores and the correlations between β-hCG, FT3, FT4, TSH, TPOAb, TRAb, TgAb, as well as VAS scores and gestation period. The receiver operating characteristic (ROC) curve was plotted to analyze the diagnostic values of thyroid hormones, thyroid-related antibodies, and β-hCG levels for HG. Versus those in the control group, β-hCG, FT3, FT4, TPOAb, TRAb, TgAb levels, and VAS scores were higher and TSH levels were lower in the study group. Versus those in the EP group, β-hCG, FT3, FT4, TPOAb, TRAb, TgAb levels, and VAS scores of pregnant women in the MP and LP groups were decreased, and TSH levels were increased. Serum β-hCG levels of pregnant women with HG were positively correlated with FT3, FT4, TPOAb, TRAb, TgAb, and VAS scores and negatively correlated with TSH levels. Serum β-hCG, FT3, FT4, TPOAb, TRAb, TgAb levels, and VAS scores of pregnant women with HG had a negative correlation with the gestation period, while TSH levels had a positive correlation with the gestation period. The ROC curve analysis showed that β-hCG and thyroid function-related indicators were of high clinical values in the diagnosis of HG. Collectively, our article suggests that serum β-hCG expression of pregnant women with HG is abnormally elevated and closely related to the degree of HG and hyperthyroidism. In addition, β-hCG and thyroid function-related indicators have certain diagnostic efficacy for HG.

Exposure to per- and polyfluoroalkyl substances in early pregnancy, risk of gestational diabetes mellitus, potential pathways, and influencing factors in pregnant women: A nested case-control study

Although previous studies have reported an association between maternal serum perfluoroalkyl substance (PFAS) exposure and gestational diabetes mellitus (GDM) risk, results have been inconsistent. Few studies have focused on the combined effects of emerging and legacy PFASs on glucose homeostasis while humans are always exposed to multiple PFASs simultaneously. Moreover, the potential pathways by which PFAS exposure induces GDM are unclear. A total of 295 GDM cases and 295 controls were enrolled from a prospective cohort of 2700 pregnant women in Shanghai, China. In total, 16 PFASs were determined in maternal spot serum samples in early pregnancy. We used conditional logistic regression, multiple linear regression, and Bayesian kernel machine regression (BKMR) to examine individual and joint effects of PFAS exposure on GDM risk and oral glucose tolerance test outcomes. The mediating effects of maternal serum biochemical parameters, including thyroid and liver function were further assessed. Maternal perfluorooctanoic acid (PFOA) exposure was associated with an increased risk of GDM (odds ratio (OR) = 1.68; 95% confidence interval (95% CI): 1.10, 2.57), consistent with higher concentrations in GDM cases than controls. Based on mediation analysis, an increase in the free triiodothyronine to free thyroxine ratio partially explained the effect of this association. For continuous glycemic outcomes, positive associations were observed between several PFASs and 1-h and 2-h glucose levels. In BKMR, PFAS mixture exposure showed a positive trend with GDM incidence, although the CIs were wide. These associations were more pronounced among women with normal pre-pregnancy body mass index (BMI). Mixed PFAS congeners may affect glucose homeostasis by increasing 1-h glucose levels, with perfluorononanoic acid found to be a main contributor. Exposure to PFASs was associated with increased risk of GDM and disturbance in glucose homeostasis, especially in normal weight women. The PFAS-associated disruption of maternal thyroid function may alter glucose homeostasis.

Association between prepregnancy weight change and risk of gestational diabetes mellitus in Chinese pregnant women

BACKGROUND

Evidence regarding prepregnancy weight change and gestational diabetes mellitus (GDM) is lacking among East Asian women.

OBJECTIVE

Our study aimed to investigate the association between weight change from age 18 years to pregnancy and GDM in Chinese pregnant women.

METHODS

Our analyses included 6972 pregnant women from the Tongji-Shuangliu Birth Cohort. Body weights were recalled for age 18 years and the time point immediately before pregnancy, while height was measured during early pregnancy. Prepregnancy weight change was calculated as the difference between weight immediately before pregnancy and weight at age 18 years. GDM outcomes were ascertained by 75-g oral glucose tolerance test. Multivariable logistic regression models were used to estimate the association between prepregnancy weight change and risk of GDM.

RESULTS

501 (7.2%) developed GDM in the cohort. After multivariable adjustments, prepregnancy weight change was linearly associated with a higher risk of incident GDM (P < 0.001). Compared with participants with stable weight (weight change within 5.0 kg) before pregnancy, multivariable-adjusted odds ratios and 95% confidence intervals were 1.55 (1.22, 1.98) and 2.24 (1.78, 2.83) for participants with moderate (weight gain of 5-9.9 kg) and high (weight gain ≥ 10 kg) weight gain, respectively. In addition, overweight/obesity immediately before pregnancy mediated 17.6% and 31.7% of the associations of moderate and high weight gain with GDM risk, while weekly weight gain during pregnancy mediated 21.1% and 22.7% of the associations.

CONCLUSIONS

Weight gain from age 18 years to pregnancy was significantly associated with a higher risk of GDM. Maintaining weight stability, especially prevention of excessive weight gain from early adulthood to pregnancy could be a potential strategy to reduce GDM risk.

Association of Early Pregnancy Free and Total Triiodothyronine With the Subsequent Risk of Gestational Diabetes Mellitus

OBJECTIVE

To estimate the association of free triiodothyronine (FT3) and total triiodothyronine (TT3) in early pregnancy and subsequent gestational diabetes mellitus (GDM) risk and define appropriate TT3 thresholds for GDM screening.

METHODS

This investigation is a hospital-based cohort study of pregnant women submitted to a universal thyroid function test before 24 weeks of gestation. GDM was diagnosed according to a 75-g oral glucose tolerance test. The association of maternal high FT3 and TT3 levels in early pregnancy with the risk of GDM was estimated using logistic regression. The potential nonlinear association was probed by the restricted cubic spline curve method.

RESULTS

A total of 27 184 pregnant women and 3073 GDM cases were included in the analysis. FT3 and TT3 were associated with an increased subsequent risk of GDM in a nonlinear fashion. The adjusted odds ratios were 1.59 (95% confidence interval, 1.50-1.68) and 2.80 (95% confidence interval, 2.46-3.18) for FT3 and TT3 continuous levels, respectively. Associations were strong in euthyroid women, showed heterogeneity in women with mild thyroid dysfunction, and lacked in patients with overt hypothyroidism and hyperthyroidism. The TT3 thresholds of 1.5 and 2.0 ng/mL between 7 and 12 weeks of gestation and 1.6 and 2.1 ng/mL for 13 to 23 weeks of gestation effectively distinguished the subsequent risk of GDM.

CONCLUSION

The increased FT3 and TT3 levels in early pregnancy were associated with a subsequent higher risk of GDM. These findings provide measures for early detection and potential prevention of GDM.

Higher Thyroid fT3-to-fT4 Ratio Is Associated with Gestational Diabetes Mellitus and Adverse Pregnancy Outcomes

Aim: To determine the association between thyroid function and the risk of developing gestational diabetes mellitus (GDM) and adverse pregnancy outcomes. Methods: This case−control study was a sub-analysis of the BEDIP-N study, in which 199 GDM women were matched for age and body mass index with 398 controls. Thyroid-stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and thyroid peroxidase (TPO) antibodies were measured at 6−14 weeks and 26−28 weeks during pregnancy. TSH and fT4 were also measured in early postpartum in GDM women. Results: The fT3-to-fT4 ratio at 26−28 weeks was positively associated with GDM risk with an adjusted odds ratio (aOR for smoking, education, parity, ethnicity, gestational weight gain, and (family) history of diabetes or GDM) of 2.12 (95% CI 1.07; 4.23), comparing the highest with the lowest tertile. Higher fT3 levels and a higher fT3-to-fT4 ratio were associated with a less favorable metabolic profile with higher BMI and more insulin resistance during pregnancy and postpartum. Women in the upper fT3 tertile and the upper fT3-to-fT4 ratio had a higher rate of preeclampsia [4.6% (10) vs. 1.0% (2), p = 0.040, and 4.4% (9) vs. 0.5% (1), p = 0.020], gestational hypertension [8.3% (18) vs. 3.1% (6), p = 0.034 and 8.9% (18) vs. 2.0% (4), p = 0.003], and caesarean sections [29.4% (63) vs. 16.1% (31), p = 0.002 and 32.2% (65) vs. 12.7% (25), p < 0.001]. Conclusion: A higher fT3-to-fT4 ratio late into pregnancy was associated with GDM, adverse pregnancy outcomes, and an adverse metabolic profile in early postpartum.

The interactive effects of pre-pregnancy body mass index, thyroid function, and blood lipid levels on the risk of gestational diabetes mellitus: a crossover analysis

Background

Studies have demonstrated the associations between pre-pregnancy obesity, thyroid dysfunction, dyslipidemia, and increased risk of gestational diabetes mellitus (GDM) in pregnant women. This study was designed to investigate whether and to what extent, the interactions between these factors contribute to the risk of GDM.

Methods

A case–control study of 232 GDM cases and 696 controls was conducted among pregnant women from Hangzhou, China. Multiple logistic regression analysis was applied to identify independent risk factors of GDM. Crossover analysis was performed to assess the interactive effects of pre-pregnancy body mass index (pBMI), thyroid hormones, and blood lipid profiles on the risk of GDM. The indexes including attributable proportion (AP) to the interaction and the relative excess risk due to interaction (RERI) were calculated.

Results

Chinese pregnant women with pBMI > 23 kg/m² (adjusted: OR = 4.162, p < 0.001), high triglyceride levels (> 2.30 mmol/L) (adjusted: OR = 1.735, p < 0.001), and the free triiodothyronine/free thyroxine (FT3/FT4) ratio ≥ 0.502 (OR = 4.162, p < 0.001) have significantly increased risk of GDM. Crossover analysis indicated that there were significant interactions between pre-pregnancy overweight/obesity and FT3/FT4 ≥ 0.502 (AP = 0.550, p < 0.001; RERI = 7.586, p = 0.009), high TG levels and FT3/FT4 ≥ 0.502 (AP = 0.348, 95%CI = 0.081–0.614, P = 0.010; RERI = 2.021, 95%CI = 0.064–3.978, p = 0.043) on the risk of GDM.

Conclusion

The interactions between pBMI and FT3/FT4 ratio, TG level and FT3/FT4 ratio may have significant impacts on the risk of GDM in pregnant women. Such findings may help improve our understanding of the pathogenesis of GDM as well as develop comprehensive strategies for the management of GDM.

A Prospective Study of Early-pregnancy Thyroid Markers, Lipid Species, and Risk of Gestational Diabetes Mellitus

CONTEXT

While the associations between thyroid markers and gestational diabetes mellitus (GDM) have been extensively studied, the results are inconclusive and the mechanisms remain unclear.

OBJECTIVE

We aimed to investigate the prospective associations of thyroid markers in early gestation with GDM risk, and examine the mediating effects through lipid species.

METHODS

This study included 6068 pregnant women from the Tongji-Shuangliu Birth Cohort. Maternal serum thyroid markers (free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone, thyroid peroxidase antibody, and thyroglobulin antibody) were measured before 15 weeks. Deiodinase activity was assessed by fT3/fT4 ratio. Plasma lipidome were quantified in a subset of 883 participants.

RESULTS

Mean age of the participants was 26.6 ± 3.7 years, and mean gestational age was 10.3 ± 2.0 weeks. Higher levels of fT4 were associated with a decreased risk of GDM (OR = 0.73 comparing the extreme quartiles; 95% CI 0.54, 0.98, Ptrend = .043), while higher fT3/fT4 ratio was associated with an increased risk of GDM (OR = 1.43 comparing the extreme quartiles; 95% CI 1.06, 1.93, Ptrend = .010) after adjusting for potential confounders. Multiple linear regression suggested that fT3/fT4 ratio was positively associated with alkylphosphatidylcholine 36:1, phosphatidylethanolamine plasmalogen 38:6, diacylglyceride 18:0/18:1, sphingomyelin 34:1, and phosphatidylcholine 40:7 (false discovery rate [FDR] adjusted P < .05). Mediation analysis indicated 67.9% of the association between fT3/fT4 ratio and GDM might be mediated through the composite effect of these lipids.

CONCLUSION

Lower concentration of serum fT4 or higher fT3/fT4 ratio in early pregnancy was associated with an increased risk of GDM. The association of fT3/fT4 ratio with GDM was largely mediated by specific lipid species.

FT3/FT4 mediated the effect of pre-pregnancy body mass index or maternal weight gain during early pregnancy on gestational diabetes mellitus

OBJECTIVE

Maternal overweight or obesity during early pregnancy could increase the subsequent risk of gestational diabetes mellitus (GDM). However, whether these associations were mediated by thyroid hormones and their effect sizes were still unknown. This study aimed to identify the mediating effects of thyroid parameters between pre-pregnancy body mass index (BMI)/maternal weight gain during early pregnancy with subsequent risk of GDM.

METHODS

This prospective mother-infant cohort study was conducted from 2018 to 2019. A total of 2,772 singleton pregnant women were included for analysis. Questionnaire survey, anthropometric measures, and thyroid function testing were conducted in early pregnancy. Deiodinase activity was evaluated using free-triiodothyronine-to-free-thyroxine ratio (FT3/FT4). A standard 75 g oral glucose tolerance test was performed during 24-28 weeks of gestation to diagnose GDM. Mediation analysis was performed on PROCESS 3.5 to examine the mediating effects of thyroid parameters between pre-pregnancy BMI/maternal weight gain during early pregnancy and the subsequent GDM risk.

RESULTS

FT3/FT4 ratio was a significant mediator between pre-pregnancy BMI or maternal weight gain and GDM, accounting for 16.5% and 18.6% of total effects, respectively. FT3 also mediated the association of pre-pregnancy BMI with GDM, accounting for 3.3% of total effects. Thyroid-stimulating hormone suppressed the effects of pre-pregnancy BMI and maternal weight gain on GDM risk, and the proportions of total effects were 2.4% and 6.4%, respectively.

CONCLUSIONS

Deiodinase activity, as indicated by FT3/FT4 ratio, was the strongest mediator among thyroid parameters between pre-pregnancy BMI/maternal early weight gain and GDM.

Associations of Thyroid Function Tests with Lipid Levels and Adverse Pregnancy Outcomes During the First Trimester

OBJECTIVE

The present study aims to evaluate the relationship of thyroid function during the first trimester of pregnancy with lipid levels and pregnancy outcomes.

METHODS

Women who delivered babies at the Shanghai General Hospital between March 2019 and December 2019 with a known pregnancy outcome and complete data were included in the present study (n = 1779). A retrospective cohort study of all subjects with available first-trimester thyroid function testing and lipid levels data was conducted, and the relationship of thyroid function with lipid levels and pregnancy outcomes was evaluated. The data were analyzed using the SPSS software for statistical correlation.

RESULTS

The proportion of caesarean sections was higher in women with hypothyroxinemia (HIA) and hypothyroidism than in women with euthyroidism. Hypothyroidism was shown to be related with polyhydramnios, preterm labor and hypertriglyceridemia. HIA was correlated with increased rates of gestational diabetes mellitus (GDM), preeclampsia, gestational hypertension and hypertriglyceridemia. Compared with the euthyroidism group, the hypothyroidism group had a higher apolipoprotein A1 (Apo A1) level and apolipoprotein B level; the subclinical hypothyroidism group had a higher total cholesterol (TC) level and low-density lipoprotein cholesterol level; the HIA group had higher triglyceride, high-density lipoprotein cholesterol levels and lower TC, Apo A1 levels. TC levels were positively correlated with the thyroid-stimulating hormone level and negatively correlated with free thyroxine (FT4) level, and free triiodothyronine and FT4 levels were positively correlated with GDM occurrence.

CONCLUSION

Thyroid function in early pregnancy is associated with dyslipidemia and pregnancy outcomes; conventional screening of thyroid diseases in early pregnancy may help improve lipid levels and decrease adverse pregnancy outcomes.

Impaired Sensitivity to Thyroid Hormones Is Associated With Elevated Blood Glucose in Coronary Heart Disease

CONTEXT

Thyroid hormones influence glucose homeostasis through central and peripheral regulation. To date, the association between thyroid hormone sensitivity and elevated blood glucose (EBG) in patients with coronary heart disease (CHD) remains unknown. The purpose of this study was to investigate the association between thyroid hormone sensitivity and risk of EBG in patients with CHD, and to further explore their association in different sexes and ages.

METHODS

This large multicenter retrospective study included 30,244 patients with CHD (aged 30-80 years) between 1 January 2014 and 30 September 2020. Parameters representing central and peripheral sensitivity to thyroid hormones were calculated. Central sensitivity to thyroid hormones was assessed by calculating the Thyroid Feedback Quantile-based Index (TFQI), Thyroid-stimulating Hormone Index (TSHI), and Thyrotropin Thyroxine Resistance Index (TT4RI), and Parametric Thyroid Feedback Quantile-based Index (PTFQI); peripheral sensitivity to thyroid hormones was evaluated using the ratio of free triiodothyronine (FT3) /free thyroxine (FT4). Taking normal glucose tolerance (NGT) as a reference, logistic regression was used to analyse the relationship between central and peripheral thyroid hormone sensitivity and EBG in patients with CHD.

RESULTS

Among the 30,244 participants, 15,493 (51.23%) had EBG. The risk of EBG was negatively correlated with TSHI (OR: 0.91; 95%CI: 0.91 to 0.92; P < 0.001), TT4RI (OR: 0.99; 95% CI: 0.99 to 0.99; P<0.001), TFQI (OR: 0.82; 95%CI: 0.80 to 0.84; P <0.001) and PTFQI (OR: 0.76; 95%CI: 0.74 to 0.78; P<0.001). Compared to males and patients aged 60 and below, the OR value for EBG was lower in females and in patients aged over 60 years old. Conversely, EBG risk was positively associated with FT3/FT4 (OR: 1.08; 95% CI: 1.07 to 1.09; P <0.001) and in the sex-categorized subgroups, males had higher OR values than females.

CONCLUSIONS

This study showed that thyroid hormone sensitivity is significantly associated with EBG in patients with CHD. This association is higher in females than in males, and the association in those aged over 60 years old is higher than that in patients aged 60 years and below.