Association of higher HbA1c within the normal range with adverse pregnancy outcomes: a cross-sectional study

Causal Associations Between Pre-Pregnancy Diabetes Mellitus and Pre-Eclampsia Risk: Insights from a Mendelian Randomization Study

BACKGROUND AND OBJECTIVES

Pre-eclampsia (PE) is a serious pregnancy complication defined by the onset of hypertension and multi-organ dysfunction occurring after 20 weeks of gestation. Studies have indicated the correlation between diabetes mellitus (DM) and PE, but the causal relationship remains unclear.

MATERIALS AND METHODS

The two-sample Mendelian randomization (MR) approach, including the inverse variance weighted random effects (IVW-RE) model and the traditional sensitivity model, was employed to assess the causal effects of pre-pregnancy type 1 diabetes (T1D) and type 2 diabetes (T2D) on PE using summary-level data obtained from genome-wide association studies. Additionally, diabetes-related factors, such as glycated hemoglobin (HbA1c) levels, fasting insulin levels, and body mass index (BMI), were evaluated for their potential causal effects on the risk of PE. Pleiotropy-robust and multivariable Mendelian randomization (MVMR) methods were further used because of the intricate associations among the traits. Insulin and metformin use was also assessed for their causal role in PE risk.

RESULTS

Our findings show that genetically predicted T1D (OR = 1.06, 95% CI: 1.03-1.09, p < 0.001), T2D (OR = 1.09, 95% CI: 1.04-1.14, p < 0.001), and BMI (OR = 1.64, 95% CI 1.49 to 1.80, p < 0.001) had causal effects on the incidence of PE, while the effects of HbA1c (OR = 0.77, 95% CI 0.59 to 1.02, p = 0.064) and fasting insulin levels (OR = 1.35, 95% CI 0.89 to 2.05, p = 0.153) on the occurrence of PE were not significant. The results were verified by MVMR analysis. Additionally, insulin use increased the risk of pre-eclampsia (OR = 1.11, 95% CI 1.05-1.17, p < 0.001).

CONCLUSIONS

Our findings demonstrate a causal relationship between pre-pregnancy diabetes (DM) and obesity and the risk of PE from a genetic epidemiological perspective. Adverse maternal factors, including DM and obesity prior to pregnancy, should be considered in mechanistic studies of PE. In addition, comprehensive interventions for risk factors such as pre-pregnancy DM and obesity should be emphasized in clinical practice.

The Impact of Gestational Diabetes Mellitus on the Development of Preeclampsia in Twin Pregnancies: A Retrospective Cohort Study Conducted at a Tertiary Hospital

Purpose

This study aimed to examine the effects of gestational diabetes mellitus (GDM) on the risk of pregnancy complications in twin pregnancies and to investigate the relationship between glycemic levels and the risk of preeclampsia (PE) and abnormal fetal growth.

Patients and Methods

A retrospective cohort study of 736 twin pregnancies was conducted at a tertiary hospital. Propensity score matching and multivariable logistic models were utilized to compare maternal and neonatal outcomes between twin pregnancies with GDM and those without GDM. Multivariable logistic regressions were performed to address the intertwin correlation between glycemic levels and the primary outcomes.

Results

There was no significant difference in the risk of PE between non-GDM and GDM pregnancies (OR, 0.70; 95% CI: 0.38-1.27; P = 0.238). No statistically significant differences were observed in the prevalence of small for gestational age and large for gestational age between the study groups. A comparative analysis of twin pregnancies affected by PE and GDM versus those without GDM revealed that the former group exhibited similar maternal and neonatal outcome risks. Women with fasting blood glucose levels from 5.1 mmol/L (92mg/dL) to less than 5.3 mmol/L (95.6mg/dL) had a significantly higher risk of PE compared with women without GDM (OR, 2.90; 95% CI: 1.12-7.51; P = 0.028). In subgroups of glycosylated hemoglobin (HbA1c), HbA1c ≥ 5.5% had the highest risk of PE in the second and third trimesters compared with women without GDM (OR, 4.90; 95% CI: 1.00-24.12; P = 0.05).

Conclusion

The risk of PE was not increased in twin pregnancies complicated with GDM, but significantly increased in women with an HbA1c ≥5.5%. No significant associations were observed between the co-occurrence of GDM and PE and the incidence of pregnancy complications in twin pregnancies. Strict glycemic control may decrease the risk of PE in twin pregnancies with GDM.

Association between maternal gestation weight gain and preterm birth according to pre-pregnancy body mass index and HbA1c

BACKGROUND

To investigate the association between gestational weight gain (GWG) and preterm birth (PTB) according to pre-pregnancy body mass index (pp-BMI) and glycated haemoglobin (HbA1c) within the normal range.

METHODS

We conducted a population-based retrospective cohort study between July 2017 and January 2020 at Women's Hospital, Zhejiang University School of Medicine. Women were classified into three groups (inadequate GWG, appropriate GWG, and excessive GWG). In addition, women were divided into different subgroups according to pp-BMI and HbA1c. We estimated the odds ratios (OR) with 95% confidence intervals (CI) to assess the associations between GWG and the risk of PTB. Meanwhile, we adjusted for possible confounding factors, including maternal age, infant sex, family history of diabetes, education, pregnancy mode, delivery mode, parity, and gravidity.

RESULTS

The study involved 23,699 pregnant women, of which 1124 (4.70%) were PTB. Women who had inadequate GWG were found to have a significantly higher risk of PTB compared to women with appropriate GWG. In contrast, women with excessive GWG had a reduced risk of PTB. Similarly, GWG and PTB had similar risk associations in the HbA1c and pp-BMI subgroups. Among women with pp-BMI <18.5 kg/m2, women with inadequate GWG had a significantly increased risk of PTB compared with women in the control group (HbA1c 4.6-5.0%, appropriate GWG), and the risk increased with increasing HbA1c levels. Similar results were observed in women with normal pp-BMI.

CONCLUSIONS

There was a significant association between GWG and the risk of PTB, but the risk varied by pp-BMI and HbA1c levels. Reasonable weight gain during pregnancy is essential to prevent PTB. Furthermore, while HbA1c is within the normal range, the higher levels should be noticed.

Is early pregnancy hemoglobin A1c useful to predict gestational diabetes mellitus diagnosed during mid pregnancy?

AIMS

To verify whether hemoglobin A1c (HbA1c) levels in early pregnancy can predict the diagnosis of gestational diabetes mellitus (GDM) in mid-pregnancy.

MATERIALS AND METHODS

This was a retrospective cohort study of 2008 pregnant women who delivered singletons at the Yokohama City university Medical Center. Concomitant or history of diabetes mellitus and overt diabetes in pregnancy were excluded. Pregnant women at high risk for GDM underwent a one-step 75-g oral glucose tolerance test (OGTT) during mid-pregnancy. For other pregnant women, GDM was diagnosed by a two-step 75-g oral glucose tolerance test (OGTT) when the 50-g glucose challenge test result in mid-pregnancy was ≥140 mg/dL. The thresholds for 75-g OGTT followed those of the International Association of Diabetes and Pregnancy Study Group (IADPSG) criteria (92-180-153 mg/dL). The relationship between HbA1c level measured at <20 weeks of gestation and GDM diagnosis at mid pregnancy was assessed using a receiver operating characteristic curve (ROC); area under the curve (AUC) and optimal cutoff value of HbA1c, predictive of GDM were calculated.

RESULTS

The median HbA1c level at <20 weeks of gestation was 5.3%, and 8.5% of women were diagnosed with GDM. In the ROC curve of the GDM diagnosis rate by HbA1c level, AUC was 0.706, and the optimal cutoff value was 5.4%, with a sensitivity of 0.6176, specificity of 0.6834, positive predictive value of 15.4%, and negative predictive value of 95.1%.

CONCLUSIONS

Although HbA1c at less than 20 weeks of gestation is acceptable discrimination as a diagnostic tool of GDM in mid-pregnancy, it is not clinically useful to predict GDM in mid-pregnancy.

Evidence that highly canalized fetal traits are sensitive to intergenerational effects of maternal developmental nutrition

OBJECTIVES

Maternal experiences before pregnancy predict birth outcomes, a key indicator of health trajectories, but the timing and pathways for these effects are poorly understood. Here we test the hypothesis that maternal pre-adult growth patterns predict pregnancy glucose and offspring fetal growth in Cebu, Philippines.

METHODS

Using multiple regression and path analysis, gestational age-adjusted birthweight and variables reflecting infancy, childhood, and post-childhood/adolescent weight gain (conditional weights) were used to predict pregnancy HbA1c and offspring birth outcomes among participants in the Cebu Longitudinal Health and Nutrition Survey.

RESULTS

Maternal early/mid-childhood weight gain predicted birth weight, length, and head circumference in female offspring. Late-childhood/adolescent weight gain predicted birth length, birth weight, skinfold thickness, and head circumference in female offspring, and head circumference in male offspring. Pregnancy HbA1c did not mediate relationships between maternal growth and birth size parameters.

DISCUSSION

In Cebu, maternal growth patterns throughout infancy, childhood, and adolescence predict fetal growth via a pathway independent of circulating glucose, with stronger impacts on female than male offspring, consistent with a role of developmental nutrition on offspring fetal growth. Notably, the strength of relationships followed a pattern opposite to what occurs in response to acute pregnancy stress, with strongest effects on head circumference and birth length and weakest on skinfolds. We speculate that developmental sensitivities are reversed for stable, long-term nutritional cues that reflect average local environments. These findings are relevant to public health and life-history theory as further evidence of developmental influences on health and resource allocation across the life course.

Trimester-specific reference intervals for hemoglobin A1c in non-diabetic pregnancy in a Chinese population

BACKGROUND

Physiological glycated hemoglobin (HbA1c) values in each trimester are not well defined. This study aimed to determine trimester-specific reference intervals for HbA1c levels in non-diabetic pregnant women in China.

METHODS

In this cross-sectional study, 5,042 Chinese pregnant women from 6 to 41 weeks of gestation were screened. An inclusion of 4,134 non-diabetic women was made to determine the reference intervals, they were divided into three trimesters: trimester 1 (T1), 6 weeks to 13 weeks + 6 days, trimester 2 (T2), 14 weeks to 27 weeks + 6 days, and trimester 3 (T3), 28 weeks to 41 weeks + 6 days. A total of 4,134 women (T1 n = 760, T2 n = 1,953, and T3 n = 1,421) provided blood samples which were analyzed for HbA1c concentrations. HbA1c was measured using high-performance liquid chromatography. The median and percentile (2.5th to 97.5th) for the HbA1c reference intervals were calculated for each trimester.

RESULTS

In total, 8,732 HbA1c measurements were taken. Reference intervals for HbA1c expressed as median and percentile (2.5th to 97.5th) for each trimester were: T1: 4.7 (4.0-5.5%), T2: 4.5 (3.9-5.3%), and T3: 4.8 (4.1-5.7%) respectively. The HbA1c levels were significantly lower in the second trimester compared to those in the first trimester (p < 0.0001), and higher in the third trimester compared to the second trimester (p < 0.0001).

CONCLUSIONS

The reference intervals for HbA1c levels were 3.9-5.7% with upper limits of 5.5% in the first trimester, 5.3% in the second trimester, and 5.7% in the third trimester. These findings highlight the importance of considering trimester-specific reference intervals for HbA1c in non-diabetic pregnant women to promote maternal and fetal health.

Combining HbA1c and insulin resistance to assess the risk of gestational diabetes mellitus: a prospective cohort study

OBJECTIVE

To investigate the association of glycated hemoglobin (HbA1c) and homeostasis model assessment insulin resistance (HOMA-IR) with gestational diabetes mellitus (GDM) risk.

METHODS

Data for this study were from a prospective cohort in Hangzhou, China. We included pregnant women with HbA1c, fasting insulin, and fasting glucose (FG) measured at 15-20 weeks of gestation and underwent oral glucose tolerance test (OGTT) at 24-28 weeks. Based on HbA1c and HOMA-IR, participants were divided into four groups. We estimated the odds ratios (OR) with 95% confidence intervals (CI) to assess the associations of HbA1c and HOMA-IR with GDM occurrence. Finally, we the potential additive interaction between HbA1c and HOMA-IR by calculating relative excess risk due to interaction (RERI) and the attributable proportion due to interaction (AP).

RESULT

462 pregnant women were included, of whom 136 (29.44%) developed GDM. Based on HbA1c and HOMA-IR, the study population was divided into four groups, with the percentages of each group being 51.30%, 15.58%, 20.56%, and 12.55%, respectively. The incidence of GDM increased with the increase of HOMA-IR and HbA1c, respectively, and the risk of GDM was significantly increased when both HOMA-IR and HbA1c were elevated. However, no such risk was observed in pregnant women < 35 years. Finally, we found significantly higher FG at 24-28 weeks in the high HOMA-IR and HbA1c group among GDM-positive pregnant women.

CONCLUSIONS

The incidence of GDM increased with increasing HbA1c and HOMA-IR, and the risk of GDM was significantly increased when both HbA1c and HOMA-IR were elevated. This finding may help to identify high-risk women for GDM early in pregnancy and provide timely interventions.

The association between maternal HbA1c and adverse outcomes in gestational diabetes

BACKGROUND

The role of HbA1c in women with gestational diabetes mellitus (GDM) is still unclear, particularly in the Asian population.

AIM

To investigate the association between HbA1c levels and adverse outcomes considering maternal age, pre-pregnancy body mass index (BMI), and gestational weight gain (GWG) in women with GDM.

METHOD

A retrospective study included 2048 women with GDM and singleton live births. Using logistic regression, the associations between HbA1c and adverse pregnancy outcomes were assessed.

RESULT

Compared to women with HbA1c ≤ 5.0%, HbA1c was significantly associated with macrosomia (aOR 2.63,95%CI1.61,4.31), pregnancy-induced hypertension (PIH, aOR 2.56,95%CI1.57,4.19), preterm birth (aOR 1.64,95%CI 1.05,2.55), and primary Cesarean section (primary C-section, aOR1.49,95%CI1.09,2.03) in GDM women with HbA1c ≥5.5% while significantly associated with PIH (aOR 1.91,95%CI1.24,2.94) in women with HbA1c 5.1-5.4%. The associations between HbA1c and adverse outcomes varied with maternal age, pre-pregnancy BMI, and GWG. In women aged ≤29 years, there's significant association between HbA1c and primary C-section when HbA1c was 5.1-5.4% and ≥5.5%. In women aged 29-34 years and HbA1c ≥5.5%, HbA1c was significantly associated with macrosomia. In women aged ≥35 years, there's significant association between HbA1c and preterm birth when HbA1c was 5.1-5.4% and macrosomia and PIH when HbA1c ≥5.5%. In pre-pregnant normal-weight women, HbA1c was significantly associated with macrosomia, preterm birth, primary C-section, and PIH when HbA1c ≥5.5% while HbA1c was significantly associated with PIH when HbA1c was 5.1-5.4% . In pre-pregnant underweight women with HbA1c 5.1-5.4%, HbA1c was significantly associated with primary C-section. HbA1c was significantly associated with macrosomia among women with inadequate GWG or excess GWG and HbA1c≥5.5%. In women with adequate GWG, there's significant association between HbA1c and PIH when HbA1c was 5.1-5.4% and ≥5.5% .

CONCLUSION

Conclusively, HbA1c at the time of diagnosis is significantly associated with macrosomia, preterm birth, PIH, and primary C-section in Chinese women with GDM.

Continuous Glucose Monitoring System Profile of Women Stratified Using Different Levels of Glycated Hemoglobin (HbA1c) in Early Pregnancy: A Cross-sectional Study

AIM

To evaluate the differences in the continuous glucose monitoring system (CGMS) profiles of women in early pregnancy stratified based on different HbA1c levels known to be predictive of gestational diabetes mellitus (GDM) at 24-28 weeks of gestation (≥ 5.2%) and adverse pregnancy outcomes (≥ 5.5%) in Indian women.

METHODS

We enrolled women at 8^+ 0 to 19^+ 6 weeks of gestation (early pregnancy), evaluated the glycaemic parameters of clinical interest using CGMS, and reported them per standard methodology proposed by Hernandez et al. WHO 2013 criteria were used for diagnosis of early GDM.

RESULTS

Ninety-six women were enrolled at 14.0 ± 3.2 weeks of gestation. Of these, 38 were found to have early GDM (diagnosed before 20 weeks of gestation) on evaluation. Of 96 women, 33 (34.4%) had HbA1c value ≥ 5.5% [11 (19.0%) with normoglycaemia and 22 (57.9%) with GDM]. The women with elevated HbA1c differed significantly from those with HbA1c < 5.5% for all evaluated parameters. The differences for overall women were > 10 mg/dl (0.56 mmol/l) for 1-h postprandial glucose (difference of 0.78 mmol/l), 2-h postprandial glucose (difference of 0.59 mmol/l), peak postprandial glucose (difference of 0.75 mmol/l), and 1-h postprandial glucose excursion (difference of 0.59 mmol/l). Of 58 women with normoglycaemia, 29 (50.0%) had an HbA1c value  ≥ 5.2%. In comparison, in the normoglycaemic group of women with and without HbA1c ≥ 5.2% (known to be predictive of future GDM), the results were significant for 1-h (difference of 0.44 mmol/l), 2-h (difference of 0.278 mmol/l), and peak postprandial glucose (difference of 0.35 mmol/l).

CONCLUSIONS

The results suggest that women with elevated HbA1c (≥ 5.5%) in early pregnancy significantly differ from those with HbA1c < 5.5% in all glycaemic parameters evaluated in this study, suggesting that HbA1c at this cut-off has a role to play in early pregnancy.

Continuous Glucose Monitoring System Profile of Women with Gestational Diabetes Mellitus Missed Using Isolated Fasting Plasma Glucose-Based Strategies Alternative to WHO 2013 Criteria: A Cross-Sectional Study

INTRODUCTION

The aim of the study was to evaluate the differences in the continuous glucose monitoring system (CGMS)-based glycemic parameters between women with normoglycemia and early gestational diabetes mellitus (GDM) identified on the basis of mild fasting plasma glucose elevation (FPG, 5.1-5.5 mmol/L) and/or post-load plasma glucose elevation (PLG, 1-h ≥ 10.0 mmol/L or 2-h ≥ 8.5 mmol/L).

METHODS

This cross-sectional study included women with singleton pregnancy (8⁺⁰ to 19⁺⁶ weeks of gestation) and normoglycemia or GDM per World Health Organization (WHO) 2013 criteria. We evaluated the glycemic parameters of clinical interest using blinded CGMS evaluation and reported them per standard methodology proposed by Hernandez et al. RESULTS: A total of 87 women (GDM, n = 38) were enrolled at 28.6 ± 4.5 years. Among women with GDM, 10 (26.3%) had isolated mild FPG elevation (5.1-5.5 mmol/L), 10 (26.3%) had isolated PLG elevation (1-h ≥ 10.0 mmol/L or 2-h ≥ 8.5 mmol/L), and 7 (18.4%) had a combination of both. The remaining 11 (28.9%) had elevated FPG (≥ 5.6 mmol/L) with or without PLG elevation. Thus, when an isolated FPG cutoff ≥ 5.6 mmol/L is used to diagnose GDM, 27 (71.0%) women would be perceived as normoglycemic. Such women had significantly higher CGMS parameters of clinical interest, such as 24-h mean glucose, fasting glucose, 1-h and 2-h postprandial glucose (PPG), 1-h PPG excursion, and peak PPG.

CONCLUSIONS

An isolated FPG threshold, especially the higher cutoff ≥ 5.6 mmol/L, can potentially miss a large proportion of women (nearly three-fourths) diagnosed with GDM per WHO 2013 criteria. Eventually, such women fare significantly differently from normoglycemic women in various CGMS parameters of clinical interest.

HbA1c at term delivery and adverse pregnancy outcome

Background

There are no obvious thresholds at which the risk of adverse pregnancy outcomes increases as a result of maternal hyperglycemia. HbA1c level which is representative of average blood glucose levels over the last 2–3 months is not as strongly predictive of adverse outcome compared to blood glucose values of oral glucose tolerance test. Data is sparse on the predictive value of HbA1c at term just prior to delivery on adverse outcome. We sought to evaluate HbA1c taken on admission for delivery at term on adverse outcomes of Cesarean delivery and large (≥ 90^th centile) for gestational age (LGA) infants.

Methods

A prospective cross-sectional study was conducted in a university hospital in Malaysia from December 2017-August 2018. 1000 women at term whose deliveries were imminent were enrolled. Blood were drawn and immediately sent for HbA1c analysis at our hospital laboratory. Primary outcomes were Cesarean delivery and LGA.

Results

On crude analyses, Cesarean births (vs. vaginal births) were associated with significantly higher HbA1c (%) levels 5.4[5.2–5.7] vs. 5.3[5.1–5.6] P =  < 0.001 but not for LGA vs. non-LGA 5.4[5.1–5.6] vs. 5.3[5.1–5.6] P = 0.17. After controlling for significant confounders identified on crude analysis (diabetes in pregnancy, parity, ethnicity, body mass index (BMI), previous cesarean, labor induction, Group B streptococcus (GBS) carriage and birth weight), HbA1c is independently predictive of Cesarean birth, adjusted odds ratio (AOR) 1.47 95% CI 1.06–2.06 P = 0.023 per HbA1c 1% increase. Following adjustment for significant confounders (BMI, predelivery anemia [hemoglobin < 11 g/dl] and GBS carriage), the impact of raised HbA1c level on LGA is AOR 1.43 95% CI 0.93–2.18 P = 0.101 per HbA1c 1% increase and non-significant.

Conclusion

Raised HbA1c level at term births in the general pregnant population is independently predictive of Cesarean delivery after adjustment for potential confounders including diabetes in pregnancy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-05000-7.

Gestational Diabetes Mellitus and Preeclampsia: Correlation and Influencing Factors

Gestational diabetes mellitus (GDM) and preeclampsia (PE) are common pregnancy complications with similar risk factors and pathophysiological changes. Evidence from previous studies suggests that the incidence of PE is significantly increased in women with GDM, but whether GDM is independently related to the occurrence of PE has remained controversial. GDM complicated by PE further increases perinatal adverse events with greater impact on the future maternal and offspring health. Identify factors associated with PE in women with GDM women, specifically those that are controllable, is important for improving pregnancy outcomes. This paper provides the findings of a review on the correlation between GDM and PE, factors associated with PE in women with GDM, possible mechanisms, and predictive markers. Most studies concluded that GDM is independently associated with PE in singleton pregnancy, and optimizing the treatment and management of GDM can reduce the incidence of PE, which is very helpful to improve pregnancy outcomes.