Despite treatment, HbA1c ≥ 37 mmol/mol in the first trimester is associated with premature delivery among South Asian women with gestational diabetes mellitus: a retrospective cohort study

PURPOSE

To examine the effects of first-trimester HbA1c (HbA1c-FT) ≥ 37 mmol/mol on preterm birth (PTB) and large-for-gestational-age (LGA) babies in a retrospective cohort of South Asian pregnant women with gestational diabetes (GDM).

METHODS

The cohort (n = 686) was separated into two groups based on HbA1c-FT values: Group A (n = 97) and Group B (n = 589), with values of 37-46 mmol/mol (5.5-6.4%) and < 37 mmol/mol (5.5%), respectively. HbA1c-FT's independent influence on PTB and LGA babies was examined using multivariable logistic regression in groups A and B women. The reference group (Group C) included 2031 non-GDM women with HbA1c-FT < 37 mmol/mol (< 5.5%). The effects of HbA1c-FT on PTB and LGA babies in obese women in Groups A, B, and C (designated as A-ob, B-ob, and C-ob, respectively) were re-analyzed using multivariable logistic regression.

RESULTS

Group A GDM women with greater HbA1c-FT had a higher risk for PTB (aOR:1.86, 95% CI:1.10-3.14) but not LGA babies (aOR:1.13, 95%: 0.70-1.83). The risk of PTB was higher for obese women in Group A-ob: aOR 3.28 [95% CI 1.68-6.39]. However, GDM women with normal HbA1c-FT exhibited no elevated risk for PTB: Groups B and B-ob had aORs of 1.30 (95% CI 0.86-1.98) and 1.28 (95% CI 0.88-1.85) respectively.

CONCLUSIONS

South Asian GDM women with prediabetic HbA1c FT; 37-46 mmol/mol (5.5-6.4%) are more likely to deliver preterm babies despite treatment, while the risk for LGA babies was the same as non-GDM women.

Intermediate hyperglycemia in early pregnancy: A South Asian perspective

“Intermediate hyperglycemia in early pregnancy (IHEP)” refers to mild hyperglycemia detected before 24 gestational weeks (GW), satisfying the criteria for the diagnosis of gestational diabetes mellitus. Many professional bodies recommend routine screening for “overt diabetes” in early pregnancy, which identifies a significant number of women with mild hyperglycemia of undetermined significance. A literature search revealed that one-third of GDM women in South Asian countries are diagnosed before the conventional screening period of 24 GW to 28 GW; hence, they belong in the IHEP category. Most hospitals in this region diagnose IHEP by oral glucose tolerance test (OGTT) using the same criteria used for GDM diagnosis after 24 GW. There is some evidence to suggest that South Asian women with IHEP are more prone to adverse pregnancy events than women with a diagnosis of GDM after 24 GW, but this observation needs to be proven by randomized control trials. Fasting plasma glucose is a reliable screening test for GDM that can obviate the need for OGTT for GDM diagnosis among 50% of South Asian pregnant women. HbA1c in the first trimester predicts GDM in later pregnancy, but it is not a reliable test for IHEP diagnosis. There is evidence to suggest that HbA1c in the first trimester is an independent risk factor for several adverse pregnancy events. Further research to identify the patho-genetic mechanisms behind the fetal and maternal effects of IHEP is strongly recommended.

Establishing Trimester-Specific Haemoglobin A1c Reference Intervals in Pregnant Women: A retrospective study of healthy South Asian women with normal pregnancy outcomes

Objectives

This study aimed to define trimester-specific haemoglobin A1c (HbA1c) reference intervals in healthy, pregnant South Asian women.

Methods

This retrospective study was conducted at St. Stephen's Hospital, Delhi, India, between January 2011 and December 2016. Healthy pregnant women were compared to a control group of healthy non-pregnant women. Pregnant participants had term deliveries of babies with appropriate gestational weights. The HbA1c levels were calculated in terms of non-parametric 2.5 and 97.5 percentiles for women in first (T1), second (T2) and third (T3) trimester groups. Statistical tests were used to obtain the normal HbA1c reference values and were considered significant when P <0.05.

Results

This study included a total of 1,357 healthy pregnant women and a control group of 67 healthy, non-pregnant women. Pregnant women had a median HbA1c of 4.8% (4-5.5%) or 32 mmol/mol (20-39 mmol/mol); non-pregnant women had a median HbA1c of 5.1% (4-5.7%) or 29 mmol/mol (20-37 mmol/mol; P <0.001). The HbA1c levels for the T1, T2 and T3 groups were 4.9% (4.1-5.5%) or 30 mmol/mol (21-37 mmol/mol), 4.8% (4.5-5.3%) or 29 mmol/mol (20-34 mmol/mol) and 4.8% (3.9-5.6%) or 29 mmol/mol (19-38 mmol/mol), respectively. The HbA1c values were significant when comparing T1 versus T2 (P <0.001), T1 versus T3 (P = 0.002) and T1 versus the non-pregnant group (P = 0.001). However, T2 versus T3 was not significant (P = 0.111).

Conclusion

Compared to non-pregnant women, HbA1c levels were lower in pregnant women, despite women in the T2 and T3 groups having a higher body mass index than the women in the T1 and non-pregnant groups. Further research is recommended to understand the factors responsible and validate these findings.

Is HbA1c in the first trimester associated with adverse outcomes among pregnant Asian Indian women without gestational diabetes?

AIMS

The aim of this study is to determine the association of elevated HbA1c in the first trimester (HbA1c-FT) with adverse events among pregnant Asian Indian women without gestational diabetes (GDM).

METHODS

This retrospective cohort study included 1618 pregnant women who delivered at a single urban tertiary care center and had HbA1c-FT estimation between January 2011 and September 2017. Those with GDM according to a 75-g OGTT after 24 gestational weeks were excluded. Multivariable logistic regression models assessed the association between elevated HbA1c-FT and adverse events.

RESULTS

At a cutoff of ≥37 mmol/mol (5.5%), HbA1c-FT was associated with preterm birth at <37 gestational weeks (adjusted odds ratio (OR) 2.10, 95% CI 1.11-3.98). There was a continuum of risk for primary caesarean delivery with higher HbA1c-FT levels (adjusted OR per 5-mmol/mol (0.5%) increase in HbA1c-FT for primary caesarean delivery: 1.27, 95% CI 1.06-1.52). In the crude analysis, gestational hypertension was associated with HbA1c-FT, but not after adjustment for confounding factors. HbA1c-FT was not associated with other adverse events (macrosomia, large for gestational age babies, or other neonatal complications).

CONCLUSIONS

Even without GDM, the results suggest an association of HbA1c-FT with preterm birth and primary caesarian delivery among Asian Indian women.

Prevalence of 'Hyperglycemia in pregnancy' remained stable between 2006 and 2015, despite rise in conventional risk factors: A hospital based study in Delhi, North India

AIMS

Between 2006 and 2015, the trends in prevalence of Hyperglycemia in pregnancy (HIP); Gestational diabetes (GDM), Diabetes in Pregnancy (DIP), Pre existing diabetes (PDM) and GDM risk factors were studied in 30,692 pregnancies among Asian Indian women.

METHODS

GDM (n = 4089) and DIP (n = 259) diagnoses were by 75 g OGTT, while PDM (n = 103) was identified by ICD code O24. Women with DIP and PDM were grouped together as pre-gestational diabetes (PGDM n = 362). Crude and age-adjusted prevalence trend analysis by Poisson and Jointpoint regression models respectively, were done in GDM and PGDM groups.

RESULTS

During study years, the GDM prevalence by WHO 1999 and modified IADPSG criteria, showed decreasing and static trends respectively, while PGDM prevalence remained static. In a subgroup of 2560 women, mean BMI increased from 24.12 ± 4.16 in year 2011 to 25.18 ± 4.7 Kg/m² in 2015 (p < 0.014), but this rise had no impact on GDM prevalence. GDM risk factors; maternal age, gravidity ≥3, previous GDM and abortion, high income, diabetes and hypertension in family, were higher in 2011-2015 than in 2006-2010 period. On multivariate analysis, BMI was not an independent GDM risk factor.

CONCLUSION

Despite rise in conventional GDM risk factors, HIP prevalence was static for a decade among pregnant Asian Indian women.