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

Reference range for glycated haemoglobin in full term non diabetic pregnant women: a multicentric cross sectional study

BACKGROUND

There are no large studies to define the normal value of glycated haemoglobin (HbA1c) measured in full term pregnant women measured at the time of delivery.

RESEARCH DESIGN AND METHODS

The study was conducted at three government hospitals in South India. Clinical data, maternal blood sample and foetal cord blood sample were collected from women admitted for safe confinement. Mean (± SD) of HbA1c in participants with no known diabetes (gestational or pregestational) or any complications (maternal or fetal) is described, 2.5th-97.5th centile reference range was derived.

RESULTS

From 3 centres, 2004 women participated in the study. Data from 1039 participants who had no history of diabetes or any maternal or fetal complication were used to determine the reference range for HbA1c at term pregnancy. The mean HbA1c in subjects devoid of diabetes and its known complications was 5.0 (± 0.39) %. The reference range for normal HbA1c at term in these women was found to be 4.3-5.9%. Maternal HbA1c at term pregnancy in non-diabetic pregnant women is associated with pre-pregnancy BMI, maternal age and 2-h plasma glucose level of 2nd trimester oral glucose tolerance test (OGTT).

CONCLUSIONS

The mean HbA1c at term pregnancy in non-diabetic women admitted for safe confinement is 5.00 (± 0.39) %. An HbA1c of 5.9% or more at term should be considered abnormal and women with such a value may be kept at a close surveillance for development of diabetes.

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.

Post-load glucose is a stronger predictor of adverse pregnancy outcomes than first-trimester HbA1c in women without gestational diabetes

AIMS/INTRODUCTION

A debate exists on the relation of adverse pregnancy outcomes with glycemic levels in early pregnancy. We aimed to investigate the association of maternal characteristics including post-load glucose and first-trimester HbA1c test results with adverse pregnancy outcomes in women without gestational diabetes mellitus.

MATERIALS AND METHODS

A dataset (January 2011 and September 2017) from a hospital prenatal clinic was explored to find the important predictors of adverse pregnancy outcomes using maternal characteristics and glucose assessments in mothers without gestational diabetes. We used two machine learning algorithms to capture nonlinearity in selecting important maternal characteristics and developed predictive models for each outcome. In total, 1,618 pregnant women were included in the analytic dataset with a mean (SD) age of 26.8 (3.5) years and gravida of 1.7 (0.9).

RESULTS

Important associations were detected between maternal features and primary cesarean section, fetal distress, premature rupture of membranes, macrosomia, small or large for gestational age, APGAR <7 at 1 or 5 min, hyperbilirubinemia, and poly- or oligo-hydramnios. Overall, the predictive models showed good performance and large areas under the curves (0.732, 0.765, 0.646, 0.651, 0.730, 0.646, 0.684, 0.716, and 0.678, respectively). Specifically, they had high positive likelihood ratios.

CONCLUSIONS

High glucose levels were associated with adverse pregnancy outcomes. Post-load glucose was the most reliable test for predicting the outcomes. Overall, fasting blood sugar was of more predictive value than HbA1c. Our study showed that further research should account for the nonlinearity and interactions inherent in the data.