title: Baseline HbA1c to Identify High-Risk Gestational Diabetes: Utility in Early vs Standard Gestational Diabetes.
abstract: The increasing prevalence of gestational diabetes mellitus (GDM) necessitates risk stratification directing limited antenatal resources to those at greatest risk. Recent evidence demonstrates that an early pregnancy glycated hemoglobin (HbA1c ≥5.9% (41 mmol/mol) predicts adverse pregnancy outcomes.
  
  
  
  To determine the optimal HbA1c threshold for adverse pregnancy outcomes in GDM in a treated multiethnic cohort and whether this differs in women diagnosed <24 vs ≥24 weeks' gestation (early vs standard GDM).
  
  
  
  This was a retrospective cohort study undertaken at the Royal Prince Alfred Hospital Diabetes Antenatal Clinic, Australia, between 1991 and 2011.
  
  
  
  Pregnant women (N = 3098) underwent an HbA1c (single-laboratory) measurement at the time of GDM diagnosis. Maternal clinical and pregnancy outcome data were collected prospectively.
  
  
  
  The association between baseline HbA1c and adverse pregnancy outcomes in early vs standard GDM.
  
  
  
  HbA1c was measured at a median of 17.6 ± 3.3 weeks' gestation in early GDM (n = 844) and 29.4 ± 2.6 weeks' gestation in standard GDM (n = 2254). In standard GDM, HbA1c >5.9% (41 mmol/mol) was associated with the greatest risk of large-for-gestational-age (odds ratio [95% confidence interval] = 2.7 [1.5-4.9]), macrosomia (3.5 [1.4-8.6]), cesarean section (3.6 [2.1-6.2]), and hypertensive disorders (2.6 [1.1-5.8]). In early GDM, similar HbA1c associations were seen; however, lower HbA1c correlated with the greatest risk of small-for-gestational-age (P trend = 0.004) and prevalence of neonatal hypoglycemia.
  
  
  
  Baseline HbA1c >5.9% (41 mmol/mol) identifies an increased risk of large-for-gestational-age, macrosomia, cesarean section, and hypertensive disorders in standard GDM. Although similar associations are seen in early GDM, higher HbA1c levels do not adequately capture risk-limiting utility as a triage tool in this cohort.
authors: Diabetes Centre.|Sydney Medical School and.
authors: Arianne N
authors: AN
authors: Sweeting
authors: Diabetes Centre.|Sydney Medical School and.
authors: Glynis P
authors: GP
authors: Ross
authors: Department of High Risk Obstetrics, and.|Discipline of Obstetrics, Gynaecology and Neonatology, University of Sydney, Sydney, New South Wales 2006, Australia.
authors: Jon
authors: J
authors: Hyett
authors: Diabetes Centre.|Sydney Medical School and.
authors: Lynda
authors: L
authors: Molyneaux
authors: Endocrinology, Royal Prince Alfred Hospital, Sydney, New South Wales 2050, Australia; and.
authors: Kris
authors: K
authors: Tan
authors: Diabetes Centre.|Sydney Medical School and.
authors: Maria
authors: M
authors: Constantino
authors: Diabetes Centre.
authors: Anna Jane
authors: AJ
authors: Harding
authors: Diabetes Centre.|Sydney Medical School and.
authors: Jencia
authors: J
authors: Wong
mesh_terms: D000328:Adult; D001315:Australia / Q000453:epidemiology; D015415:Biomarkers / Q000097:blood*; D001724:Birth Weight; D001786:Blood Glucose / Q000032:analysis; D002585:Cesarean Section; D016640:Diabetes, Gestational / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000453:epidemiology*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011256:Pregnancy Outcome; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human