The relationship between maternal glycemia and perinatal outcome

Abstract

Objective: To examine the relationship between varying degrees of maternal hyperglycemia and pregnancy outcomes.

Methods: This was a secondary analysis of a treatment trial for mild gestational diabetes including four cohorts: 1) 473 women with untreated mild gestational diabetes; 2) 256 women with a positive 50-g screen and one abnormal oral glucose tolerance test (OGTT) value; 3) 675 women with a positive screen and no abnormal OGTT values; and 4) 437 women with a normal 50-g screen. Groups were compared by test of trend for a composite perinatal outcome (neonatal hypoglycemia, hyperbilirubinemia, elevated cord C-peptide level, and perinatal trauma or death), frequency of large for gestational age neonates, shoulder dystocia, and pregnancy-related hypertension. Three-hour OGTT levels (fasting, 1-, 2-, and 3-hour) levels were divided into categories and analyzed for their relationship to perinatal and maternal outcomes.

Results: There were significant trends by glycemic status among the four cohorts for the composite and all other outcomes (P<.001). Analysis for trend according to OGTT categories showed an increasing relationship between fasting and all postload levels and the various outcomes (P<.05). Fasting glucose 90 mg/dL or greater and 1 hour 165 mg/dL or greater were associated with an increased risk for the composite outcome (odds ratios and 95% confidence intervals of 2.0 [1.03–4.15] and 1.46 [1.02–2.11] to 1.52 [1.08–2.15] for the fasting and 1 hour, respectively). A 1 hour glucose 150 mg/dL or greater was associated with an increased risk for large for gestational age (odds ratios, 1.8 [1.02–3.18] to 2.35 [1.35–4.14]); however, 2- and 3-hour glucose levels did not increase the risk for the composite or large for gestational age until well beyond current gestational diabetes diagnostic thresholds.

Conclusion: A monotonic relationship exists between increasing maternal glycemia and perinatal morbidity. Current OGTT criteria require reevaluation in determining thresholds for the diagnosis and treatment of gestational diabetes.

Level of evidence: II

Figure 1

Frequencies of various outcomes according to glucose groupings. A = 50 gm screen <120 mg/dl, B = 50 gm screen ≥135mg/dl with normal OGTT, C = 50 gm screen ≥135 mg/dl with one abnormal OGTT value, D = GDM (two abnormal OGTT values). Number of Subjects: Composite: A: 407 B: 626 C: 238 D: 440 LGA: A: 421 B: 652 C: 251 D: 454 C-Peptide: A: 365 B: 549 C: 211 D: 403 Shoulder Dystocia: A: 423 B: 653 C: 252 D: 455 Gestational Hypertertension: A: 423 B: 653 C: 252 D: 455

Figure 2

Comparisons of outcomes between glucose groups. Abnormal versus Normal 50 Gram Screen: Composite: 279/864 (Abnormal Screen), 105/407 (Normal Screen) LGA: 95/903 (Abnormal Screen), 28/421 (Normal Screen) C-Peptide (C-Pep): 119/760 (Abnormal Screen), 45/365 (Normal Screen) Shoulder Dystocia (ShD): 17/905 (Abnormal Screen), 3/423 (Normal Screen) Gestational Hypertension/Preeclampsia (Gest.HTN/Preec): 83/905 (Abnormal Screen), 31/423 (Normal Screen) Abnormal Screen versus GDM: Composite: 279/864 (Abnormal Screen), 163/440 (GDM) LGA: 95/903 (Abnormal Screen), 66/454 (GDM) C-Peptide (C-Pep): 119/760 (Abnormal Screen), 92/403 (GDM) Shoulder Dystocia (ShD): 17/905 (Abnormal Screen), 18/455 (GDM) Gestational Hypertension/Preeclampsia (Gest.HTN/Preec): 83/905 (Abnormal Screen), 62/455 (GDM) GDM versus 1 Abnormal OGTT Value: Composite: 163/440 (GDM), 75/238 (1 Abnormal OGTT) LGA: 66/454 (GDM), 28/251 (1 Abnormal OGTT) C-Peptide (C-Pep): 92/403 (GDM), 40/211 (1 Abnormal OGTT) Shoulder Dystocia (ShD): 18/455 (GDM), 6/252 (1 Abnormal OGTT) Gestational Hypertension/Preeclampsia (Gest.HTN/Preec): 62/455 (GDM), 29/252 (1 Abnormal OGTT)

Figure 3. Percentage of infants with LGA by OGTT Glucose Level

Fasting OGTT (mg/dL): (1) < 75, (2) 75-79, (3) 80-84, (4) 85-89, (5) 90-94 1 Hour OGTT (mg/dL): (1) < 150, (2) 150-164, (3) 165-179, (4) 180-194, (5) ≥ 195 2 Hour OGTT (mg/dL): (1) <125, (2) 125-139, (3) 140-154, (4) 155-169, (5) ≥ 170 3 Hour OGTT (mg/dL): (1) < 110 (2) 110-124, (3) 125-139, (4) 140-154, (5) ≥ 155.