It's not just the abdominal circumference: glycemic control still matters

Abstract

A fetal abdominal circumference (AC) <75th percentile has been proposed as a marker indicating that gestational diabetes (GDM) can be managed with diet without requiring insulin therapy. We sought to determine whether the quality of maternal glycemic control modifies this equation. Women with GDM (n = 574) and with fasting blood glucose <105 mg/dL were managed during pregnancy with diet alone (n = 348) or diet and insulin (n = 226). Glucose concentrations were self-monitored 7 times a day using memory-equipped reflectance meters and therapy was aimed at maintaining pre-prandial glucose at <95 mg/dL and 2-hour post-prandial glucose at <120 mg/dL. Subjects were classified as having good (mean glucose ≤105 mg/dL) or poor (mean glucose >105 mg/dL) glycemic control. Fetal AC was measured sonographically at 25-32 weeks and classified as <75th or ≥75th percentile for gestational age. Birthweight ≥90th% was considered large for gestational age (LGA). Statistical analysis was performed using chi-square. The rate of LGA was 13.0% among women who achieved good control (n = 384) and 22.1% among those who had poor control (n = 190) (P<.005; OR = 1.91, 95% CI = 1.2-2.9). When good control was achieved, there was no association between AC and LGA, whether treatment was with diet or with insulin. However, in the presence of poor control, a large AC was associated with a twofold increase in the rate of LGA in both insulin- and diet-controlled women. These findings are summarized in the Tables below. The association of fetal AC at 25-32 weeks with LGA depends on the quality of maternal glycemic control. Both diet and insulin therapy are effective in preventing LGA regardless of the fetal AC, providing good maternal glycemic control can be achieved.Tabled 1AC <75%AC ≥75%PGood control LGA (diet)12.5%11.1%NS LGA (insulin)14.1%12.5%NSPoor control LGA (diet)23.4%53.8%<.05 LGA (insulin)13.9%27.3%NS Open table in a new tab