The Association Between Low 50 g Glucose Challenge Test Values and Adverse Pregnancy Outcomes

The implications of low values on the 50 g glucose challenge test (GCT) in pregnancy are not clearly defined. Few studies have evaluated the influence of maternal low GCT values on obstetrical outcomes. This study aimed to compare pregnancy outcomes between women with low 50 g GCT values and those with normal values.

Women undergoing gestational diabetes mellitus screening at 24-28 weeks of gestational age between January 2010 and December 2016 were retrospectively evaluated. Women with multifetal pregnancies, prepregnancy type I or II diabetes, GCT performed before 24 or after 28 weeks of gestational age, and women undergoing multiple GCTs in the same pregnancy were excluded. Low GCT values and normal GCT values were defined as ≤85 mg/dL and 86-130 mg/dL, respectively.

Of 3875 screened subjects, 519 (13.4%) women were included in the low GCT group and 3356 (86.6%) in the normal GCT group. Low GCT women had a significantly higher rate of small for gestational age (SGA) infants than normal GCT women (10.8% vs. 7.9%, p = 0.02). Cesarean section and postpartum hemorrhage (PPH) were less frequent in low GCT women than in normal women (32.6% vs. 42.8%, p < 0.01 and 0.2% vs. 1.2%, p = 0.03, respectively). Low GCT women had a 1.38-fold increased risk of bearing SGA infants (95% confidence intervals: 1.01-1.88, p = 0.04).

Rate of SGA infants was significantly higher and cesarean delivery and PPH rates were significantly lower in women with low GCT values. Low GCT values were independently associated with an increased risk of SGA.