Post-load glucose more reliable test than HbA1c for predicting adverse pregnancy outcomes: Study

The study suggests that post-load plasma glucose (PLPG) provides greater reliability than HbA1c in assessing APO risk.

Adverse outcomes of gestational diabetes mellitus (GDM) can impact both maternal and fetal health. Hyperglycemia is suggested to be the underlying cause of several GDM complications. However, a screening of pregnant women for maternal hyperglycemia showed a spectrum of glucose intolerance.

Studies have investigated the association of hemoglobin A1c (HbA1c), fasting plasma glucose, insulin resistance, and oral glucose tolerance with adverse obstetric outcomes. Debate exists on the relationship of adverse pregnancy outcomes with glycemic levels in early pregnancy. In particular, the association of maternal blood glucose concentrations with adverse pregnancy outcomes (APO) risk in women with GDM remains controversial.

Against the above background, Elham Toghraee, Shiraz University of Medical Sciences, Shiraz, Iran, and colleagues 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 GDM.

For this purpose, the researchers explored a dataset (January 2011 and September 2017) from a hospital prenatal clinic to find the important predictors of adverse pregnancy outcomes using maternal characteristics and glucose assessments in mothers without gestational diabetes.

The investigators used two machine learning algorithms to capture nonlinearity in selecting important maternal characteristics and developed predictive models for each outcome. 1,618 pregnant women were included in the analytic dataset with a mean age of 26.8 years and gravida of 1.7.

The study revealed the following findings:

• 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.
• 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.

In conclusion, the findings showed differences in the predictive power of post-load glucose and first-trimester HbA1c test results for adverse pregnancy outcomes. Overall, PLPG1 or PLPG2 showed greater importance scores than hemoglobin A1c for all outcomes. Furthermore, fasting blood sugar outranked HbA1c in most of the importance ratings.

"We also recommend that future studies of pregnancy outcomes use data analysis techniques capable of capturing nonlinearity and complex interactions," the researchers wrote.

Reference:

Rajabi, S. K., Toghraee, E., & Nejatipour, G. Post-load glucose is a stronger predictor of adverse pregnancy outcomes than first-trimester HbA1c in women without gestational diabetes. Journal of Diabetes Investigation. https://doi.org/10.1111/jdi.14181