Maternal Glucose Concentration Influences Fetal Growth, Gestation, and Pregnancy Complications

Abstract

Although higher maternal glucose levels may augment fetal growth, they also are associated with complications of pregnancy when the mother is diabetic. The investigators reviewed data from 1990-1995 to discern the influence of postchallenge maternal glucose, if any, on pregnancy outcomes in 1157 nondiabetic American women who had singleton pregnancies culminating in a live-born infant. Participants were women less than 30 years of age who were enrolling for prenatal care. None of the participants had gestational diabetes or serious nonobstetrical problems. The study population included chiefly minority women; more than 85% used Medicaid to fund their pregnancy care. Maternal glucose levels could not be related to numerous risk factors that often are related to pregnancy outcome, such as parity and smoking, but non-Medicaid funding for prenatal care correlated with higher glucose concentrations, These women were older than the Medicaid recipients. Relatively high glucose levels also were found in women with an increased pregravid body mass index and greater skinfold thickness. Higher maternal glucose was associated with increased infant birth weight. After adjusting for many potential confounding factors, birth weights were about 50 g higher for gravidas with glucose levels of 99 to 130 mg/dl than for women whose levels were less than 99 mg/dl, and 200 g higher for those with concentrations exceeding 130 mg/dl. Increasing maternal plasma glucose levels correlated with a decreasing duration of gestation. The difference between gravidas with glucose levels exceeding 130 mg/dl and those whose levels were below 99 mg/dl was nearly 5 days. Higher glucose levels also were associated with a lower risk of fetal growth restriction and an increased risk of a large-for-gestational-age fetus, The risk of very preterm delivery was significantly increased (nearly 12-fold) when clinical chorioamnionitis was present and maternal glucose exceeded 13() mg/dl. These associations are consistent with a high maternal plasma glucose promoting transfer of nutrient to the fetus and increased fetal growth. In a poor urban population, insulin resistance might be a factor in the increased risk of very preterm delivery. It seems possible that higher but normal maternal plasma glucose levels predispose to, or act as a marker for, placental inflammation and subclinical infection.