Gestational Glucose Intolerance and Birth Weight–Related Complications

Abstract

OBJECTIVE: To evaluate the risks of large-for-gestational-age birth weight (LGA) and birth weight–related complications in pregnant individuals with gestational glucose intolerance, an abnormal screening glucose loading test result without meeting gestational diabetes mellitus (GDM) criteria. METHODS: In a retrospective cohort study of 46,989 individuals with singleton pregnancies who delivered after 28 weeks of gestation, those with glucose loading test results less than 140 mg/dL were classified as having normal glucose tolerance. Those with glucose loading test results of 140 mg/dL or higher and fewer than two abnormal values on a 3-hour 100-g oral glucose tolerance test (OGTT) were classified as having gestational glucose intolerance. Those with two or more abnormal OGTT values were classified as having GDM. We hypothesized that gestational glucose intolerance would be associated with higher odds of LGA (birth weight greater than the 90th percentile for gestational age and sex). We used generalized estimating equations to examine the odds of LGA in pregnant individuals with gestational glucose intolerance compared with those with normal glucose tolerance, after adjustment for age, body mass index, parity, health insurance, race and ethnicity, and marital status. In addition, we investigated differences in birth weight–related adverse pregnancy outcomes. RESULTS: Large for gestational age was present in 7.8% of 39,685 pregnant individuals with normal glucose tolerance, 9.5% of 4,155 pregnant individuals with gestational glucose intolerance and normal OGTT, 14.5% of 1,438 pregnant individuals with gestational glucose intolerance and one abnormal OGTT value, and 16.0% of 1,711 pregnant individuals with GDM. The adjusted odds of LGA were higher in pregnant individuals with gestational glucose intolerance than in those with normal glucose tolerance overall (adjusted odds ratio [aOR] 1.35, 95% CI 1.23–1.49, P<.001). When compared separately with pregnant individuals with normal glucose tolerance, those with either gestational glucose intolerance subtype had higher adjusted LGA odds (gestational glucose intolerance with normal OGTT aOR 1.21, 95% CI 1.08–1.35, P<.001; gestational glucose intolerance with one abnormal OGTT value aOR 1.77, 95% CI 1.52–2.08, P<.001). The odds of birth weight–related adverse outcomes (including cesarean delivery, severe perineal lacerations, and shoulder dystocia or clavicular fracture) were higher in pregnant individuals with gestational glucose intolerance with one abnormal OGTT value than in those with normal glucose tolerance. CONCLUSION: Gestational glucose intolerance in pregnancy is associated with birth weight–related adverse pregnancy outcomes. Glucose lowering should be investigated as a strategy for lowering the risk of these outcomes in this group.