Rates of obesity have increased since the 1980s and now an estimated 40% of reproductive aged women are obese. Pregnant patients who are obese are at increased risk of related complications such as excessive pregnancy weight gain, pre-gestational and gestational diabetes. This in turn increases the risk of fetal macrosomia and large for gestational age (LGA) infants. The degree to which these maternal conditions affect fetal growth is starting to be better understood but there are likely overlapping contributions. Previous studies have demonstrated a relationship between abnormal fetal growth curves and obesity and gestational diabetes (GDM) separately. The purpose of this study is to investigate in an obese population without major medical comorbidities, the effect of glucose tolerance on fetal growth trajectories. 

For this retrospective cohort study, chart review will be performed to gather de identified data for analysis. The study population will include patients with class III obesity stratified by glucose tolerance defined as normal glucose tolerance, impaired glucose tolerance, or GDM. Inclusion criteria are a singleton gestation, a late third trimester ultrasound at 34 weeks or beyond, delivery at 34 weeks gestation or beyond, class III obesity (BMI ≥40 kg/m2) at first prenatal visit or transfer of care visit , a dating ultrasound before 22 weeks gestation, and completion of glucose tolerance testing with 50-gram 1-hour glucose screen and/or 100-gram 3-hour oral glucose tolerance test. Exclusion criteria included multiple gestation, stillbirth, known major fetal anomaly, major maternal comorbidities or early preterm delivery (<34wks gestation). Primary outcomes are the difference in mean/median abdominal circumference and estimated fetal wight on a late third trimester ultrasound adjusted for gestational age. Secondary outcomes include EFW and AC trajectories, LGA infants and macrosomia, other biometric measures (HC, BPD, FL, HC/AC), an association of fetal growth with glycemic control in GDM, rate of individual maternal outcomes, and rate of composite neonatal outcomes. Continuous variables will be analyzed using t-tests, ANOVA or Kruskal-Wallis tests as appropriate. Categorical variables will be analyzed using chi-square or Fisher’s exact test as appropriate. Linear regression techniques will be utilized to evaluate difference in late third trimester fetal growth parameters with models adjusted for potential confounding variables.

Data collection ongoing