Elevated fetal growth during the antenatal period is associated with maternal obesity class
Authors: Gordon Felicia , Liddell Shelby , Bofill James , Coats Laura 
Published: May 2023

Obesity is characterized as a body mass index (BMI) >30.0 kg/m2. Obesity is further classified into Obesity Class 1 (BMI 30-34.9 kg/m2), Obesity Class 2 (BMI 35-39.9 kg/m2), and Obesity Class 3 (BMI ≥ to 40 kg/m2). In Mississippi, over 43% of women of childbearing age (18-44 years old) are obese. Numerous studies support the concept that in-utero exposure to a maternal obesogenic environment promotes fetal macrosomia (fetal growth above average per gestational age) and program offspring to metabolic complications throughout their lifespan. Yet, the association of obesity class on fetal growth and development is not well defined. Thus, we tested the hypothesis that increases in maternal obesity class promote excess fetal growth in offspring from obese mothers during the antenatal period. This study evaluated ultrasounds of pregnant women (n= 568) at the University of Mississippi Medical Center (UMMC) from 2019-2020. Women were evenly divided by BMI class (Normal, Obesity Class 1, Obesity Class 2, and Obesity Class 3). Obesity Class 3 was limited to a BMI of 40-44.9 kg/m2. Women were of reproductive age (18-44 years old). Maternal and fetal measurements were assessed at 1 time point at a routine ultrasound visit between 18-38 weeks gestation. Average maternal age was 28.27±6.15 years. Average gestational age of offspring was 23.91±5.41 weeks. Estimated fetal weight did not differ between Normal, Obesity Class 1, and Obesity Class 2. Estimated fetal weight was significantly increased in Obesity Class 3 (854.50±677.00 g) ( p<0.05) vs. Normal (401.10±159.60 g) ( p<0.05), Obesity Class 1 (445.9±202.3 g) ( p<0.05), and Obesity Class 2 (532.5±348.3 g) ( p<0.05). Estimated fetal weight by offspring gender per BMI Class did not differ. Abdominal circumference, a predictor of fetal growth, was only significantly increased in Obesity Class 2 (47.85±28.58 mm) vs Normal (37.15±24.85 mm) ( p<0.05). We also evaluated abdominal circumference by offspring gender per BMI class. Abdominal circumference was significantly reduced in Normal females (25.90±20.79 mm) vs. Normal males (44.67±24.60 mm) ( p<0.05), Obesity Class 1 females (48.25±27.79 mm) ( p<0.05), Obesity Class 2 males (45.26±27.74 mm) ( p<0.05) and females (48.31±30.03 mm) ( p<0.05), and Obesity Class 3 males (52.18±33.29 mm) ( p<0.05). These data indicate that severe obesity (BMI ≥ to 40 kg/m2) increases risk for fetal macrosomia, placing offspring at risk for metabolic disorders throughout their lifespan. Females exhibit greater increases in abdominal circumference by obesity class which suggests that female offspring are at greater risk of excess gestational growth in obesogenic environments compared to male counterparts. Yet, these data do not represent offspring weight or abdominal circumference at birth. Further studies are warranted to determine the influence of obesity on fetal growth after 38 weeks gestation and the placental mechanisms associated with fetal growth and development in maternal obesity. UMMC Department of Obstetrics and Gynecology This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.