Maternal Obesity and Small for Gestational Age Infants

Study Summary

The purpose of this retrospective pilot study is to address the effect that obesity, in the absence of other comorbidities, has on birth weight. We wish to determine if obesity is a risk factor for small for gestational age (SGA) or intrauterine growth restricted (IUGR) infants in our clinic population. There have been many studies linking maternal obesity with fetal macrosomia, defined as fetal birth weight greater than 4500 grams. However, we have noted that a percentage of our obese patient population has delivered either an SGA or IUGR infant. SGA refers to a constitutionally small infant weighing less than the 10th percentile for age. This refers to a genetically normal infant. IUGR refers to a fetus whose growth has been restricted by influences other than normal genetics. Our study population will consist of all women over the age 18 who delivered a term infant either by vaginal delivery or cesarean section at Tulsa Regional Medical Center between July 1st 2004 and December 31st 2005. The diagnosis of obesity will be based upon a Body Mass Index (weight in kilograms/height in meters squared) of thirty or greater. We will look at the infant birth weight as recorded in the patient's chart. We will define SGA or IUGR as birth weight less than the 10th percentile for gestational age as defined previously. The control group will consist of women meeting the same criteria except they will have a BMI less than thirty but greater than 19.8 as low maternal weight is also a risk factor for IUGR. We will compare the average birth weight and the rates of SGA/IUGR infants between the two groups and analyze using the chi-squared method of analysis.