Does anterior abdominal wall thickness reflect glycaemic control and can it predict birthweight?

Abstract

AND CAN IT PREDICT BIRTHWEIGHT? NOIRIN RUSSELL, CECELIA MULCAHY, MICHAEL FOLEY, FIONNUALA MCAULIFFE, University College Dublin, Dublin, Ireland, National Maternity Hospital, Holles St., Dublin, Ireland, University College Dublin, Obstetrics and Gynaecology, Dublin, Ireland, University College Dublin, Obstetrics & Gynecology, Dublin, Ireland OBJECTIVE: Ultrasound prediction of birthweight is an inaccurate science especially at the extremes of growth. In utero measurements of fetal anthropometric measurements have been used in an attempt to increase accuracy. The aim of the study is to determine if there is an association between third trimester anterior abdominal wall thickness and birth weight and also whether booking HbA1C in type 1 diabetic pregnancy is associated with an increased fetal anterior abdominal wall thickness. STUDY DESIGN: This is a prospective study with institutional ethics approval and written maternal consent. A measurement of the fetal anterior abdominal wall (AAW) was taken at the traditional abdominal circumference view, 2-3 cm lateral to the cord insertion, and included fetal skin and subcutaneous tissue. Measurements were recorded at 33-37 week’s gestation in 167 patients. Birth weight and birth weight centile was recorded. RESULTS: Of 167 measurements taken, 90 were in fetuses of type 1 diabetic mothers, 54 in fetuses of gestational diabetic mothers, 15 in fetuses of nondiabetic mothers and 8 in fetuses of type 2 diabetic mothers. Booking HbA1c in the pregestational diabetic population correlated positively with third trimester AAW measurements (p!0.05). Third trimester anterior abdominal wall thickness correlated positively with birth weight (p!0.01) and with birth weight centile at delivery (p!0.001). Third trimester AAW measurements are significantly higher in babies with a birth weight O/=90th centile compared to those with a birth weight less than the 90th centile (5.4C/ 1.1mm vs. 4.9C/ 1.2 p!0.05). CONCLUSION: Poorer periconceptual glycaemic control results in thickened fetal anterior abdominal wall thickness in the third trimester in type 1 diabetes. An AAW measurement of greater than 5mm in the third trimester may help to identify fetuses at risk of macrosomia.