Accuracy of third trimester ultrasound in predicting neonata
This study evaluates the accuracy of third-trimester ultrasound in predicting birth weight in patients with inflammatory bowel disease (IBD) using the gestation-adjusted projection (GAP) method.

A retrospective cohort study including pregnant patients with IBD who had third-trimester ultrasounds and delivered at a single institution. Controls included pregnant patients without IBD seen during the study period with third-trimester ultrasounds.

Correlation plots of GAP birthweight and actual birth weight (AB) were created for IBD-positive cases, IBD-negative controls, and IBD-positive cases with and without prior abdominal surgery. GAP predicted birthweight error was calculated for cases and controls. Univariable linear regression models estimated the association between predicted birthweight and AB.

320 patients were included. Cases were more likely to be older, white, and have a lower BMI.

- Correlation plots of GAP birthweight and AB showed linear correlations in cases, controls, cases with and without prior surgery.

- GAP birthweight was significantly associated with AB in controls and cases in univariable linear regression models.

- No significant difference was found between the parameter estimates of the two models. GAP birthweight remained significantly associated with AB in a multivariable linear regression model.

- There were no significant differences between GAP predicted birthweight error between controls and cases and between cases without and with prior surgery.

The accuracy of fetal biometry in the third trimester for predicting actual birth weight was equivalent between patients with and without IBD and those with prior abdominal surgery.

European Journal of Obstetrics & Gynecology and Reproductive Biology