Objective. The purpose of this study was to compare the accuracy of traditional 2-dimensional sonographically estimated fetal weight (EW2D) with 3-dimensional volume-based estimated fetal weight (EW3D) and to evaluate the relationship between fetal limb volume, birth weight, and markers of neonatal adiposity. Methods. Fifty singleton pregnancies at 32 to 42 weeks' gestation underwent sonographic evaluation within 48 hours of delivery. We compared the accuracy of the EW2D and EW3D in the prediction of birth weight. The Ponderal index, sum of all skin fold measurements, estimated neonatal fat mass, and percent body fat were calculated. Paired t tests, simple regression analyses, a χ 2 test, and the Steiger z test were used where appropriate. P < .05 was considered significant. Results. The mean birth weight ± SD was 3130 ± 589 g at 38.8 ± 2.1 weeks. The EW2D (r 2 = 0.66) and EW3D (r 2 = 0.76) estimates were both correlated with birth weight. The birth weight and neonatal fat mass were more highly correlated with the sonographically based thigh volume (r 2 = 0.67 and 0.61) than femur length (r 2 = 0.41 and 0.37). The mean percent error between EW2D and birth weight was larger (-3.3% ± 11.6%) than the mean percent error of EW3D (0.7% ± 9.2%; P = .0004). Abbreviations EW3D, 3-dimensional volume-based estimated fetal weight; EW2D, 2-dimensional sonographically estimated fetal weight; 3D, 3-dimensional; 2D, 2-dimensional bstetric management is often based on knowledge of fetal weight. With the advent of ultrasound, such estimates were no longer crude, and estimates of fetal size became more consistent. As measurements became more refined, techniques have evolved that enable identification of adequate and altered fetal growth. For the past 2 decades, sonographic estimation of gestational age and fetal weight has relied on a series of formulas derived from biometric measurements of the fetus, including the fetal head, abdomen, and femur. 1 These estimates are not highly accurate, with 86.5% of estimates being within 15% of actual birth weight. 1 The relationship between neonatal anthropometric measurements and body composition has been studied. 2 Although neonatal fat constitutes 14% of total birth weight, it accounts for 46% of the variance in birth weight. 3 Although fetal head and femur measurements do not allow for discrimination between lean and nonlean fetuses, the abdominal circumference measurement does include Conclusions

OBJECTIVE: To assess the impact of birth simulation training on medical student comfort, confidence and anxiety in performing a delivery, and knowledge of normal labor. METHODS: In this prospective study of 3rd-year medical students during their 4-week inpatient clinical experience, student groups were randomly assigned to “traditional” teaching versus traditional plus additional “simulation” teaching. All students were immersed in clinical experiences in the delivery room after an initial group education session regarding normal labor and delivery mechanisms and procedures. The group assigned to “simulation” underwent additional supervised simulation training for normal delivery and delivery complications. All groups underwent a pretest before training and a posttest on completion of their clinical rotation. Evaluated variables included: confidence and anxiety regarding performing a delivery; comfort controlling the head, shoulders and body during delivery; comfort in delivering a placenta; and knowledge of cardinal movements and stages of labor. Statistical analyses were accomplished using Pearson χ2 analysis and Student's T tests. RESULTS: Sixty students participated. Overall, both traditional teaching and simulation groups demonstrated significant improvements in their scores regarding measures of comfort, anxiety, and knowledge between the pre- and posttests (P≤0.05). However, comparison of posttest responses did not reveal those undergoing additional simulation training to have higher comfort or confidence in performing a vaginal delivery (P>.05), or have lower anxiety at being involved in a vaginal delivery (P>.05). Similarly, knowledge about the cardinal movements of labor and stages of labor at the posttest were similar between groups (P>.05). CONCLUSION: In the context of an inpatient clinical rotation in which student comfort, confidence, anxiety, and knowledge regarding vaginal delivery improved significantly with traditional teaching, additional simulation training was not associated with improved outcomes.