Factors affecting the accuracy of estimated fetal weight in small for gestational age (SGA) fetuses

Aims: To identify factors influencing the accuracy of estimated fetal weight in small for gestational age (SGA) fetuses. Methods: This retrospective cohort study included 268 women in the third trimester with singleton pregnancies and estimated fetal weight below the 10th percentile. Data were obtained from electronic medical records, and the Hadlock formula was used to estimate fetal weight through ultrasound measurements. Patients with fetal growth restriction due to placental insufficiency, preeclampsia, multiple pregnancies, or fetal anomalies were excluded from the study. The study groups were categorized based on differences between their estimated and actual birth weights. Results: The analysis showed that 24.3% of the cases had a difference of >10% between estimated and actual birth weights. The mode of delivery was significantly associated with weight difference, with a lower cesarean section rate in the group with a difference >10%. There were no significant differences in clinical and sonographic characteristics between the study groups. Perinatal outcomes did not exhibit significant differences in gestational age at delivery, delivery mode, sex, or meconium-stained amniotic fluid. However, there was a significant difference in birth weight, with higher birth weights observed in the group with a difference >10%. Logistic regression analysis did not reveal any statistically significant associations between the examined factors and weight differences >10%. Conclusion: This study highlights the challenges of accurately estimating fetal weight in SGA fetuses. Further research is needed to identify additional factors and develop more reliable methods for estimating fetal weight in these cases, aiming to improve prenatal management and reduce the risk of adverse outcomes.