Regev-Sadeh Shira, Assaf Wisam, Zehavi Adi, Cohen Nadav, Lavie Ofer, Zilberlicht Ariel
Tel Aviv University Faculty of Medicine, Tel Aviv, Israel.
Department of Obstetrics and Gynecology, Lady Davis Carmel Medical Center, Haifa, Israel.
Int J Gynaecol Obstet. 2025 Feb;168(2):774-782. doi: 10.1002/ijgo.15911. Epub 2024 Sep 13.
To evaluate the optimal timing for fetal weight estimation during the third trimester.
This retrospective cohort study involved fetal weight estimations from both early (28-36 weeks) and late (37 weeks and beyond) third trimester. These estimations were converted to predicted birth weights using the gestation-adjusted projection formula. Birth weight predictions were compared with actual birth weights, to identify the most effective timing for weight prediction.
The study included 3549 cases, revealing mean percentage errors (MPE) of -3.69% for early sonographic assessments, -2.5% for late sonographic assessments, and -1.9% for late clinical assessments. A significant difference was found between early and late sonographic estimations (P < 0.001), whereas late sonographic and clinical assessments did not differ significantly (P = 0.771). Weight predictions for fetuses below the 10th and above the 90th centiles were less accurate than for those within the 10th-90th centiles (P < 0.001). In women with obesity, late clinical estimations were less precise (MPE of -5.85) compared with non-obese women (MPE of -1.66, P < 0.001). For women with diabetes, early sonographic estimations were more accurate (MPE of -1.31) compared with non-diabetic patients (MPE of -3.94, P < 0.001) though this difference did not persist later in pregnancy.
Sonographic and clinical weight predictions in the late third trimester were more accurate than earlier third-trimester sonographic assessments, hence continuous follow up and assessments closer to term are important. In women with diabetes, no adjustments in weight prediction methods are necessary. Accurately predicting birth weights for abnormally small or large fetuses remains challenging, indicating the need for improved screening and diagnostic strategies.
评估孕晚期胎儿体重估计的最佳时机。
这项回顾性队列研究涉及孕晚期早期（28 - 36周）和晚期（37周及以后）的胎儿体重估计。这些估计值使用孕周校正投影公式转换为预测出生体重。将出生体重预测值与实际出生体重进行比较，以确定体重预测的最有效时机。
该研究纳入3549例病例，早期超声评估的平均百分比误差（MPE）为 -3.69%，晚期超声评估为 -2.5%，晚期临床评估为 -1.9%。早期和晚期超声估计之间存在显著差异（P < 0.001），而晚期超声和临床评估无显著差异（P = 0.771）。低于第10百分位数和高于第90百分位数胎儿的体重预测不如第10 - 90百分位数之间的胎儿准确（P < 0.001）。肥胖女性的晚期临床估计不如非肥胖女性精确（MPE为 -5.85）（非肥胖女性MPE为 -1.66，P < 0.001）。对于糖尿病女性，早期超声估计比非糖尿病患者更准确（MPE为 -1.31）（非糖尿病患者MPE为 -3.94，P < 0.001），不过这种差异在妊娠后期未持续存在。
孕晚期的超声和临床体重预测比孕晚期早期的超声评估更准确，因此持续随访和接近足月时的评估很重要。对于糖尿病女性，无需调整体重预测方法。准确预测异常小或大胎儿的出生体重仍然具有挑战性，这表明需要改进筛查和诊断策略。
