Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh Medical Center Magee-Womens Hospital, Pittsburgh, PA.
Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh Medical Center Magee-Womens Hospital, Pittsburgh, PA.
Am J Obstet Gynecol MFM. 2022 May;4(3):100615. doi: 10.1016/j.ajogmf.2022.100615. Epub 2022 Mar 11.
Antenatally, we rely on ultrasound estimated fetal weight as a proxy for birthweight to inform discussions regarding perinatal morbidity and mortality. Maternal obesity may negatively impact the quality of ultrasound imaging, and thus, understanding the associations between obesity and estimated fetal weight in the preterm period is important.
Given the rising obesity rates and association with preterm birth, we sought to determine the accuracy of ultrasound-derived estimated fetal weight in predicting birthweight in preterm infants by prepregnancy body mass index and to evaluate the accuracy of estimated fetal weight in predicting birthweight between small-for-gestational-age and appropriate-for-gestational-age infants.
We included all women who delivered a live-born singleton infant between 23 0/7 and 31 6/7 weeks of gestation and had an ultrasound estimated fetal weight within 7 days before delivery. We calculated the mean percentage difference between estimated fetal weight and birthweight and the absolute percent difference. Excess error was defined as an absolute percentage difference of >20%. We used multivariable modified Poisson models to determine the association between prepregnancy body mass index and small for gestational age and excess ultrasound error.
Our cohort included 641 infants with a mean gestational age of 28.0±2.6 weeks and a mean birthweight of 1110±425 g. More than one-third of our cohort were obese (227 [35%]). The mean percentage difference between estimated fetal weight and birthweight was 7.7%±11.2% among all infants. Ultrasound overestimated birthweight in 77% of the cohort (n=492). Stratified by body mass index, the mean percentage differences between estimated fetal weight and birthweight were 6.7%±11.0% in women with normal weight and 9.5%±12.0% in women with obesity (P=.02). The mean percentage differences between estimated fetal weight and birthweight were 11.0%±11.0% in small-for-gestational-age infants (n=80) and 7.1%±11.0% in appropriate-for-gestational-age infants (P<.001). Small-for-gestational-age infant was associated with an increased risk of excess ultrasound error with an adjusted relative risk of 2.3 (95% confidence interval, 1.2-4.3).
Although ultrasound estimated fetal weight overestimated birthweight, particularly in small-for-gestational-age infants, most estimates were within 10% of actual birthweight. Obesity and small-for-gestational-age birth were both associated with an increased risk of excess ultrasound error (≥20%) in estimating birthweight.
在产前阶段，我们依赖超声估计的胎儿体重来预测围产期发病率和死亡率，以此作为出生体重的替代指标。肥胖可能会对超声成像质量产生负面影响，因此，了解早产期间肥胖与估计胎儿体重之间的关系非常重要。
鉴于肥胖率不断上升并与早产有关，我们旨在确定通过孕前体重指数来确定早产儿超声估计胎儿体重预测出生体重的准确性，并评估估计胎儿体重在预测小于胎龄儿和适于胎龄儿出生体重方面的准确性。
我们纳入了所有在妊娠 23 0/7 至 31 6/7 周之间分娩活产单胎婴儿且在分娩前 7 天内进行超声估计胎儿体重的女性。我们计算了估计胎儿体重与出生体重之间的平均百分比差异和绝对百分比差异。过度误差定义为绝对百分比差异>20%。我们使用多变量修正泊松模型来确定孕前体重指数与小于胎龄儿和超声误差过大之间的关联。
我们的队列包括 641 名平均孕龄为 28.0±2.6 周、平均出生体重为 1110±425g 的婴儿。我们队列中有超过三分之一的女性为肥胖（227[35%]）。所有婴儿中，估计胎儿体重与出生体重之间的平均百分比差异为 7.7%±11.2%。在队列中，超声高估了 77%（n=492）的出生体重。按体重指数分层，正常体重女性的估计胎儿体重与出生体重之间的平均百分比差异为 6.7%±11.0%，肥胖女性为 9.5%±12.0%（P=.02）。小于胎龄儿（n=80）的估计胎儿体重与出生体重之间的平均百分比差异为 11.0%±11.0%，适于胎龄儿的为 7.1%±11.0%（P<.001）。小于胎龄儿与超声误差过大的风险增加相关，调整后的相对风险为 2.3（95%置信区间，1.2-4.3）。
尽管超声估计的胎儿体重高估了出生体重，特别是在小于胎龄儿中，但大多数估计值都在实际出生体重的 10%以内。肥胖和小于胎龄儿出生都与估计出生体重的超声误差过大（≥20%）风险增加有关。
