背景:当代产科实践的主要目标是在整个怀孕期间优化胎儿的生长和发育。迄今为止,产前护理期间的胎儿生长通过进行二维胎儿生物测量的超声检查来评估,以计算估计的胎儿体重.我们小组先前使用来自具有多个超声图的大型队列的超声图像数据建立了二维胎儿生长标准。该调查的另一个目标涉及从同一队列中收集胎儿体积。
目的:胎儿3D研究旨在通过三维超声检查建立胎儿软组织和器官体积测量的标准,并将生长轨迹与常规二维测量进行比较。
方法:NICHD胎儿3D研究包括前瞻性收集的研究质量图像,种族和种族多样化,美国12个地点的低风险孕妇队列,每个胎儿最多扫描五次(N=1,730个胎儿)。从二维图像和从三维多平面视图提取的胎儿肢体软组织参数测量腹部皮下组织厚度。小脑,肺,使用虚拟器官计算机辅助分析(VOCAL)测量肝脏和肾脏体积。手臂和大腿总体积分数,测量了部分瘦肢体体积,通过从总量中减去瘦肉来计算肢体脂肪体积分数。对于每一项措施,加权曲线(第5条,50岁,第95百分位数)来自15-41周,使用线性混合模型进行三次样条重复测量。
结果:腹部皮下厚度,手臂,大腿呈线性增加,在27-29周左右轻微加速。手臂的分数体积,大腿,瘦肢体体积沿着二次曲率增加,加速约29-30周。相比之下,二维肱骨和股骨长度的生长模式表现出对数形状,在妊娠中期增长最快。中臂面积曲线的形状与臂体积分数相似,随着30周左右的加速,而瘦臂面积的曲线更平缓。腹部面积曲线与中臂面积曲线相似,加速度约为29周。大腿中部和瘦面积曲线与手臂区域不同,在39周时表现出减速。随着一些减速,中臂和大腿圆周的生长曲线更加线性。小脑二维直径线性增加,而小脑三维体积生长逐渐加速,直到32周,然后减速。肺,肾,和肝脏体积都显示出逐渐的早期增长,然后在25周开始的肺部线性加速,26-27周的肾脏,肝脏29周。
结论:三维瘦肉和脂肪测量的生长模式和最大生长时间,肢体和器官体积不同于传统的二维生长方法所揭示的模式,表明这些参数反映了胎儿生长的独特方面。这些三维测量的生长可能会被遗传改变,营养,代谢或环境影响和妊娠并发症,使用相应的二维度量无法识别的方式。进一步调查这些三维标准与胎儿生长异常的关系,不良围产期结局,出生后的健康状况是必要的。
BACKGROUND: A major goal of contemporary obstetrical practice is to optimize fetal growth and development throughout pregnancy. To date, fetal growth during prenatal care is assessed by performing ultrasonographic measurement of two-dimensional fetal biometry to calculate an estimated fetal weight. Our group previously established two-dimensional fetal growth standards using sonographic data from a large cohort with multiple sonograms. A separate objective of that investigation involved the collection of fetal volumes from the same cohort.
OBJECTIVE: The Fetal 3D Study was designed to establish standards for fetal soft tissue and organ volume measurements by three-dimensional ultrasonography and compare growth trajectories with conventional two-dimensional measures where applicable.
METHODS: The NICHD Fetal 3D Study included research-quality images of singletons collected in a prospective, racially and ethnically diverse, low-risk cohort of pregnant individuals at 12 U.S. sites, with up to five scans per fetus (N=1,730 fetuses). Abdominal subcutaneous tissue thickness was measured from two-dimensional images and fetal limb soft tissue parameters extracted from three-dimensional multiplanar views. Cerebellar, lung, liver and kidney volumes were measured using virtual organ computer aided analysis (VOCAL). Fractional arm and thigh total volumes, and fractional lean limb volumes were measured, with fractional limb fat volume calculated by subtracting lean from total. For each measure, weighted curves (5th, 50th, 95th percentiles) were derived from 15-41 weeks\' using linear mixed models for repeated measures with cubic splines.
RESULTS: Subcutaneous thickness of the abdomen, arm, and thigh increased linearly, with slight acceleration around 27-29 weeks. Fractional volumes of the arm, thigh, and lean limb volumes increased along a quadratic curvature, with acceleration around 29-30 weeks. In contrast, growth patterns for two-dimensional humerus and femur lengths demonstrated a logarithmic shape, with fastest growth in the 2nd trimester. The mid-arm area curve was similar in shape to fractional arm volume, with an acceleration around 30 weeks, whereas the curve for the lean arm area was more gradual. The abdominal area curve was similar to the mid-arm area curve with an acceleration around 29 weeks. The mid-thigh and lean area curves differed from the arm areas by exhibiting a deceleration at 39 weeks. The growth curves for the mid arm and thigh circumferences were more linear with some decelerations. Cerebellar two-dimensional diameter increased linearly, whereas cerebellar three-dimensional volume growth gradually accelerated until 32 weeks and then decelerated. Lung, kidney, and liver volumes all demonstrated gradual early growth followed by a linear acceleration beginning at 25 weeks for lungs, 26-27 weeks for kidneys, and 29 weeks for liver.
CONCLUSIONS: Growth patterns and timing of maximal growth for three-dimensional lean and fat measures, limb and organ volumes differed from patterns revealed by traditional two-dimensional growth measures, suggesting these parameters reflect unique facets of fetal growth. Growth in these three-dimensional measures may be altered by genetic, nutritional, metabolic or environmental influences and pregnancy complications, in ways not identifiable using corresponding two-dimensional measures. Further investigation into the relationships of these three-dimensional standards to abnormal fetal growth, adverse perinatal outcomes, and health status in postnatal life is warranted.