Fetal transabdominal biometry at 11-14 weeks of gestation.

OBJECTIVE: To establish comprehensive transabdominal ultrasonographic reference ranges for viable normal singleton human fetuses at 11-14 weeks' gestation. METHODS: Single transabdominal ultrasound measurements were taken once per pregnancy at a gestational age of between 11+0 and 14+0 weeks (crown-rump length, 45-84 mm), in viable singleton fetuses with nuchal translucency < or = 3 mm and without detectable structural anomalies, using four standard planes: (i) biparietal diameter (BPD) and fronto-occipital diameter (FOD) resulting in head circumference (HC), anterior horn (Va), posterior horn (Vp), and hemisphere (HEM); (ii) transcerebellar diameter (TCD) and cisterna magna (CM); (iii) abdominal anteroposterior (AAP) and abdominal transverse diameter (ATD) resulting in abdominal circumference (AC); and (iv) femur length (FL). The respective ratios Va/HEM, Vp/HEM, HC/AC, BPD/FL, BPD/FOD, FL/CRL, FL/BPD and FL/AC and the estimated weight were derived. Reference ranges were constructed and the mean and 5th and 95th centiles were plotted against gestation. RESULTS: There was a general increase in biometric parameters with gestation. The ratios for the ventricles vs. hemisphere and BPD/FL ratio decreased while the BPD/FOD and HC/AC ratios remained constant. Analysis of the reference range for BPD/FL was performed in both 167 and 664 fetuses and the results showed almost the identical type of equation, indicating a high degree of accuracy for the growth charts. CONCLUSIONS: We have established comprehensive reference ranges for first-trimester fetal biometry by transabdominal sonography. These charts may have a role in the diagnosis of early onset symmetrical or asymmetrical growth restriction and in the interpretation of measurements in chromosomally abnormal fetuses, and they may help in the detection of skeletal dysplasias or acrania/anencephaly.     

Nomograms of the axial fetal cerebellar hemisphere circumference and area throughout gestation.

OBJECTIVE: The widely applied transcerebellar diameter (TCD) obtained at axial cranial imaging, measures the distance between the lateral aspects of the cerebellum and incorporates the width of the cerebellar vermis. Our objective was to create reference ranges of axial fetal cerebellar hemisphere circumference (CHC) and area (CHA), independent of the cerebellar vermis, throughout gestation. METHODS: This cross-sectional study involved pregnant patients between 14 and 41 weeks of gestation. Inclusion criteria consisted of well-established dates (confirmed by early ultrasound), non-anomalous singleton fetuses and intact amniotic membranes. Sonographic measurements included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), humerus length (HL), TCD, and estimated fetal weight (EFW). Values of axial fetal CHC and CHA were each calculated as the mean of three separate measurements. The 5th, 50th and 95th centiles were estimated at each week of gestational age (GA) by least-squares regression for the mean and standard deviation (SD) of the CHC and CHA as functions of GA. r2 and associated P-values for the relationships of CHC and CHA with other sonographic biometric measurements were calculated. RESULTS: The study included 651 consecutive patients. All attempts at obtaining axial fetal CHC and CHA were successful. Mean maternal age was 27.3+/-6.7 years, median gravidity was 1 (range 1-16), and median parity was 1 (range 0-6). Mean CHC (cm) throughout gestation was modeled as -2.091+0.2563xGA (weeks) (SD=-0.075+0.0164xGA), and mean CHA (cm2) was modeled as 0.245-0.0765xGA+0.00506xGA2 (SD=1.167-0.1565xGA+0.006785xGA(2)-0.00008028xGA3). Fetal axial CHC and CHA correlated significantly and strongly with BPD, HC, AC, HL, FL, TCD and EFW (all R2 values were >or=0.95, and all P-values were <0.001). CONCLUSION: Nomograms of axial fetal cerebellar hemisphere circumference and area throughout gestation, independent of the cerebellar vermis, have been provided.     

Are the international ultrasound reference standards appropriate for Iranian fetuses

SUMMARY: The article describes the development of ultrasound tables for biparietal diameter (BPD), femur length (FL), abdominal circumference (AC), and head circumference (HC) for fetuses in Iran. It was attempted to determine if racial differences exist between Iranian and Australian fetuses in ultrasound measurements of BPD, HC, AC, and FL. The sample for this study consisted of 70 Iranian and 93 Australian pregnant women. The Iranian women received prenatal care and delivered at Fatemieh Hospital in Shahrood, Iran during October 1998 through February 1999. All these women had an ultrasound scan for anomalies in the second trimester. We selected only those pregnancies in which the estimated date of delivery by last menstrual period was within +/-14 days of the estimated date of delivery determined by the initial ultrasound examination. The data from Australian fetuses were obtained from the ultrasound section at the Wollongong Hospital in Australia. Birth weight differences were observed, with Australian infants being heavier than Iranian infants. The results also showed Australian fetuses have longer FL and larger HC, AC, and BPD than Iranian fetuses in the third trimester. Overall, this study shows that race-specific standards for estimating gestation age (GA) may be an important consideration in improving the accuracy of ultrasound estimation of GA. Because the evaluation of retardation growth retardation is so dependent on GA, assessment using standards specific to the Iranian race may more accurately classify infants and improve the prenatal diagnosis of fetal growth disturbances. Using European or Australian standards may cause overestimation of the rate of growth-retarded fetuses in Iranian pregnancies.     

Significance of ultrasound measurements of the head of the breech fetus

Ultrasound measurements of head shape and size in 451 fetuses presenting as a breech were compared to those obtained in 1,880 fetuses presenting as a cephalic between 15 and 40 weeks' gestation. No statistically significant differences were found for the biparietal diameter (BPD), head circumference (HC), or cephalic index (CI) measurements between the two groups in uncomplicated pregnancies. The mean values for the CI were found to be lower for breech presenting fetuses in complicated pregnancies, indicating a trend for these fetuses to have a more dolichocephalic head shape.     

胎儿超声心动图检查定量11~17周正常胎儿主动脉和肺动脉内径Z-评分的初步研究

目的探讨早孕期（11^＋0周~13^＋6周）和中孕早期（14^＋0周~17^＋6周）胎儿主动脉内径（AO）与肺动脉内径（PA）与胎儿生物学生长参数的相关性,初步建立早孕期和中孕早期胎儿AO与PA的正常参考值范围及Z-评分方程,并评价方程的有效性。 方法随机选取孕周（GA）为（11^＋0周~17^＋6周）正常单胎胎儿270例,将成功显示左、右心室流出道切面的245例胎儿纳入研究,获得胎儿顶臀径（CRL）、双顶径（BPD）、股骨长径（FL）、孕周（GA）等生物学生长参数。在胎儿左、右心室流出道切面测量收缩末期AO及PA,以GA、BPD和FL作为独立自变量,AO及PA作为因变量,建立AO、PA的正常参考值范围,并对每个参数的绝对残差（SD）进行加权回归,建立Z-评分方程。 结果采用简单的线性回归模型,可以很好地描述AO和PA与非心脏生物特征参数（BPD、FL、GA）的关系。AO、PA与GA、BPD、FL均呈显著线性相关（GA与AO：r=0.9276,GA与PA：r=0.9271,BPD与AO：r=0.9551,BPD与PA：r=0.9558,FL与AO：r=0.9462,FL与PA：r=0.9483,均<0.001）,其中与BPD的相关性最强。 结论正常早孕期及中孕早期胎儿的AO、PA随着孕周的增加而增长,本研究初步建立了正常胎儿早孕期及中孕早期AO、PA的参考范围及其Z-评分方程。为早孕期及中孕早期评估胎儿大血管生长提供精确的参考标准,在早期筛查或诊断胎儿先天性心脏畸形方面具有潜在的应用价值。     

Patterns of Fetal Growth in a Rural Indian Cohort and Comparison With a Western European Population

Objective. The purpose of this study was to describe fetal size on sonography in a rural Indian population and compare it with those in European and urban Indian populations. Methods . Participants were from the Pune Maternal Nutrition Study of India. Fetal growth curves were constructed from serial ultrasound scans at approximately 18, 30, and 36 weeks' gestation in 653 singleton pregnancies. Measurements included femur length (FL), abdominal circumference (AC), biparietal diameter (BPD), and occipitofrontal diameter, from which head circumference (HC) was estimated. Measurements were compared with data from a large population‐based study in France and a study of urban mothers in Vellore, south India. Results. Fetal AC and BPD were smaller than the French reference at 18 weeks' gestation (?1.38 and ?1.30 SD, respectively), whereas FL and HC were more comparable (?0.77 and ?0.59 SD). The deficit remained similar at 36 weeks for AC (?0.97 SD), FL (?0.43 SD), and HC (?0.52 SD) and increased for BPD (?2.3 SD). Sonography at 18 weeks underestimated gestational age compared with the last menstrual period date by a median of ?1.4 (interquartile range, ?4.6, 1.8) days. The Pune fetuses were smaller, even at the first scan, than the urban Vellore sample. Conclusions. Fetal size was smaller in a rural Indian population than in European and urban Indian populations, even in mid pregnancy. The deficit varied for different fetal measurements; it was greatest for AC and BPD and least for FL and HC.     

Nomogram of maxillary bone length in normal pregnancies.

OBJECTIVE: The aim of this study was to define normal ultrasonographic growth of the fetal maxillary bone throughout pregnancy as a basis for further studies and as normative data for assessing deviations in growth. METHODS: A prospective cross-sectional study was performed. Consecutive routine biometric measurements and fetal organ scans were obtained from patients undergoing elective fetal anatomic surveys. Special attention was paid to the profile view of the fetal face, and the maxillary bone was identified and measured. RESULTS: Three hundred twenty-seven fetuses between 13 and 40 weeks' gestation were scanned. The maxillary bone is seen as a rodlike structure; it is a part of the facial skeleton that allows the opening and closing of the pharynx. A linear growth function was observed across gestational age (GA), and first-degree correlation was found to exist between GA and the maxillary bone (r = .645; P < .0001; y = 7.78 + 0.18 x GA). Significant correlation was also found between the maxillary bone and biparietal diameter (BPD) (r = 0.652; P > .0001; y = 8.36 + 0.66 x BPD), head circumference (HC) (r = .645; P < .0001; y = 8.39 + 0.18 x HC), femoral bone length (FBL) (r = .640; P < .0001; y = 9.28 + 0.7 x FBL), and abdominal circumference (AC) (r = .640; P < .0001; y = 8.91 + 0.17 x AC). CONCLUSIONS: Normative data for ultrasonographic measurements of the fetal maxillary bone throughout pregnancy are provided. These data potentially allow the prenatal diagnosis of abnormal maxillary bone length.     

巨大胎儿体质量估测新公式的建立和验证

目的 创建用于巨大胎儿体质量估测新公式,并将新公式和现有的25个公式进行比较.方法 对1153例胎儿(其中239例巨大胎儿)在出生前1周以内行产科超声检查,测量胎儿双顶径(BPD)、头围(HC)、腹围(HC)、和股骨长(FL),出生后记录胎儿体质量.采用逐步回归法设计新公式,1034例(914例非巨大胎儿+120例巨大胎儿)数据用于建立新的全范围体质量预测公式,239例巨大胎儿中120例数据为训练集,被用于建立疑似巨大胎儿胎重估测公式,其余119例巨大胎儿(测试集)用于公式验证,并与国内外常用25个公式相比较.结果 全范围体质量估测公式为:lgBW=0.180(HC)+0.00628 (AC)-0.00318(HC)2+0.00173 (AC) (FL)+0.0000430 (BPD) (HC)2.疑似巨大胎儿胎重估测公式为:lgBW=0.730(BPD) -0.0375 (BPD)2+0.000264 (AC) (FL).新估测公式对119例测试集的平均误差为(- 87.89±230.95)g,平均绝对百分误差为(4.4±3.9)％,25个公式中误差最小公式的平均估测误差为(115.61±345.09)g,平均绝对百分误差为(6.8±5.4)％,新公式与公认的其他常用公式相比,平均绝对误差、平均绝对百分误差均为最低.结论 新公式评估胎儿体质量的准确性较高.新公式适宜于评估中国胎儿体质量,尤其适合评估巨大胎儿体质量.     

Sex-specific antenatal reference growth charts for uncomplicated singleton pregnancies at 15-40 weeks of gestation.

OBJECTIVE: Female fetuses, on average, weigh less than male fetuses at all gestational ages. The purpose of this study was to compare female and male fetuses in terms of intrauterine ultrasound growth measurements and to develop gestational-age-related charts based on a computerized perinatal database. METHODS: This was a retrospective study of unselected women in the second and third trimesters of pregnancy, who had a normal scan at 10-14 weeks. Data analysis was performed using measurements obtained from a mixed-race population of 4234 women, who underwent 5198 ultrasound examinations. The scans were performed by four trained sonographers, according to a standardized protocol. Routine measurements included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). The main end-points were sex- and race-specific differences in fetal biometry, which were also used to estimate fetal weight. RESULTS: The base-line demographic characteristics and risk factors were comparable in female and male fetuses. Significant differences in fetal BPD, HC, AC and estimated fetal weight, but not FL, were seen between male and female fetuses. Centile charts for each of these variables were constructed for both male and female fetuses. CONCLUSIONS: This study suggests that small but consistent sex-related differences in prenatal BPD, HC and AC measurements are established by as early as 15 weeks of gestation. The use of sex-specific nomograms may improve the prenatal assessment of fetal growth as well as the diagnosis of structural abnormalities.     

The assessment of normal fetal brain volume by 3-D ultrasound

The assessment of the fetal brain volume (BV) is very important in the evaluation of fetal growth. The purpose of this study is to use the three-dimensional (3-D) ultrasound (US) in constructing reference centiles of the fetal BV during normal gestation for clinical application. This study was undertaken by a prospective and cross-sectional design. In total, 203 singleton fetuses ranged between 20 and 40 weeks of gestation and fit the criteria of normal pregnancies were enrolled in this study. Our results showed that fetal BV is highly correlated with the gestational age (GA). Furthermore, using GA as the independent variable and the fetal BV as the dependent variable, the best-fit regression equation was BV (mL)=-171.48036+4.8079xGA+0.29521xGA2 (r=0.99, n=203, p<0.0001), with SD of BV (mL)=1.2533x(9.9474+0.07133xGA). In addition, the common growth parameters of the fetal biometry, such as biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HC), abdominal circumference (AC), femur length (FL) and estimated fetal weight (EFW), were all highly correlated with the fetal BV (all p<0.0001). In conclusion, our data on the fetal BV assessed by 3-D US may serve as a useful reference in evaluating fetal growth.     

Revisiting first-trimester fetal biometry.

INTRODUCTION: Although advances in ultrasound have facilitated the diagnosis of fetal abnormalities in the first trimester, fetal biometry at this stage of pregnancy remains underused in prenatal diagnosis. We hypothesized that charts which directly correlate measurements to crown-rump length (CRL) could be more accurate than those based on gestational age (GA) derived from CRL measurement. The aim of this study was to construct CRL-based biometric charts. METHODS: Measurements of biparietal diameter (BPD), head circumference (HC) and abdominal circumference (AC) were prospectively collected from 939 normal singleton fetuses. Charts and predictive equations were constructed from data obtained from pregnancies in which the CRL was between 45 and 84 mm and for which the outcome was normal. RESULTS: Measurements of BPD, HC and AC from 880 fetuses who met the criteria were correlated with CRL and used to construct charts and predictive equations. The standard error of estimates using CRL was significantly lower than that using GA in all cases. DISCUSSION: First-trimester growth charts and predictive equations based on CRL instead of GA are more accurate. They might have a role in quality control of first-trimester ultrasound examination and may help in the diagnosis of fetal conditions that involve early growth abnormalities.     

The assessment of normal fetal liver volume by three-dimensional ultrasound

Liver volume (LIVV) is very important in determining the status of fetal growth. However, to measure human fetal LIVV in utero precisely and noninvasively is not an easy task. With the recent advancement of three-dimensional (3-D) ultrasound (US), the limitation in assessing fetal LIVV by 2-D US can be overcome. The purpose of this study was to establish a normal reference chart of fetal LIVV for clinical use. A prospective and cross-sectional study using 3-D US was undertaken to assess the fetal LIVV in normal pregnancy. In total, 226 singleton fetuses ranging between 20 and 40 weeks of gestation and fitting the criteria of normal pregnancies were enrolled in this study. Our results showed that fetal LIVV is highly correlated with the gestational age (GA). Furthermore, using GA as the independent variable and fetal LIVV as the dependent variable, the best-fit regression equation was LIVV (mL) = -398.26 + 46.199 xGA - 1.7567 x GA(2) + 0.0236 x GA(3) (r = 0.97, n = 226, p < 0.0001), with SD of LIVV (mL) = 1.2533 x (0.77956 + 0.17267 x GA). These common indexes of fetal biometry, such as biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HCi), abdominal circumference (ACi), femur length (FL), and estimated fetal weight (EFW), were all highly correlated with fetal LIVV (all p < 0.0001). In conclusion, our data of fetal LIVV assessed by 3-D US can serve as a useful reference in evaluating fetal growth status during normal gestation.     

Fractional spine length: a new parameter for assessing fetal growth

Sonographic measurement of a segment of the lower thoracic and lumbar fetal spine was performed on 218 normal fetuses of between 15 and 42 weeks' gestational age (GA) to establish a new parameter for assessing fetal growth. The increase of the fractional spine length (FSL) was represented by the equation: FSL = -37.62 + 4.36 (GA) - 0.04 (GA)2, with R2 = 0.92. The FSL also correlates strongly with fetal femur length (FL): FSL = 5.36 + 0.82 (FL), with R2 = 0.93. The ratio FSL/abdominal circumference (AC) X 100 was relatively constant at 20.4 +/- 3.1 (mean +/- 2 standard deviations) from 19 to 42 weeks in contrast to the ratio FL/AC X 100, which was constant at 22.3 +/- 2.4 (mean +/- 2 SD) only after 23 weeks. Nine of 10 small-for-gestational age fetuses examined during the study had a FSL within the normal range, as well as two fetuses who were thanatophoric dwarfs. The FSL provides a new ultrasonic longitudinal measurement of the fetus which may be used in addition to the femur length in fetal growth assessment.     

构建正常胎儿心胸比Z评分模型

目的 构建正常胎儿心胸比（CTR）Z评分模型,包括横径比（CTR1）、周长比（CTR2）和面积比（CTR3）。方法 对954胎孕11~40⁺⁶周正常胎儿行产前超声检查,于标准切面测量CTR作为因变量,以胎体大小参数,包括孕周（GA）、双顶径（BPD）及股骨长度（FL）为自变量,行回归分析,获得CTR均数回归方程;并分析CTR残差,以确定CTR标准差的最佳回归方程;根据公式计算CTR Z评分。结果 正常胎儿CTR与GA、BPD及FL均呈正相关（r=0.74~0.86,P均<0.05）;胎儿CTR参数与胎体大小参数的最佳拟合方程均为直线回归方程。成功构建了基于胎体大小参数CTR均数的拟合回归方程;CTR残差分析结果提示CTR标准差不随胎体大小变化而改变,均为恒定值标准差;根据方程可计算正常胎儿CTR Z评分。结论 基于GA、BPD及FL建立的正常胎儿CTR Z评分模型可为产前评估胎儿发育提供参考。     

多参数比值超声监测胎儿宫内生长发育速度

目的 探讨不同类型胎儿宫内生长发育的特点,方法 分析1998年6月至1999年10月期间本院正常分娩的新生儿695例,其中正常体重新生儿500例,巨大儿147例,IUGR新生儿48例,分析妊娠期间双顶径／腹径腹径／股骨长比例的变化趋势,结果 胎儿双顶经／腹径比例巨大儿最小,IUGR胎儿最大,整个孕期呈下降趋势,腹径／股骨长比例巨大儿最大,IUGR胎儿最小,结论 胎儿宫内生长发育趋势表明,胎儿体重的增加,主要是胎儿腹径的增加占优势。     

The fetal cerebellar vermis: anatomy and biometric assessment using volume contrast imaging in the C-plane (VCI-C).

OBJECTIVES: To describe the normal appearance and study the biometry of the fetal cerebellar vermis by three-dimensional (3D) volume contrast imaging in the coronal (C-) plane (VCI-C). METHODS: A total of 203 normally developed fetuses were examined prospectively at 18-33 weeks' gestation. At the level of the view used to measure the transverse cerebellar diameter (TCD), a VCI-C plane was displayed to examine, using a transabdominal probe, the fetal mid-saggital vermis. The volumes acquired were stored for later review and measurement of the anteroposterior (AP) diameter, craniocaudal (CC) diameter and surface area of the cerebellar vermis. Each dataset was evaluated by two independent observers. Measurements as a function of gestational age (GA), biparietal diameter (BPD), head circumference (HC) and TCD were expressed by regression equations. Interobserver variability was evaluated. Nomograms were produced. In order to validate the use of VCI in fetal biometry, datasets from 57 patients were selected arbitrarily for comparison of their VCI-C measurements with those from mid-sagittal sections of a stored 3D multiplanar examination. Intraclass correlation was used to evaluate the agreement between these measurements. RESULTS: The mean maternal age was 32 years. We were able to measure mid-sagittal CC diameter, mid-sagittal AP diameter and cerebellar vermis surface area in all fetuses. Interobserver variability analysis showed no significant differences between the two observers (P > 0.05). Measurements of the cerebellar vermis (AP diameter, CC diameter and surface area) correlated linearly with GA, BPD, HC and TCD (r > or = 0.82, P < 0.0001). CC and AP diameters estimated from the mid-sagittal section of the multiplanar measurements were significantly correlated with VCI-C measurements (r = 0.96, P < 0.00001 and r = 0.95, P < 0.00001, respectively). CONCLUSIONS: VCI-C is a valuable tool, allowing intrauterine assessment of the normal appearance of the fetal cerebellar vermis. The nomograms developed in this study should enable accurate evaluation of the cerebellar vermis.     

Sex-specific fetal weight prediction by ultrasound.

OBJECTIVE: To improve sonographic birth-weight prediction by developing fetal gender-specific formulae. METHODS: This was a retrospective cross-sectional study. Two gender-specific formulae were produced from the data of 527 patients and the data of a further 349 patients were used to evaluate the formulae. Inclusion criteria were a singleton live fetus, gestational age above 25 weeks, birth weight between 1000 g and 4500 g and fetal biometry within 8 days of delivery. Data retrieval was specifically for the purpose of this study. RESULTS: To yield the best-fit weight formula for each fetal gender we employed step-wise regression analysis based on fractional polynomials with the biometric parameters biparietal diameter (BPD), head circumference (HC), transverse abdominal diameter (TAD), abdominal circumference (AC) and femur length (FL): estimated fetal weight for girls (g) = - 4035.275 + 1.143 x BPD3 + 1159.878 x AC1/2 + 10.079 x FL3 - 81.277 x FL2 [in cm]; estimated fetal weight for boys (g) = 43576.579 + 1913.853 x log10BPD + 0.01323 x HC3 + 55.532 x AC2 - 13602.664 x AC1/2 - 0.721 x AC3 + 2.31 x FL3 [in cm]. These formulae showed superior results compared with those of conventional weight formulae. CONCLUSION: Gender-related fetal weight calculation allows optimized prediction of fetal weight at birth.     

Volumetric assessment of normal fetal lungs using three-dimensional ultrasound

We attempted to construct normal reference centiles of fetal lung volume (LV) for clinical application by using three-dimensional (3-D) ultrasound (US) during normal gestation. A prospective study was performed on 195 healthy fetuses with gestational age (GA) ranging from 20 to 40 weeks for the assessment of fetal LV using a 3-D US volume scanner with a mixture of cross-sectional and serial measurements. Polynomial regression analysis was calculated to find the best-fit model between GA, right lung volume (RLV), left lung volume (LLV) and total lung volume (TLV). In addition, common fetal growth parameters, such as biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HCi), abdominal circumference (ACi), femur length (FL) and estimated fetal weight (EFW) were also measured to demonstrate the correlations between RLV, LLV, TLV and these parameters. Our results showed that RLV, LLV and TLV were highly correlated with GA. Using GA as the independent variable and RLV, LLV and TLV as the dependent variable, the best-fit regression equations were: RLV (mL) = 0.067 GA(2) - 1.2464 GA + 2.7825 (r = 0.95, n = 173, p < 0.0001), LLV (mL) = 0.0573 GA(2) - 1.599 GA + 12.454 (r = 0.95, n = 159, p < 0.0001) and TLV (mL) = 0.1263 GA(2) - 2.982 GA + 17.448 (r = 0.96, n = 152, p < 0.0001). For clinical use, a chart of normal growth centiles of fetal LV in utero was then calculated based on this equation. Furthermore, RLV, LLV and TLV were also highly correlated with the common fetal growth parameters during normal gestation (all p < 0.0001). In conclusion, the 3-D US nomograms of the fetal lung volume established in this study can be utilized as useful references in prenatal detection of fetal pulmonary pathologic status and relevant abnormalities.     

Development of Z-scores for fetal cardiac dimensions from echocardiography.

OBJECTIVES: Z-scores for cardiac dimensions are well established in postnatal life, but have yet to be developed for fetal cardiac dimensions. These would be of real advantage to the clinician in accurately quantifying size and growth of cardiac dimensions and to the researcher by allowing mathematical comparison of growth in differing subgroups of a disease. The purpose of this observational study, conducted at tertiary fetal medicine and cardiology units, was to produce formulae and nomograms allowing computation of Z-scores for fetal cardiac dimensions from knowledge of femur length (FL), biparietal diameter (BPD) or gestational age (GA) using fetal echocardiography. METHODS: Seventeen fetal cardiac dimensions were measured in 130 pregnant women with singleton fetuses of gestational age 15-39 weeks. Regression equations were derived relating all dimensions to FL, BPD and GA. From the calculations, formulae were then developed allowing fetal cardiac Z-score computation. RESULTS: The relationships between cardiac dimensions and FL, BPD or GA were described following natural log transformation. From this analysis, FL (taken as an expression of fetal size) had the highest correlation to fetal cardiac dimensions. From the developed nomograms, Z-scores of specific fetal cardiac structures could be estimated from knowledge of the FL, BPD or GA and echocardiographically derived measurements. CONCLUSIONS: This study allowed computation of Z-scores in fetal life for 17 cardiac dimensions from FL, BPD or GA. Previous studies of normal data allowed qualitative assessment of where abnormal cardiac dimensions lay with regard to the normal range. Z-scores from this study allow quantitative analysis of where such dimensions lie relative to the mean. This permits exact assessment of growth of fetal cardiac structures in normal hearts and particularly in congenitally abnormal hearts where quantitative assessment of the growth of cardiac structures is important in analyzing and planning treatment strategies.     

Nomograms of the fetal neck circumference and area throughout gestation.

OBJECTIVE: The purpose of this study was to create reference range nomograms of the axial fetal neck circumference (FNC) and fetal neck area (FNA) throughout gestation. METHODS: This prospective cross-sectional study involved pregnant patients between 14 and 40 weeks' gestation. Inclusion criteria consisted of well-established dates (confirmed by early sonography) and nonanomalous singleton fetuses with intact fetal membranes. Sonographic measurements included biparietal diameter, head circumference, abdominal circumference, femur length, humerus length, transcerebellar diameter, and sonographically estimated fetal weight. Axial FNC and FNA values were calculated as means of 3 separate measurements. The 5th, 50th, and 95th percentiles were estimated at each week of gestational age (GA) by least squares regression for the mean and SD of the FNC and FNA as functions of GA. R(2) and associated P values for the relationships between the FNC, FNA, and other sonographic biometric measurements were calculated. RESULTS: The study included 720 consecutive patients. The mean maternal age +/- SD was 27.3 +/- 6.6 years; median gravidity, 3 (range, 1-13); and median parity, 1 (range, 0-10). The following equations were devised: mean FNC (centimeters) = -11.85 + 1.687 x GA (weeks) -0.043 x GA(2) + 0.0004951 x GA(3); SD(FNC) = 3.15 - 0.3823 x GA + 0.01733 x GA(2) - 0.0002179 x GA(3); mean FNA (square centimeters) = 37.29 - 7.0 x GA + 0.4717 x GA(2) - 0.01245 x GA(3) + 0.0001222 x GA(4); and SD(FNA) = 7.08 - 0.9413 x GA + 0.04135 x GA(2) - 0.0004829 x GA(3). Both the FNC and FNA correlated significantly and strongly with biparietal diameter, head circumference, abdominal circumference, humerus length, femur length, transcerebellar diameter, and sonographically estimated fetal weight. CONCLUSIONS: Current nomograms of the axial FNC and FNA throughout gestation have been provided.