Assessment of fetal gestational age in different trimesters from ultrasonographic measurements of various fetal biometric parameters

Introduction: Fetal biometry is a methodology devoted to measuring several parts of fetal anatomy and their growth. Aim: The present study was carried out to assess gestational age in the second and third trimesters with the help of ultrasonographic measurements of four fetal biometric parameters (i.e., biparietal diameter [BPD], head circumference [HC], abdominal circumference [AC], and femur length [FL]) in the local population (Jaipur Zone) of Rajasthan, and also to evaluate efficacy and significance of these four fetal biometric parameters in the prediction of gestational age by ultrasound. Materials and methods: Three hundred and thirty cases of normal pregnant females were studied (165 - second trimester [13–28 weeks] and 165 - third trimester [29–40 weeks]) with the known last menstrual period (LMP) and studied once during gestation. Results: Biparietal diameter and head circumference were found to be equally best predictors of gestational age and to determine the expected date of delivery (EDD) in the second trimester and BPD and FL in the third trimester. Abdominal circumference was the least accurate parameter in both trimesters. Variability in predicting gestational age (using all four parameters) was ±2 weeks in the second trimester and +2 to ?4 weeks in the third trimester. The accuracy decreased and variability increased as the pregnancy advanced from the second to third trimester. Mean measurements of fetal biometric parameters were found lower than Western monograms in each week of both trimesters. Conclusions: Variation in predicted gestational age by ultrasonography (USG) is attributed to the anthropometric difference between the two populations due to racial, genetic, nutritional, and socioeconomic factors. Therefore, population-specific measurements should be made to generate tables and regression equations for more precise reporting of gestational age and EDD by USG.     

Sonographic measurement of ear length among normal fetuses of pregnant Igbo women in port Harcourt,Nigeria

BackgroundFetal ear length measurement has been associated with some clinical values: sonographic marker for chromosomal aneuploidy and for biometric estimation of fetal gestational age.ObjectivesTo establish a baseline reference value for fetal ear length and to assess relationship between fetal ear length and gestational age.MethodsEar length measurements were obtained prospectively from fetuses in 551 normal singleton pregnancies of 15 to 41 weeks gestation. Normal cases were defined as normal sonographic findings during examination plus normal infant post-delivery. The relationship between gestational age (GA) in weeks and fetal ear length (FEL) in millimeters were analyzed by simple linear regression. Correlation of FEL measurements with GA, biparietal diameter (BPD), Head circumference (HC), Abdominal Circumference (AC), Femur Length (FL) and maternal age (MA) were also obtained.ResultsLinear relationships were found between FEL and GA (FEL=0.872GA-2.972). There was a high correlation between FEL and GA (r = 0.837; P = .001). Good linear relationship and strong positive correlation were demonstrated between FEL and BPD, AC, HC, and FL (p<0.05).ConclusionThe result of this study provides normal baseline reference value for FEL. The study also showed good linear relationship and good correlation between FEL and fetal biometric measurements.     

基于人工神经网络的足月胎儿体重预测方法

对胎儿体重的预测在产科临床上具有非常重要的意义,传统上采用回归分析方法预测胎儿体重,存在可靠性差等缺点。本研究采用反向传播(BP)人工神经网络方法预测胎儿体重,实验中采用双顶径、小脑横径、腹围、肝脏长度、股骨长度、股骨皮下脂肪厚度、孕龄等参数作为BP神经网络的输入参数,网络由输入层、隐含层和输出层三部分组成。对109例临床资料进行预测,结果为:训练组预测符合率达89.77%,平均绝对误差104.22g,平均相对误差3.24%;验证组预测符合率达76.19%,平均绝对误差190.84g,平均相对误差5.60%。表明人工神经网络预测胎儿体重方法十分有效,准确性高于回归方程。     

Longitudinal reference ranges for fetal ultrasound biometry in twin pregnancies

OBJECTIVE:

The purpose of this study was to establish longitudinal reference ranges for fetal ultrasound biometry measurements and growth parameters in twin pregnancies.

METHOD:

A total of 200 uncomplicated twin pregnancies before 21 weeks of gestation were recruited for this prospective, longitudinal study. Women who abandoned follow-up, pregnancies with unknown outcomes or pregnancies with complications were excluded. Ultrasound scans were performed every three weeks, and biparietal and occipitofrontal diameters, head and abdominal circumferences, and femur diaphysis length measurements were obtained for each fetus at each visit. Estimated fetal weight, biparietal/occipitofrontal diameter, head circumference/abdominal circumference, and femur diaphysis length/abdominal circumference ratios were also calculated. Multilevel regression analysis was performed on normalized data.

RESULTS:

A total of 807 ultrasound examinations were performed in 125 twin pregnancies between 14 and 38 weeks of gestation (6.5±1.4 scans/pregnancy). Regression analysis demonstrated significant correlations for all variables with gestational age, namely log of the biparietal diameter (r = 0.98), log of the occipitofrontal diameter (r = 0.98), log of the head circumference (r = 0.99), log of the abdominal circumference (r = 0.98), square root of the femur length (r = 0.99), log of the estimated fetal weight (r = 0.99), biparietal/occipitofrontal ratio (r = -0.11), head/abdomen circumference ratio (r = -0.56), and log of the femur length/abdominal circumference ratio (r = 0.61). Values corresponding to the 10^th, 50^th, and 90^th percentiles for estimated fetal weight at 28, 32, and 36 weeks, respectively, were as follows: 937, 1,096, 1,284 g; 1,462, 1,720, 2,025 g; and 2,020, 2,399, 2,849 g.

CONCLUSION:

In twin pregnancies, fetal ultrasound biometry measurements and growth parameters show a significant correlation with gestational age.     

Growth perturbations in a phenotype with rapid fetal growth preceding preterm labor and term birth

The variability in fetal growth rates and gestation duration in humans is not well understood. Of interest are women presenting with an episode of preterm labor and subsequently delivering a term neonate, who is small relative to peers of similar gestational age. To further understand these relationships, fetal growth patterns predating an episode of preterm labor were investigated. Retrospective analysis of fetal biometry assessed by serial ultrasound in a prospectively studied sample of pregnancies in Santiago, Chile, tested the hypothesis that fetal growth patterns among uncomplicated pregnancies (n = 3,706) and those with an episode of preterm labor followed by term delivery (n = 184) were identical across the time intervals 16–22 weeks, 22–28 weeks, and 28–34 weeks in a multilevel mixed‐effects regression. The hypothesis was not supported. Fetal weight growth rate was faster from 16 weeks among pregnancies with an episode of preterm labor (P < 0.05), declined across midgestation (22–28 weeks, P < 0.05), and rebounded between 28 and 34 weeks (P = 0.06). This was associated with perturbations in abdominal circumference growth and proportionately larger biparietal diameter from 22 gestational weeks (P = 0.03), greater femur (P = 0.01), biparietal diameter (P = 0.001) and head circumference (P = 0.02) dimensions relative to abdominal circumference across midgestation (22–28 weeks), followed by proportionately smaller femur diaphyseal length (P = 0.02) and biparietal diameter (P = 0.03) subsequently. A distinctive rapid growth phenotype characterized fetal growth preceding an episode of preterm labor among this sample of term‐delivered neonates. Perturbations in abdominal circumference growth and patterns of proportionality suggest an altered growth strategy pre‐dating the preterm labor episode. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.     

不同妊娠状态下孕妇外周血中游离胎儿DNA定量分析

目的对不同妊娠状态下孕妇外周血中游离胎儿DNA(f DNA)定量分析,确定其平均浓度及临床参考值范围,初步探讨在不同妊娠状态下母血中f DNA的浓度变化,为临床应用提供科学依据。方法从孕妇外周血浆中提取fDNA,用实时荧光定量聚合酶链反应(FQ-PCR)方法检测其中Y性别决定区的SRY基因。结果在正常早期的孕妇组38例血浆标本中有32例检测到SRY基因,其平均浓度149.25拷贝数/ml,参考值范围为33.28~265.22拷贝数/ml;在正常晚期的孕妇组32例血浆标本中全部检测到SRY基因,其平均浓度为212.14拷贝数/ml,参考值范围为142.76~281.52拷贝数/ml;在晚期患有子痫前期的孕妇30例血浆标本中全部检测到SRY基因,其平均浓度为678.70拷贝数/ml,参考值范围为595.01~726.40拷贝数/ml。实验数据用单因素方差分析,组间差异显著性检验用LSD-t检验。妊娠晚期孕妇血浆中f DNA的含量较妊娠早期升高,约为1.4倍,有统计学意义(P<0.01);晚期患子痫前期的孕妇血浆f DNA的水平是同期正常对照组的3.9倍,有统计学意义(P<0.01)。结论1.用FQ-PCR法最早在孕48天孕妇外周血中即可检测到fDNA。2.随着妊娠的进展孕妇血浆中f DNA的含量升高。3.晚期患子痫前期孕妇其血浆f DNA的水平是同期正常对照组的3.9倍,有统计学意义(P<0.01)。4.f DNA在进行无创伤性产前诊断中有重要价值。     

Sonographic quantitative analysis of the heart in the third trimester of gestation

Summary The fetal heart was studied with transabdominal sonography in 40 single normal pregnancies to analyze the increase of cardiac length and width (major longitudinal and transverse diameters of the heart) during the third trimester. Relationships between the cardiac data and fetal age, femur length and biparietal diameter (BPD) were explored by allometry and linear regression analysis. The length and width of the heart could be measured reproducibly in the 4-chamber view of the heart. This study verified that the heart grows very rapidly during the third trimester (positive allometry). The linear increase of the fetal heart shows a strong and significant correlation with the increase of both femur length and BPD. This suggests that non invasive analysis of cardiac data can be useful for prenatal detection of congenital heart disease or for the assessment of gestational age.This work was supported by the Brazilian agency CNPq (Grant number 50.00.427/91-7)     

13—41周胎儿11项生长发育指标的研究

对１３￣３５周正常胎儿及３６￣４１周的正常新生儿测身长、体重、头围、胸围、腹围、上臂围、顶臀长、双顶径、足底长９项生长发育指标，１３￣３５周胎儿加测右肱骨长、股骨长。体重于２３￣３７周增长加快，腹围、足底长于２８￣３６周增长最快，双顶径于２３￣２７周增长最快，３７周后各项指标增长均缓慢。２６周时体重、身长、双顶径、头围、胸围、腹围、顶臂长有一个增长高峰。３５￣３６周时除顶臂长外其它又有一个增长高峰     

Spontaneous fetal loss rates in a non-selected population

The objective of this work was to determine the rate of spontaneous fetal loss up to 28 weeks of gestation in uncomplicated pregnancies of a low-risk population after sonographically identified intact intrauterine pregnancy during the first trimester. Transvaginal ultrasounds were given to 2,534 women at between six and 12 weeks of gestation. Inclusion criteria were a positive fetal cardiac activity and no antecedent signs of vaginal bleeding. Gestational age was confirmed by measurement of the crown-rump length and/or biparietal diameter (BIP). Patients were followed until delivery or up to a fetal loss. The mean fetal loss rate between 12 and 28 weeks was 3.86% (n = 99). Fetal loss increased with maternal age: fetal loss rate under 20 yr: 2.94% (OR 0.75; CI 0.23-2. 46), 20-24 yr: 3.20% (OR 0.77; CI 0.48-1.23), 25-29 yr: 3.39% (OR 0.77; CI 0.50-1.19), 30-34 yr: 3.89% (OR 1.01; CI 0.59-1.71), 35-39 yr: 7.82% (OR 2.13; CI 1.04-4.32), 40-45 y: 50% (OR 13.84; CI 6.67-28.72) and > 45 yr: 50% (OR 13.05; CI 1.96-86.71) respectively. The frequency of spontaneous fetal loss before 28 weeks gestation was assessed systematically in a low-risk population. There was a very clear correlation with advancing maternal age. These data now can be used as background loss rate information for evaluating the safety of invasive prenatal diagnosis, and they will be more valid for this purpose than the available data taken from selected cohorts of women, such as those from hospital clinics or from infertility programs.     

Spontaneous fetal loss rates in a non‐selected population

The objective of this work was to determine the rate of spontaneous fetal loss up to 28 weeks of gestation in uncomplicated pregnancies of a low‐risk population after sonographically identified intact intrauterine pregnancy during the first trimester. Transvaginal ultrasounds were given to 2,534 women at between six and 12 weeks of gestation. Inclusion criteria were a positive fetal cardiac activity and no antecedent signs of vaginal bleeding. Gestational age was confirmed by measurement of the crown‐rump length and/or biparietal diameter (BIP). Patients were followed until delivery or up to a fetal loss. The mean fetal loss rate between 12 and 28 weeks was 3.86% (n = 99). Fetal loss increased with maternal age: fetal loss rate under 20 yr: 2.94% (OR 0.75; CI 0.23–2. 46), 20–24 yr: 3.20% (OR 0.77; CI 0.48–1.23), 25–29 yr: 3.39% (OR 0.77; CI 0.50–1.19), 30–34 yr: 3.89% (OR 1.01; CI 0.59–1.71), 35–39 yr: 7.82% (OR 2.13; CI 1.04–4.32), 40–45 y: 50% (OR 13.84; CI 6.67–28.72) and > 45 yr: 50% (OR 13.05; CI 1.96–86.71) respectively. The frequency of spontaneous fetal loss before 28 weeks gestation was assessed systematically in a low‐risk population. There was a very clear correlation with advancing maternal age. These data now can be used as background loss rate information for evaluating the safety of invasive prenatal diagnosis, and they will be more valid for this purpose than the available data taken from selected cohorts of women, such as those from hospital clinics or from infertility programs. © 2001 Wiley‐Liss, Inc.     

贵州四个民族胎儿宫内发育速率监测

研究贵州四民族胎儿宫内发育情况。方法：对汉、侗、布依、苗族中１３３５ 周正常胎儿及３６４１ 周正常新生儿共４０６０ 例测身长、体重、头围、胸围、腹围、上臂围、顶臀长、双顶径、足底长。１３３５ 周者加测右肱骨、股骨长。结果各族胎儿体格大小稍有差别，其共同规律为：身长、顶臀长、头围、双顶径２８ 周前增长快于２８ 周后。体重、腹围２６ 周后增长加快。３７ 周后各项指标增长减慢。各民族均有两次高峰增长期，分别在２６２８ 周（有顶臀长、体重、腹围增长快） 及３４３５ 周（ 有身长、体重、腹围、双顶径增长快，围产保健应掌握生长发育规律，加强高峰期监护。     

A morphometric study of suprarenal gland development in the fetal period

Purpose

The present study’s purpose was to examine the morphometric development of the suprarenal gland using anatomic dissection methods during the fetal period.

Methods

This study was performed on 172 human fetuses (76 males and 96 females) and 344 fetal suprarenal glands obtained from ages 9–40?weeks of gestation with no external pathology or anomaly. Fetuses were divided into 4 groups between gestational ages as follows: Group 1, 9–12?weeks (first trimester); Group 2, 13–25?weeks (second trimester); Group 3, 26–37?weeks (third trimester); and Group 4, 38–40?weeks (full term). Also, the fetuses were grouped into monthly cohorts: 9–12?weeks 3rd month, 13–16?weeks 4th month, 17–20?weeks 5th month, 21–24?weeks 6th month, 25–28?weeks 7th month, 29–32?weeks 8th month, 33–36?weeks 9th month, and 37–40?weeks 10th month. The suprarenal glands were dissected in the abdominal cavity. The dimensions (width, length, and thickness), volumes and weights of the suprarenal glands were evaluated. The ratio of the fetal suprarenal gland weight/fetal body weight, the ratio of the fetal suprarenal gland volume/fetal kidney volume, and the ratio of the fetal suprarenal gland dimensions/fetal kidney dimensions were evaluated.

Results

Mean values and standard deviations of all parameters according to gestational weeks and trimesters were calculated. It is found that all parameters increase with gestational age. There was significant correlation between gestational age and all parameters (p?p?>?0.05). There was no difference between the right and left sides of parameters except the thickness of the suprarenal glands. The left suprarenal glands were thicker than the right. The ratio of suprarenal volumes to kidney volumes was determined, and we observed that the ratio decreased during the fetal period.

Conclusions

We believe that the results obtained from this study will be beneficial in understanding the development of suprarenal glands and also contribute to future studies in obstetrics, perinatology, and fetopathology.     

Ultrasonography-based Fetal Weight Estimation: Finding an Appropriate Model for an Indian Population

Background

Very limited information is available regarding the accuracy and applicability of various ultrasonography parameters [abdominal circumference (AC), biparietal diameter (BPD), femur length (FL), and head circumference (HC)]-based fetal weight estimation models for Indian population. The objective of this study was to systematically evaluate commonly used fetal weight estimation models to determine their appropriateness for an Indian population.

Prenatal genetic diagnosis from maternal blood: simultaneous immunophenotyping and FISH of fetal nucleated erythrocytes isolated by negative and positive magnetic activated cell sorting

Fetal nucleated red blood cells (nRBCs) are rare in maternal circulation, but their presence constitutes a potential source of non-invasive prenatal genetic diagnosis. This study was undertaken to establish a non-invasive prenatal genetic diagnosis method using isolated fetal nRBCs. A multi-step method including triple density gradient and magnetic activated cell sorting (MACS) using CD45 and CD71, cytospin centrifugation, K-B staining, and glycophorin A-immuno fluorescence in situ hybridization (GPA-immuno FISH) was performed. The study population included 65 patients from 8 to 41 weeks of gestation, and fetal nRBC was separated from all cases. The number of fetal nRBCs retrieved was 12.8 +/- 2.7 in 8 to 11 gestational weeks, 15.2 +/- 6.5 in 12 to 18 gestational weeks, 16.4 +/- 6.5 in 19 to 23 gestational weeks, 10.6 +/- 3.2 in 24 to 28 gestational weeks, and 5.5 +/- 1.9 in 35 to 41 gestational weeks: the mean number of nRBCs collected from 20 ml of maternal peripheral blood was 13.7 +/- 6.2. The highest value of yield was 45.6% from 12 to 18 weeks gestation. The fetal sex determination confirmed by amniocentesis or chorionic villus sampling showed 100% sensitivity and 91.7% specificity for males; 91.7% sensitivity and 100% specificity for females. We showed that fetal cells can be reliably enriched from maternal blood and that they can be used for detecting specific chromosomes by FISH with a specificity superior to current non-invasive methods.     

Size and location of thyroid gland in the fetal period

Purpose

The present study’s purpose was to examine the size and location of the thyroid gland using anatomic dissection methods on fetal cadavers.

Methods

This study was performed on 200 spontaneously aborted human fetuses (100 males and 100 females) aged between 9 and 40 weeks of gestation. Fetuses without any external and internal pathology or anomaly were included in this study. Fetuses were divided into four groups based on gestational ages as follows: first group 9–12 weeks (first trimester), second group 13–25 weeks (second trimester), third group 26–37 weeks (third trimester) and fourth group 38–40 weeks (full term). The fetuses were also grouped into monthly cohorts as follows: 9–12 weeks, 3rd month; 13–16 weeks, 4th month; 17–20 weeks, 5th month; 21–24 weeks, 6th month; 25–28 weeks, 7th month; 29–32 weeks, 8th month; 33–36 weeks, 9th month; and 37–40 weeks, 10th month. The anterior necks of fetuses were dissected and the thyroid glands exposed. Vertebral and laryngeal levels and the dimensions (width, length, thickness and weight) of the fetal thyroid glands were determined by anatomical dissection methods. The dimensions and ratios of the fetal thyroid gland (weight/fetal body weight) were evaluated.

Results

The mean values and standard deviations of all parameters by gestational weeks, months, and trimesters were calculated. It was found that all parameters increased with gestational age. No significant differences were observed between genders in all parameters (P > 0.05). There were no significant differences between the right and the left sides for parameters of the thyroid glands. The levels of the superior poles of the thyroid lobes were located at the cervical (C) C1–C3 vertebral bodies. The levels of the inferior poles of the thyroid lobes were located at C4–C5 vertebral bodies. The levels of the superior poles of thyroid lobes were located between the upper ½ and lower ½ of the thyroid cartilage or cricoid cartilage. The levels of the inferior poles of the thyroid lobes were located between the second and sixth tracheal rings. The distance between the superior poles of the thyroid gland and the hyoid bone increased throughout the fetal period. The dimensions of fetal thyroid glands increased with gestational age. The ratio between thyroid gland weights and fetal body weights was unchanged during the fetal period.

Conclusions

We believe that the results obtained from this study will be useful in monitoring thyroid glands in the intrauterine period as well as recognizing early diagnosis and treatment of thyroid anomalies. It will also contribute to future studies in obstetrics, perinatology, and fetopathology.     

Sonographic measurement of the fetal pancreas in women with gestational diabetes

IntroductionMaternal glycemic state is positively correlated with fetal insulin secretion. Randomized control studies have shown that treatment during pregnancy inhibits to some degree this glycemic effect. Our study aimed to assess fetal pancreas size in a population of treated mothers with gestational diabetes.Material and methodsA cross-sectional, prospective observational study was conducted. Pregnant women at 19–36 weeks of gestation with pre-gestational diabetes receiving insulin therapy or with gestational diabetes receiving either insulin or oral hypoglycemic therapy were recruited. The fetal pancreas circumference was measured and compared to the normal reference range. The Z score of the difference between measured and normal predicted mean pancreas circumference, the regression analysis throughout pregnancy, and the correlation between estimated fetal weight centile and pancreas circumference were calculated.ResultsNinety-one women who had gestational diabetes and thirty-four women who had pre-gestational diabetes were included in the study. For both groups, fetal pancreas circumference correlated significantly with abdominal circumference, estimated fetal weight and gestational age. The mean Z score between the predicted pancreas circumference in the group of women diagnosed with gestational diabetes and the predicted pancreas circumference in a normal population peaked at around 24 weeks of gestation (1.1) and decreased gradually afterward to a value of zero at 37 weeks. The mean Z score between the predicted pancreas circumference in the group of women with pre-gestational diabetes and the predicted pancreas circumference in a normal population constantly decreased with duration of pregnancy. It was positive until the 25^th week of gestation and then presented negative values towards the term.ConclusionsThe presented preliminary data suggest a possible correlation between glycemic control treatment, pancreas size, and gestational age.     

Correlation between first trimester fetal bone length and maternal serum pregnancy-associated plasma protein-A (PAPP-A)

BACKGROUND: Pregnancy-associated plasma protein-A (PAPP-A) is produced by the embryo and placenta during pregnancy, and its maternal serum concentrations are related to subsequent fetal growth. Evidence from animal models and in vitro experiments suggests that PAPP-A is particularly involved in the regulation of bone development. The aim of this study was to assess the correlation between late first trimester fetal bone length and maternal serum levels of PAPP-A. METHODS: In a cross-sectional observational study, ultrasound measurements of fetal long bones and fluorimetric immunoassays for maternal serum PAPP-A were performed in 514 singleton pregnancies at 10-14 weeks of gestation. RESULTS: There were 501 uncomplicated pregnancies. There were significant correlations between PAPP-A values and length of humerus, femur and tibia [r values 0.12 (P = 0.01), 0.11 (P = 0.01) and 0.10 (P = 0.03), respectively]. The association with the length of ulna and foot did not reach statistical significance (r values 0.08 and -0.03, respectively). CONCLUSIONS: Maternal serum PAPP-A levels at 10-14 weeks of gestation are significantly associated with the length of fetal long bones such as humerus, femur and tibia. This provides further evidence that PAPP-A may be involved in the regulation of bone development.     

FGFR3 related skeletal dysplasias diagnosed prenatally by ultrasonography and molecular analysis: presentation of 17 cases

Fibroblast Growth Factor Receptor 3 (FGFR3) related skeletal dysplasias are caused by mutations in the FGFR3 gene that result in increased activation of the receptors causing alterations in the process of endochondral ossification in all long bones, and include achondroplasia, hypochondroplasia, thanatophoric dysplasia, and SADDAN. Reports of prenatal diagnosis of FGFR3 related skeletal dysplasias are not rare; however, the correlation between 2nd trimester ultrasonographic findings and underlying molecular defect in these cases is relatively poor. There is a need for specific ultrasound (U/S) predictors than can distinguish lethal from non-lethal cases and aid an earlier prenatal diagnosis. Here we present one familial and 16 sporadic cases with FGFR3 related skeletal dysplasia, and we evaluate biometric parameters and U/S findings consistent with the diagnosis of skeletal dysplasia. U/S scan performed even at the 18th week of gestation can indicate a decreased rate of development of the femora (femur length (FL) <5th centile), while the mean gestational age at diagnosis is still around the 26th week. The utility of other biometric parameters and ratios is discussed (foot length, BPD, HC, FL/foot, and FL/AC). Prenatal cytogenetic and molecular genetic analyses were performed. A final diagnosis was reached by molecular analysis. In two cases of discontinued pregnancy, fetal autopsy led to a phenotypic diagnosis and confirmed the prenatal prediction of lethality. We conclude that the combination of U/S and molecular genetic approach is helpful for establishing an accurate diagnosis of FGFR3-related skeletal dysplasias in utero and subsequently for appropriate genetic counselling and perinatal management.     

Timing is everything: A reconsideration of fetal growth velocity patterns identifies the importance of individual and sex differences

Fetal growth has been posited to follow a “timing hypothesis” sequence in which the second trimester favors a single growth velocity peak in body length and the third trimester accommodates a single growth velocity peak in weight accrual. To our knowledge, this proposition has never been tested with high‐frequency longitudinal ultrasound data from normally growing human fetuses. The present study examined whether fetal growth in leg length had its peak velocity at or about 20–26 gestational weeks and declined subsequently and whether estimated fetal weight velocity was maximal at or about 33 weeks and declined subsequently; if the greatest acquisition of leg length occurred in the second trimester and weight in the third trimester; and if birth outcomes reflected these relationships. The data in this study included approximately weekly longitudinal ultrasound data collected from 44 maternal/fetal pairs in Brussels, Belgium. Diaphyseal lengths of the femur and tibia provided information on leg growth and estimated fetal weight was assessed from the biparietal and occipital‐frontal head diameters and transverse and anterior–posterior diameters of the abdomen. Growth patterns were investigated from individual growth curves derived from daily growth velocity z‐scores. Paired t‐tests compared individuals' trimestral increments in leg length and fetal weight. Least‐squares regression models employing the robust procedure for repeated measurements were used to test for relationships between trimester, size, growth rates, and birth outcome, controlling for day of measurement, sex, maternal smoking, and gestational age at birth. The normal fetuses in this study grew by pulsatile patterns of leg and estimated weight acquisition, not a single peak and decline process. Greater incremental growth in estimated fetal weight occurred during the second trimester and leg length in the third trimester. Individual and sex effects were significant in growth velocity patterns. Girls grew with greater synchrony between leg and weight growth and were accelerated by comparison with boys, with faster leg growth predicting lower ponderal index by the second trimester. Birth outcomes were sex‐specific in timing effects and predictive variables. These results support the importance of sex‐specific analyses, reemphasize the common notion that girls grow faster than boys, and direct attention to cross‐talk between energy resources and growth. Am. J. Hum. Biol. 15:667–680, 2003. © 2003 Wiley‐Liss, Inc.     

Infants thinner at birth exhibit smaller kidneys for their size in late gestation in a sample of fetuses with appropriate growth

Fetal ultrasound measurements were employed to investigate the relationship between weight and ponderal index at birth and kidney size during the second (23 weeks) and third (32 weeks) trimesters of pregnancy in a sample of 25 normally growing fetuses. Kidney volume and kidney volume / fetal weight ratio at 32 weeks are significantly and positively related to both weight and ponderal index at birth, controlling for sex, gestational age at birth, and day of ultrasound measurement. A second‐degree polynomial relationship approximates the predictability of kidney volume fetal weight ratio at 23 weeks to that at 32 weeks, demonstrating shifting growth rates in fetal organ and body growth relationships during midgestation. Sex and parental size are suggested as contributing to these patterns. Females have a surge in renal growth between 23 and 32 weeks to catch up to earlier growing males, and maternal weight significantly predicts incremental growth in kidney volume and the kidney volume / fetal weight ratio at 32 weeks of gestation. The observation that fetuses relatively thin at birth have relatively smaller kidneys for their size in late gestation suggests that the influence of maternal weight on birth outcome may act through organ growth. Am. J. Hum. Biol. 14:398–406, 2002. © 2002 Wiley‐Liss, Inc.