Occipital Frontal Diameter Research Articles

Early Protein Intake Influences Neonatal Brain Measurements in Preterms: An Observational Study.

Introduction: To limit extrauterine growth restriction, recent guidelines on nutrition of preterm neonates recommended high protein intake since the first day of life (DOL). The impact of this nutritional strategy on the brain is still controversial. We aimed to evaluate the effects of protein intake on early cerebral growth in very low birth weight newborns.Materials and Methods: We performed serial cranial ultrasound (cUS) scans at 3–7 DOL and at 28 DOL in very low birth weight newborns consecutively observed in the neonatal intensive care unit. We analyzed the relation between protein intake and cerebral measurements at 28 DOL performed by cUS.Results: We enrolled 100 newborns (gestational age 29 ± 2 weeks, birth weight 1,274 ± 363 g). A significant (p < 0.05) positive correlation between enteral protein intake and biparietal diameter (r = 0.490**), occipital–frontal diameter (r = 0.608**), corpus callosum (length r = 0.293*, genu r = 0.301*), caudate head (right r = 0.528**, left r = 0.364**), and cerebellum (transverse diameter r = 0.440**, vermis height r = 0.356**, vermis width r = 0.377**) was observed at 28 DOL. Conversely, we found a significant negative correlation of protein intake given by parenteral nutrition (PN) with biparietal diameter (r = −0.524**), occipital–frontal diameter (r = −0.568**), body of corpus callosum (r = −0.276*), caudate head (right r = −0.613**, left r = −0.444**), and cerebellum (transverse diameter r = −0.403**, vermis height r = −0.274*, vermis width r = −0.462**) at 28 DOL. Multivariate regression analysis showed that measurements of occipital–frontal diameter, caudate head, and cerebellar vermis at 28 DOL depend positively on protein enteral intake (r = 0.402*, r = 0.305*, and r = 0.271*) and negatively by protein parenteral intake (r = −0.278*, r = −0.488*, and r = −0.342*).Conclusion: Brain development in neonatal life depends on early protein intake. High protein intake affects cerebral structures' measurements of preterm newborn when administered by PN. Positive impact on brain development encourages the administration of recommended protein intake mainly by enteral nutrition.

603: Prediction of labor dystocia indicated primary cesarean delivery in women undergoing induction of labor

Induction of labor (IOL) is one of the most frequent interventions in obstetrics. Our objective was to determine if fetal biometric parameters obtained near term and antenatal factors predicted labor dystocia-indicated PCD in women who experienced IOL. Analysis of a prospective multicenter NIH-sponsored National Fetal Growth Study-Singletons. Women with a non anomalous,uncomplicated singleton gestation who underwent IOL at ≥37 0/7 weeks were included. Serial sonographic exams with the final exam at 37.5 +/- 1.9 weeks were performed. Estimated fetal weight (EFW), individual biometric parameters, derived measures of fetal asymmetry (i.e biparietal diameter (BPD) - abdominal diameter (AD) difference), and amniotic fluid deepest vertical pocket measured at the last scan and categorized as < 10th, 10th- 90th(reference), >90th percentiles were compared for women who had labor dystocia-indicated PCD versus spontaneous vaginal delivery. Multivariable logistic regression analysis was conducted to assess the association of fetal biometric parameters with labor dystocia-indicated PCD. A model with optimal predictive ability measured by area under the curve (AUC) was determined. Of 1,472 pregnancies analyzed, 396 (28.3%) underwent IOL. Compared to the reference group, EFW >90thpercentile tripled the odds of labor dystocia-indicated PCD (Table 1). The best predictive model for labor dystocia-indicated PCD (AUC 0.89) was composed of maternal gestational weight gain (OR 1.11; 95% CI 1.02, 1.22), multiparity(OR 0.01; 95% CI 0.00, 0.15), occipital-frontal diameter >90thpercentile (OR 16.17; 95% CI 1.45, 180.18), humerus length >90thpercentile (OR 0.09; 95% CI 0.01, 0.70), and EFW >90thpercentile (OR 11.63; 95% CI 1.97, 68.75). Sensitivity, specificity, positive and negative predictive values were 80%, 80%, 39%, and 97.6%, respectively for this model. Specific fetal biometric parameters along with multiple antenatal factors were relevant predictors of labor dystocia-indicated PCD in women undergoing IOL, and this model might have potential utility in clinical practice.

Small head size and delayed body weight growth in wild Japanese monkey fetuses after the Fukushima Daiichi nuclear disaster

To evaluate the biological effect of the Fukushima Daiichi nuclear disaster, relative differences in the growth of wild Japanese monkeys (Macaca fuscata) were measured before and after the disaster of 2011 in Fukushima City, which is approximately 70 km from the nuclear power plant, by performing external measurements on fetuses collected from 2008 to 2016. Comparing the relative growth of 31 fetuses conceived prior to the disaster and 31 fetuses conceived after the disaster in terms of body weight and head size (product of the occipital frontal diameter and biparietal diameter) to crown-rump length ratio revealed that body weight growth rate and proportional head size were significantly lower in fetuses conceived after the disaster. No significant difference was observed in nutritional indicators for the fetuses’ mothers. Accordingly, radiation exposure could be one factor contributed to the observed growth delay in this study.

Automatic image quality assessment and measurement of fetal head in two-dimensional ultrasound image.

Owing to the inconsistent image quality existing in routine obstetric ultrasound (US) scans that leads to a large intraobserver and interobserver variability, the aim of this study is to develop a quality-assured, fully automated US fetal head measurement system. A texton-based fetal head segmentation is used as a prerequisite step to obtain the head region. Textons are calculated using a filter bank designed specific for US fetal head structure. Both shape- and anatomic-based features calculated from the segmented head region are then fed into a random forest classifier to determine the quality of the image (e.g., whether the image is acquired from a correct imaging plane), from which fetal head measurements [biparietal diameter (BPD), occipital-frontal diameter (OFD), and head circumference (HC)] are derived. The experimental results show a good performance of our method for US quality assessment and fetal head measurements. The overall precision for automatic image quality assessment is 95.24% with 87.5% sensitivity and 100% specificity, while segmentation performance shows 99.27% ([Formula: see text]) of accuracy, 97.07% ([Formula: see text]) of sensitivity, 2.23mm ([Formula: see text]) of the maximum symmetric contour distance, and 0.84mm ([Formula: see text]) of the average symmetric contour distance. The statistical analysis results using paired [Formula: see text]-test and Bland-Altman plots analysis indicate that the 95% limits of agreement for inter observer variability between the automated measurements and the senior expert measurements are 2.7mm of BPD, 5.8mm of OFD, and 10.4mm of HC, whereas the mean differences are [Formula: see text], [Formula: see text], and [Formula: see text], respectively. These narrow 95% limits of agreements indicate a good level of consistency between the automated and the senior expert's measurements.

Fetal biometric parameters: Reference charts for a non-selected risk population from Uberaba, Brazil.

ObjectiveTo establish reference charts for fetal biometric parameters in a non-selected risk population from Uberaba, Southeast of Brazil.MethodsA retrospective cross-sectional study was performed among 5656 non-selected risk singleton pregnant women between 14 and 41 weeks of gestation. The ultrasound exams were performed during routine visits of second and third trimesters. Biparietal diameter (BPD) was measured at the level of the thalami and cavum septi pellucidi. Head circumference (HC) was calculated by the following formula: HC = 1.62*(BPD + occipital frontal diameter, OFD). Abdominal circumference (AC) was measured using the following formula: AC = (anteroposterior diameter + transverse abdominal diameter) × 1.57. Femur diaphysis length (FDL) was obtained in the longest axis of femur without including the distal femoral epiphysis. The estimated fetal weight (EFW) was obtained by the Hadlock formula. Polynomial regressions were performed to obtain the best-fit model for each fetal biometric parameter as the function of gestational age (GA).ResultsThe mean, standard deviations (SD), minimum and maximum of BPD (cm), HC (cm), AC (cm), FDL (cm) and EFW (g) were 6.9 ± 1.9 (2.3 – 10.5), 24.51 ± 6.61 (9.1 – 36.4), 22.8 ± 7.3 (7.5 – 41.1), 4.9 ± 1.6 (1.2 – 8.1) and 1365 ± 1019 (103 – 4777), respectively. Second-degree polynomial regressions between the evaluated parameters and GA resulted in the following formulas: BPD = –4.044 + 0.540 × GA – 0.0049 × GA2 (R2 = 0.97); HC= –15.420 + 2.024 GA – 0.0199 × GA2 (R2 = 0.98); AC = –9.579 + 1.329 × GA – 0.0055 × GA2 (R2 = 0.97); FDL = –3.778 + 0.416 × GA – 0.0035 × GA2 (R2 = 0.98) and EFW = 916 – 123 × GA + 4.70 × GA2 (R2 = 0.96); respectively.ConclusionReference charts for the fetal biometric parameters in a non-selected risk population from Uberaba, Southeast of Brazil, were established.

Implementing Methodology for Teaching Initial Radiology for First Year Radiology Residents in on Obstetrical Ultrasound

Introduction of a new teaching methodology in obstetrical ultrasound especially aimed at beginners, to enable initial radiology residents toperform a complete Doppler Ultrasound after one month of internship. Obstetrical ultrasound learning occurs in the first and second years of residence in Radiology. First year residents usually have little or no experience in ultrasound before their obstetrical stage. During the first year, the purpose of internship is to perform a complete obstetrical ultrasound exam with dopplerfluxometry. In view of the inexperience of these residents, we created a teaching methodology in 2014; therefore, three full years of use have been completes. The teaching sequence was: Step 1: Only biometry was introduced, following recommended international guidelines: head circumference, bi parietal diameter, occipital frontal diameter; abdominal circumference, femur length, humerus length. Step 2: After a satisfactory performance in biometry resident are introduced to the techniques of checking the spine, diaphragm, four heart chambers and placenta, both for measurement and grading. Step3: After residents perform adequately for steps one and two, the move to step three, which consists in the performance of dopplerfluxometry for determination of heart beating, umbilical artery, median cerebral artery and uterine artery. Step 4: After a satisfactory step three, residents move to estimation of amniotic fluid index, cervix length, nuchal fold, lateral atrium cerebral, pelvis renal diameter and details of fetal face. Percentile 10 : no capacity to perform complete steps one and two Percentile 25: capacity to perform steps one and two but incomplete step three. Percentile 50: Capacity to perform steps one, two and three and part of step four. Percentile 75: Capacity to perform all steps. In 2014, 19 first year residents were subjected to the method, in 2015 26 first year residents, in 2016 28 residents, with percentile distribution as shown in table 1.Table 1: Relationship between number of students by year correlated with percentiles PercentilesYears 10255075201412 13320153 41722016 2619 2” The new method proved to be effective as a first approach for teaching initiating residents. As a result, about 80% of new residents could perform a complete obstetrical dopplerfluxometry ultrasound test. After a complete year of residence, we checked the opinion of the students and found that 80% of them declared themselves capable of realizing an obstetrical examination with dopplerfluxometry ultrasound examination. This agreed with our evaluation about their performance.

Second-Trimester Ultrasound as a Tool for Early Detection of Fetal Alcohol Spectrum Disorders.

Early detection of fetal alcohol spectrum disorders (FASDs) is desirable to allow earlier and more comprehensive interventions to be initiated for the mother and infant. We examined prenatal ultrasound as an early method of detecting markers of the physical features and neurobehavioral deficits characteristic of FASD. A longitudinal cohort of pregnant women in Ukraine was recruited as part of the Collaborative Initiative on Fetal Alcohol Spectrum Disorders. Women were enrolled into a moderately to heavy-alcohol-exposed group or a low- or no-alcohol exposure group and were followed to pregnancy outcome. In the second trimester, a fetal ultrasound was performed to measure transverse cerebellar diameter, occipital frontal diameter (OFD), caval-calvarial distance, frontothalamic distance (FTD), interorbital distance (IOD), outer orbital diameter, and orbital diameter (OD). Live born infants received a dysmorphological examination and a neurobehavioral evaluation using the Bayley Scales of Infant Development. These data were used to classify infants with respect to FASD. Comparisons were made on the ultrasound measures between those with and without features of FASD, adjusting for gestational age at ultrasound and maternal smoking. A total of 233 mother/child dyads were included. Children classified as FASD had significantly longer IOD and lower FTD/IOD, OFD/IOD, and FTD/OD ratios (p<0.05). Children with a Bayley score <85 had significantly shorter FTD, longer IOD, lower OFD/IOD, and FTD/IOD ratios (p<0.05). In general, mean differences were small. Ultrasound variables alone predicted <10% of the variance in the FASD outcome. Some ultrasound measurements were associated with FASD, selected facial features of the disorder, and lower neurobehavioral scores. However, mean differences were relatively small, making it difficult to predict affected children based solely on these measures. It may be advantageous to combine these easily obtained ultrasound measures with other data to aid in identifying high risk for an FASD outcome.

Growth trajectories of the human embryonic head and periconceptional maternal conditions.

Can growth trajectories of the human embryonic head be created using 3D ultrasound (3D-US) and virtual reality (VR) technology, and be associated with second trimester fetal head size and periconceptional maternal conditions? Serial first trimester head circumference (HC) and head volume (HV) measurements were used to create reliable growth trajectories of the embryonic head, which were significantly associated with fetal head size and periconceptional maternal smoking, age and ITALIC! in vitro fertilization (IVF)/intra-cytoplasmic sperm injection (ICSI) treatment. Fetal growth is influenced by periconceptional maternal conditions. We selected 149 singleton pregnancies with a live born non-malformed fetus from the Rotterdam periconception cohort. Bi-parietal diameter and occipital frontal diameter to calculate HC, HV and crown-rump length (CRL) were measured weekly between 9 + 0 and 12 + 6 weeks gestational age (GA) using 3D-US and VR. Fetal HC was obtained from second trimester structural anomaly scans. Growth trajectories of the embryonic head were created with general additive models and linear mixed models were used to estimate associations with maternal periconceptional conditions as a function of GA and CRL, respectively. A total of 303 3D-US images of 149 pregnancies were eligible for embryonic head measurements (intra-class correlation coefficients >0.99). Associations were found between embryonic HC and fetal HC ( ITALIC! ρ = 0.617, ITALIC! P < 0.001) and between embryonic HV and fetal HC ( ITALIC! ρ = 0.660, ITALIC! P < 0.001) in ITALIC! Z-scores. Maternal periconceptional smoking was associated with decreased, and maternal age and IVF/ICSI treatment with increased growth trajectories of the embryonic head measured by HC and HV (All ITALIC! P < 0.05). The consequences of the small effect sizes for neurodevelopmental outcome need further investigation. As the study population consists largely of tertiary hospital patients, external validity should be studied in the general population. Assessment of growth trajectories of the embryonic head may be of benefit in future early antenatal care. This study was funded by the Department of Obstetrics and Gynaecology, Erasmus MC University Medical Centre and Sophia Foundation for Medical Research, Rotterdam, The Netherlands (SSWO grant number 644). No competing interests are declared.

Registration-Based Segmentation of Three-Dimensional Ultrasound Images for Quantitative Measurement of Fetal Craniofacial Structure

Segmentation of a fetal head from three-dimensional (3-D) ultrasound images is a critical step in the quantitative measurement of fetal craniofacial structure. However, two main issues complicate segmentation, including fuzzy boundaries and large variations in pose and shape among different ultrasound images. In this article, we propose a new registration-based method for automatically segmenting the fetal head from 3-D ultrasound images. The proposed method first detects the eyes based on Gabor features to identify the pose of the fetus image. Then, a reference model, which is constructed from a fetal phantom and contains prior knowledge of head shape, is aligned to the image via feature-based registration. Finally, 3-D snake deformation is utilized to improve the boundary fitness between the model and image. Four clinically useful parameters including inter-orbital diameter (IOD), bilateral orbital diameter (BOD), occipital frontal diameter (OFD) and bilateral parietal diameter (BPD) are measured based on the results of the eye detection and head segmentation. Ultrasound volumes from 11 subjects were used for validation of the method accuracy. Experimental results showed that the proposed method was able to overcome the aforementioned difficulties and achieve good agreement between automatic and manual measurements.

Comparison of Fetal Biometric Values with Sonographic and 3D Reconstruction MRI in Term Gestations

We sought to compare the fetal biometric values head and abdominal circumferences, biparietal and occipital-frontal diameters, and left and right ventricular atrial diameters obtained with contemporaneous sonography and 3D MRI reconstructions in term pregnancies. A total of 107 nulliparous women evaluated as having uncomplicated pregnancies and scheduled for induction at 42 completed weeks gave their informed consent and underwent MRI and sonography within 3 hours of each other. Two single-shot fast spin-echo MRI sequences were performed with 7- and 4-mm slice thicknesses and no gap. A single observer performed MRI postprocessing to obtain biometric values. A single sonographer using a 3- to 5-MHz curvilinear transducer performed transabdominal sonography. Concordance correlation and Bland-Altman analysis of differences were performed. Concordance correlation was poor for both right (0.024) and left (0.005) ventricular atrial diameters. There were moderate concordance correlations for head (0.56) and abdominal (0.53) circumferences and biparietal diameter (0.61). Occipital-frontal diameter had fair correlation (0.27). Comparison between contemporaneous sonographic and 3D reconstructed MR images at late gestational ages shows acceptable correlation between the two techniques for head circumference, abdominal circumference, and biparietal diameter.

MR volume of the fetal cerebellum in relation to growth

To quantify fetal cerebellar growth by measuring cerebellar volumes of normal fetuses throughout gestation with MRI. A total of 93 fetuses with normal brains ranging in age from 16 to 40 gestational weeks were included in the study. Standard fetal biometric measurements were made on a three-dimensional postprocessing workstation and included the head circumference, transverse cerebellar diameter, biparietal diameter, occipital-frontal diameter, as well as cerebellar volume. The gestational ages were estimated from fetal head circumference measurements. Regression analysis was used to find the best-fit model. There is a strong correlation describing cerebellar volume and gestational age in fetuses with normal central nervous systems. A second-order polynomial regression model was found to be the most appropriate descriptor of cerebellar volume in relation to normal fetal growth. In addition, the cerebellar volume was also found to correlate strongly with the common fetal biometric measurements of transverse cerebellar diameter, biparietal diameter, and occipital-frontal diameter. Nomograms for fetal cerebellar volume with gestational age derived from head circumference measurements are presented for the first time with MRI. A normal fetal cerebellar volume growth chart is established. These results should prove helpful in defining situations of abnormal growth development and dysmorphology.

OC182: Can prenatal ultrasound detect the effects of in‐utero alcohol exposure?

Objectives: To develop ultrasound parameters for the early detection of alcohol-mediated fetal somatic and CNS maldevelopment. Maternal alcohol ingestion during pregnancy may lead to fetal alcohol spectrum disorder (FASD) which encompasses a broad range of structural abnormalities including growth impairment, cardiac and CNS abnormalities. Developmental and behavioral abnormalities parallel such structural defects. Early detection of fetuses at risk of FASD would allow earlier interventions. Methods: We performed a longitudinal prospective study from 2004 to 2006 in two sites in Ukraine. Women were screened for alcohol use using TWEAK and AUDIT questionnaires. We compared the fetuses of pregnant women with moderate-to-heavy alcohol consumption during pregnancy to those of women who drank little or no alcohol. Ultrasound evaluation of growth and specific measurements of intracranial structures including occipital frontal diameter (OFD), transverse cerebellar diameter (TCD), caval calvarial distance (CCD), outer orbital diameter (OOD), intraorbital diameter (IOD) and orbital diameter were performed during the second and third trimesters. Data from alcohol-exposed and a similar number of control fetuses were compared using ANOVA. Results: From 6745 screened subjects 84 heavy alcohol users were identified in the second trimester; 47 of these were available for comparison in the third trimester. Mothers who drank were significantly more likely to be single, use tobacco and be of lower socioeconomic status compared to controls. Significant ultrasound findings are given below, comparing exposed to control subjects using ANOVA (NS, not significant).

Determinação da idade fetal por meio da técnica ultra-sonográfica de fetometria e de morfologia fetal em cabras

Utilizaram-se 13 cabras gestantes da raça Saanen, para estudo das características da gestação a partir do 60º dia, segundo as técnicas de fetometria e avaliação morfológica fetal, utilizando-se ultra-sonografia em modo-B. Analisaram-se: diâmetro orbital (DO), diâmetro interorbital (DIO), diâmetro biorbital (DBO), diâmetro biparietal (DBP), comprimento do fêmur (CF), comprimento da tíbia (CT), comprimento do rádio (CR), diâmetro do tórax (DT), diâmetro abdominal transversal (DAT), diâmetro abdominal anteroposterior (DAP), diâmetro occípito-frontal (DOF), diâmetro transversal renal (RIMT), diâmetro longitudinal renal (RIML), comprimento da escápula (ESC), comprimento do metacarpo (MEC), medida da pelve (COX) e comprimento do úmero (CU). As médias dos valores achados foram correlacionadas com a idade fetal. As equações de regressão inversa foram criadas para cada parâmetro, sendo que DBP (R²=0,93), CF (R²=0,95), CU (R²=0,96), DO (R²= 0,84) e DAT (R²= 0,91) foram as variáveis de melhor correlação estatística, cuja equação pode ser representada pela fórmula: idade fetal = 34,5 + 4,8DBP + 9,9 CF - 7,5 CU - 2,3 DO + 6,1 DAT.

Exposure to maternal diabetes is associated with altered fetal growth patterns: A hypothesis regarding metabolic allocation to growth under hyperglycemic-hypoxemic conditions.

The prevalence of diabetes is rising worldwide, including women who grew poorly in early life, presenting intergenerational health problems for their offspring. It is well documented that fetuses exposed to maternal diabetes during pregnancy experience both macrosomia and poor growth outcomes in birth size. Less is known about the in utero growth patterns that precede these risk factor expressions. Fetal growth patterns and the effects of clinical class and glycemic control were investigated in 37 diabetic pregnant women and their fetuses and compared to 29 nondiabetic, nonsmoking maternal/fetal pairs who were participants in a biweekly longitudinal ultrasound study with measurements of the head, limb, and trunk dimensions. White clinical class of the diabetic women was recorded (A2-FR) and glycosylated hemoglobin levels taken at the time of measurement assessed glycemic control (median 6.9%, interquartile range 5.6-9.2%). No significant difference in fetal weight was found by exposure. The exposed sample had greater abdominal circumferences from 21 weeks (P < or = 0.05) and shorter legs, but greater upper arm and thigh circumferences accompanied increasing glycemia in the second trimester. In the third trimester, exposed fetuses had a smaller slope for the occipital frontal diameter (P = 0.00) and were brachycephalic. They experienced a proximal/distal growth gradient in limb proportionality with higher humerus / femur ratios (P = 0.04) and arms relatively long by comparison with legs (P = 0.02). HbA1c levels above 7.5% accompanied shorter femur length for thigh circumference after 30 gestational weeks of age. Significant effects of diabetic clinical class and glycemic control were identified in growth rate timing. These growth patterns suggest that hypoxemic and hyperglycemic signals cross-talk with their target receptors in a developmentally regulated, hierarchical sequence. The increase in fetal fat often documented with diabetic pregnancy may reflect altered growth at the level of cell differentiation and proximate mechanisms controlling body composition. These data suggest that the maternal-fetal interchange circuit, designed to share and capture resources on the fetal side, may not have had a long evolutionary history of overabundance as a selective force, and modern health problems drive postnatal sequelae that become exacerbated by increasing longevity.

Prenatal smoke exposure alters growth in limb proportions and head shape in the midgestation human fetus.

The objective of this study was to examine the effects of smoke exposure on the growth patterns of the head, limbs, and torso of the midgestation human fetus. Four hundred maternal/fetal pairs contributed to this analysis: 366 individuals were assessed cross-sectionally (87 smokers and 279 nonsmokers) at approximately 20 and 32 weeks, and 34 individuals were followed longitudinally at 23, 27, and 32 weeks (10 smokers, 24 nonsmokers). Ten body parameters were measured by fetal ultrasound. In both samples, controlling for day of measurement, smoke exposure was significantly associated with early growth acceleration in head and abdominal diameters at 20-27 weeks (P < 0.05). This was followed by altered head shape (a significantly smaller biparietal to occipital frontal diameter ratio at 32 weeks, P < 0.01), and a proximal/distal growth gradient as proportionately long arms (P < 0.05 at 27 and 32 weeks) and short legs were apparent by 32 weeks, with a significant reduction in the tibia/femur ratio (P = 0.04). These fetal body growth patterns, expressed in terms of size and proportionality, are consistent with the presence of chronic hypoxia associated with maternal smoking. The growth pattern differences identify that prenatal smoking is not merely an insult resulting in consistent size and growth rate reduction across developmental ages. Instead, smoke exposure alters the growth rate of individual body segments at variable developmental stages as the fetus experiences selective growth restriction and augmentation. We hypothesize that the growth patterns observed here reflect the unique pattern of fetal blood flow favoring upper body oxygen distribution and extraction, together with genetically based adaptive strategies that permit the fetus to adjust the timing and magnitude of its growth to local environmental resources. It is possible that dolichocephaly is a previously unappreciated marker of fetal hypoxia. Reduced tibial growth may be a good marker for shortfall and a useful proxy for the adequacy of circulating resources more generally.

Ultrasound anthropometric reliability.

Method errors and reliabilities were estimated for seven sonographic measurements in pregnancies of 106 women examined between January and July 1989. Teams of two experienced sonographers replicated the following measurements: biparietal diameter (BPD), occipital-frontal diameter (OFD), anterior-posterior diameter (APD), transabdominal distance (TAD), and femur diaphysis length (FDL). Multilevel modeling procedures were used to estimate the variance components. Significant (p < 0.01) covariates in the fixed part of the model included an increase in error with greater parity, estimated menstrual age (EMA), and maternal abdominal wall thickness (taken at the umbilicus). Intraobserver reliability ranged from 85.2% (AC) to 99.3% (FDL); interobserver reliability ranged from 80.8% (TAD) to 92.4% (FDL). Method errors, describing the expected error for 68% of the measurements taken, ranged from 0.8 mm to 7.7 mm (intraobserver) and from 1.2 mm to 7.8 mm (interobserver). These results suggest that large error components should be considered in the interpretation of the reliability of ultrasonographically obtained measurements.