Background Reliable ultrasound charts are necessary for the prenatal assessment of fetal size, yet there is a wide variation of methodologies for the creation of such charts.Objective To evaluate the methodological quality of studies of fetal biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods.Search strategy Electronic searches in MEDLINE, EMBASE and CINAHL, and references of retrieved articles.Selection criteria Observational studies whose primary aim was to create ultrasound size charts for bi-parietal diameter, head circumference, abdominal circumference and femur length in fetuses from singleton pregnancies.Data collection and analysis Studies were scored against a predefined set of independently agreed methodological criteria and an overall quality score was given to each study. Multiple regression analysis between quality scores and study characteristics was performed.Main results Eighty-three studies met the inclusion criteria. The highest potential for bias was noted in the following fields: 'Inclusion/exclusion criteria', as none of the studies defined a rigorous set of antenatal or fetal conditions which should be excluded from analysis; 'Ultrasound quality control measures', as no study demonstrated a comprehensive quality assurance strategy; and 'Sample size calculation', which was apparent in six studies only. On multiple regression analysis, there was a positive correlation between quality scores and year of publication: quality has improved with time, yet considerable heterogeneity in study methodology is still observed today.Conclusions There is considerable methodological heterogeneity in studies of fetal biometry. Standardisation of methodologies is necessary in order to make correct interpretations and comparisons between different charts. A checklist of recommended methodologies is proposed.

Although intra- and interobserver variability increases with advancing gestation when expressed in millimeters, both are constant as a percentage of the fetal dimensions or when reported as a Z-score. Thus, measurement variability should be considered when interpreting fetal growth rates.

Background Fetal crown-rump length (CRL) measurement by ultrasound in the first trimester is the standard method for pregnancy dating; however, a multitude of CRL equations to estimate gestational age (GA) are reported in the literature.Objective To evaluate the methodological quality used in studies reporting CRL equations to estimate GA using a set of predefined criteria.Search strategy Searches of MEDLINE, EMBASE, and CINAHL databases, from 1948 to 31 January 2011, and secondary reference sources, were performed.Selection criteria Observational ultrasound studies, where the primary aim was to create equations for GA estimation using a CRL measurement.Data collection and analysis Included studies were scored against predefined independently agreed methodological criteria: an overall quality score was calculated for each study.Main results The searches yielded 1142 citations. Two reviewers screened the papers and independently assessed the full-text versions of 29 eligible studies. The highest potential for bias was noted in inclusion and exclusion criteria, and in maternal demographic characteristics. No studies had systematic ultrasound quality-control measures. The four studies with the highest scores (lowest risk of bias) satisfied 18 or more of the 29 criteria; these showed lower variation in GA estimation than the remaining, lower-scoring studies. This was particularly evident at the extremes of GA.Author's conclusions Considerable methodological heterogeneity and limitations exist in studies reporting CRL equations for estimating GA, and these result in a wide range of estimated GAs for any given CRL; however, when studies with the highest methodological quality are used, this range is reduced.

A unified protocol is essential to ensure that fetal ultrasound measurements taken in multicentre research studies are accurate and reproducible. This paper describes the methodology used to take two-dimensional, ultrasound measurements in the longitudinal, fetal growth component of the INTERGROWTH-21 st Project. These standardised methods should minimise the systematic errors associated with pooling data from different study sites. They represent a model for carrying out similar research studies in the future.

Meticulous standardisation and ongoing monitoring of adherence to measurement protocols during data collection are essential to ensure consistency and to minimise systematic error in multicentre studies. Strict ultrasound fetal biometric measurement protocols are used in the st Project so that data of the highest quality from different centres can be compared and potentially pooled. A central Ultrasound Quality Unit (USQU) has been set up to oversee this process. After initial training and standardisation, the USQU monitors the performance of all ultrasonographers involved in the project by continuously assessing the quality of the images and the consistency of the measurements produced. Ultrasonographers are identified when they exceed preset maximum allowable differences. Corrective action is then taken in the form of retraining or simply advice regarding changes in practice. This paper describes the procedures used, which can form a model for research settings involving ultrasound measurements.

BackgroundThe World Health Organization recommends that human growth should be monitored with the use of international standards. However, in obstetric practice, we continue to monitor fetal growth using numerous local charts or equations that are based on different populations for each body structure. Consistent with World Health Organization recommendations, the INTERGROWTH-21st Project has produced the first set of international standards to date pregnancies; to monitor fetal growth, estimated fetal weight, Doppler measures, and brain structures; to measure uterine growth, maternal nutrition, newborn infant size, and body composition; and to assess the postnatal growth of preterm babies. All these standards are based on the same healthy pregnancy cohort. Recognizing the importance of demonstrating that, postnatally, this cohort still adhered to the World Health Organization prescriptive approach, we followed their growth and development to the key milestone of 2 years of age.ObjectiveThe purpose of this study was to determine whether the babies in the INTERGROWTH-21st Project maintained optimal growth and development in childhood.Study DesignIn the Infant Follow-up Study of the INTERGROWTH-21st Project, we evaluated postnatal growth, nutrition, morbidity, and motor development up to 2 years of age in the children who contributed data to the construction of the international fetal growth, newborn infant size and body composition at birth, and preterm postnatal growth standards. Clinical care, feeding practices, anthropometric measures, and assessment of morbidity were standardized across study sites and documented at 1 and 2 years of age. Weight, length, and head circumference age- and sex-specific z-scores and percentiles and motor development milestones were estimated with the use of the World Health Organization Child Growth Standards and World Health Organization milestone distributions, respectively. For the preterm infants, corrected age was used. Variance components analysis was used to estimate the percentage variability among individuals within a study site compared with that among study sites.ResultsThere were 3711 eligible singleton live births; 3042 children (82%) were evaluated at 2 years of age. There were no substantive differences between the included group and the lost-to-follow up group. Infant mortality rate was 3 per 1000; neonatal mortality rate was 1.6 per 1000. At the 2-year visit, the children included in the INTERGROWTH-21st Fetal Growth Standards were at the 49th percentile for length, 50th percentile for head circumference, and 58th percentile for weight of the World Health Organization Child Growth Standards. Similar results were seen for the preterm subgroup that was included in the INTERGROWTH-21st Preterm Postnatal Growth Standards. The cohort overlapped between the 3rd and 97th percentiles of the World Health Organization motor development milestones. We estimated that the variance among study sites explains only 5.5% of the total variability in the length of the children between...

Using a novel method for assessing FV, independent predictors of femoral size were maternal height, adiposity, and serum vitamin D. Future trials should establish whether pregnancy supplementation with vitamin D is beneficial for the fetal skeleton, using FV and PMD as fetal outcome measures.

Objective To assess whether a standardization exercise prior to commencing a fetal growth study involving multiple sonographers can reduce interobserver variation. Methods