Fetal growth standards: individual and global perspectives

Development of Local Birth Weight Reference Based on Gestational Age and Sex in South Kalimantan Province, Indonesia

Purpose

Percentile reference of babies’ birth weight is an effective reference tool for early detection of the risk of neonatal morbidity and impaired growth. However, the lack of minimum local and national perinatal data makes its development in Indonesia difficult. This study aims to develop a local birth weight percentile reference for babies based on gestational age and sex by utilizing local data in South Kalimantan Province which is one of the provinces with the highest neonatal mortality rate in Indonesia.

Patients and Methods

All single live newborns who were born and were recorded in 20 primary healthcare centers, between 1 June 2016 and 30 June 2017, were included in the study. Birth weight percentiles of infants were calculated using the weighted average method. The study focused on neonates born with gestational age from 36 to 40 weeks.

Results

A local birth weight reference for babies has been developed. According to our local reference, the proportion of male newborns with a birth weight < 10th percentile was higher (7.0%) than the existing Indonesian (4.2–4.3%) and international references (3.3–6.2%). Similarly, the proportion of female newborns with a birth weight <10th percentile was higher (6.5%) than the existing Indonesian references (3.6–4.4%) and the global reference (5.8%) but lower than the Intergrowth 21st project (7.2%). The differences suggest that relative birth weight will likely be underestimated (overestimated) if other percentile references are used for the local population.

Conclusion

A local birth weight percentile reference for babies in South Kalimantan Province based on gestational age (36–40 weeks) and sex has been developed. Access to the local data, as baseline information, will allow the compilation and comparison of pregnancy-related outcomes across provinces in Indonesia. Consequently, reliable national perinatal data can be strengthened to establish the national references for newborns’ anthropometric measurements.

The development of an alternative growth chart for estimated fetal weight in the absence of ultrasound: Application in Indonesia

A fetal growth chart is a vital tool for assessing fetal risk during pregnancy. Since fetal weight cannot be directly measured, its reliable estimation at different stages of pregnancy has become an essential issue in obstetrics and gynecology and one of the critical elements in developing a fetal growth chart for estimated fetal weight. In Indonesia, however, a reliable model and data for fetal weight estimation remain challenging, and this causes the absence of a standard fetal growth chart in antenatal care practices. This study has reviewed and evaluated the efficacy of the prediction models used to develop the most prominent growth charts for estimated fetal weight. The study also has discussed the potential challenges when such surveillance tools are utilized in low resource settings. The study, then, has proposed an alternative model based only on maternal fundal height to estimate fetal weight. Finally, the study has developed an alternative growth chart and assessed its capability in detecting abnormal patterns of fetal growth during pregnancy. Prospective data from twenty selected primary health centers in South Kalimantan, Indonesia, were used for the proposed model validation, the comparison task, and the alternative growth chart development using both descriptive and inferential statistics. Results show that limited access to individual fetal biometric characteristics and low-quality data on personal maternal and neonatal characteristics make the existing fetal growth charts less applicable in the local setting. The proposed model based only on maternal fundal height has a comparable ability in predicting fetal weight with less error than the existing models. The results have shown that the developed chart based on the proposed model can effectively detect signs of abnormality, between 20 and 41 weeks, among low birth weight babies in the absence of ultrasound. Consequently, the developed chart would improve the quality of fetal risk assessment during pregnancy and reduce the risk of adverse neonatal outcomes.

Improving the Information Availability and Accessibility of Antenatal Measurements to Ensure Safe Delivery: A Research-Based Policy Recommendation to Reduce Neonatal Mortality in Indonesia

Purpose

Assessing the risks and preventable causes of maternal and neonatal mortality requires the availability of good-quality antenatal information. In Indonesia, however, access to reliable information on pregnancy-related results remains challenging. This research has proposed a research-based policy recommendation to improve availability and accessibility to vital information on antenatal examinations.

Patients and Methods

Descriptive statistics were used to characterize midwives’ capabilities in routinely gathering and recording antenatal information during pregnancy. The investigation was carried out among 19 midwives in South Kalimantan, Indonesia, from April 2016 to October 2017. Antenatal data on 4946 women (retrospective study) and 381 women (prospective study) have been accessed through a scientific and technical training program.

Results

To date, lack of timely access to antenatal information has hampered the process of reducing neonatal mortality in Indonesia. The post-training statistical analysis showed that the training has significantly improved midwives’ scientific knowledge and technical abilities in providing more reliable data on antenatal measurements.

Conclusion

Consistent scientific and technical training among midwives is required to update their knowledge and skills, particularly those relating to documenting the results of antenatal examinations at different stages of pregnancy and using that information to assess potential risks and identify necessary interventions. This should also be followed by routine monitoring on the quality of collected antenatal data. This can be one of the enabling actions to achieve the 2030 Sustainable Development Goals target in reducing neonatal mortality in Indonesia.

The Impact of Scientific and Technical Training on Improving Databases' Adequacy for Fetal Growth Chart Development in Limited-Resource Settings: A Case Study in the Province of South Kalimantan, Indonesia

OBJECTIVES

To assess the impact of scientific and technical training on midwives' abilities in collecting and recording the key performance indicators for fetal growth chart development in limited-resource settings.

METHODS

A descriptive design was used to describe midwives' abilities in timely collecting and recording the minimum data required to estimate fetal weight and develop fetal growth chart. The study was conducted among 19 urban and rural midwives in South Kalimantan, Indonesia, between April 2016 and October 2017. The training provided access to antenatal care information on 4,946 women (retrospective cohort study) and 381 women (prospective cohort study).

RESULTS

The average amount of recorded antenatal care data on the key performance indicators of fetal growth assessment has been significantly improved (from 33.4% to 89.1%, p-value < 0.0005) through scientific and technical training.

CONCLUSIONS

Scientific knowledge and technical abilities have enabled midwives to timely record routine data of the key performance indicators for fetal growth surveillance. Access to this information is vital during different stages of pregnancy. The information can be utilised as evidence-based guidelines to assess fetal risks through fetal weight estimation and to develop fetal growth chart that is currently not available in Indonesian primary healthcare systems.

Foetal weight prediction models at a given gestational age in the absence of ultrasound facilities: application in Indonesia

BACKGROUND

Birth weight is one of the most important indicators of neonatal survival. A reliable estimate of foetal weight at different stages of pregnancy would facilitate intervention plans for medical practitioners to prevent the risk of low birth weight delivery. This study has developed reliable models to more accurately predict estimated foetal weight at a given gestation age in the absence of ultrasound facilities.

METHODS

A primary health care centre was involved in collecting retrospective non-identified Indonesian data. The best subset model selection criteria, coefficient of determination, standard deviation, variance inflation factor, Mallows Cp, and diagnostic tests of residuals were deployed to select the most significant independent variables. Simple and multivariate linear regressions were used to develop the proposed models. The efficacy of models for predicting foetal weight at a given gestational age was assessed using multi-prediction accuracy measures.

RESULTS

Four weight prediction models based on fundal height and its combinations with gestational age (between 32 and 41 weeks) and ultrasonic estimates of foetal head circumference and foetal abdominal circumference have been developed. Multiple comparison criteria show that the proposed models were more accurate than the existing models (mean prediction errors between - 0.2 and 2.4 g and median absolute percentage errors between 4.1 and 4.2%) in predicting foetal weight at a given gestational age (between 35 and 41 weeks).

CONCLUSIONS

This research has developed models to more accurately predict estimated foetal weight at a given gestational age in the absence of ultrasound machines and trained ultra-sonographers. The efficacy of the models was assessed using retrospective data. The results show that the proposed models produced less error than the existing clinical and ultrasonic models. This research has resulted in the development of models where ultrasound facilities do not exist, to predict the estimated foetal weight at varying gestational age. This would promote the development of foetal inter growth charts, which are currently unavailable in Indonesian primary health care systems. Consistent monitoring of foetal growth would alleviate the risk of having inter growth abnormalities, such as low birth weight that is the most leading factor of neonatal mortality.

Individualized growth assessment: conceptual framework and practical implementation for the evaluation of fetal growth and neonatal growth outcome

Fetal growth abnormalities can pose significant consequences on perinatal morbidity and mortality of nonanomalous fetuses. The most widely accepted definition of fetal growth restriction is an estimated fetal weight less than the 10th percentile for gestational age according to population-based criteria. However, these criteria do not account for the growth potential of an individual fetus, nor do they effectively separate constitutionally small fetuses from ones that are malnourished. Furthermore, conventional approaches typically evaluate estimated fetal weight at a single time point, rather than using serial scans, to evaluate growth. This article provides a conceptual framework for the individualized growth assessment of a fetus/neonate based on measuring second-trimester growth velocity of fetal size parameters to estimate growth potential. These estimates specify size models that generate individualized third-trimester size trajectories and predict birth characteristics. Comparisons of measured and predicted values are used to separate normally growing fetuses from those with growth abnormalities. This can be accomplished with individual anatomical parameters or sets of parameters. A practical and freely available software (Individualized Growth Assessment Program) has been developed to allow implementation of this approach for clinical and research purposes.

Indonesian local fetal-weight standard: a better predictive ability for low Apgar score of SGA neonates

Background: Accurate assessment of fetal growth is one of crucial components of antenatal care. A generic reference for fetal-weight and birthweight percentiles that can be easily adapted to local populations have been developed by Mikolajczyk and colleagues. This study aimed to validate our own local percentile standard by evaluating the odds ratio (OR) of low 1st and 5th minute Apgar score for small-for-gestational age (SGA) versus those not SGA.Methods: We used the generic reference tools for fetal-weight and birthweight percentiles developed by Mikolajczyk and colleagues to create our own local standard and then defined the SGA neonates. For validation, we used the database of singleton live deliveries (2,139 birth) during January 1st to December 31st 2013 in Cipto Mangunkusumo Hospital, Jakarta, Indonesia. We compared our reference with that of Hadlock and colleagues. For every reference, the OR of Apgar score <7 at 1st and 5th minutes for infants who were SGA versus those not estimated with bivariate and multivariate analyses.Results: SGA found in 35% (748/2,139) and 13% (278/2,139) of neonates using the definition derived from Indonesian standard and Hadlock’s. OR of Apgar score <7 at 1st and 5th minutes were 3.45 (95% CI=2.56–4.65) and 3.05 (95% CI=1.92–4.83) for the Indonesian local fetal-weight standard compared with respectively 2.14 (95% CI=1.65–2.76) and 1.83 (95% CI=1.21–2.77) for Hadlock and collegues’ reference.Conclusion: Indonesian local fetal-weight standard has a better ability to predict low 1st and 5th minutes Apgar scores of SGA neonates than has the Hadlock and collegues’ reference.

Gestational length assignment based on last menstrual period, first trimester crown-rump length, ovulation, and implantation timing

PURPOSE

Understanding the natural length of human pregnancy is central to clinical care. However, variability in the reference methods to assign gestational age (GA) confound our understanding of pregnancy length. Assignation from ultrasound measurement of fetal crown-rump length (CRL) has superseded that based on last menstrual period (LMP). Our aim was to estimate gestational length based on LMP, ultrasound CRL, and implantation that were known, compared to pregnancy duration assigned by day of ovulation.

METHODS

Prospective study in 143 women trying to conceive. In 71 ongoing pregnancies, gestational length was estimated from LMP, CRL at 10-14 weeks, ovulation, and implantation day. For each method of GA assignment, the distribution in observed gestational length was derived and both agreement and correlation between the methods determined.

RESULTS

Median ovulation and implantation days were 16 and 27, respectively. The gestational length based on LMP, CRL, implantation, and ovulation was similar: 279, 278, 276.5 and 276.5 days, respectively. The distributions for observed gestational length were widest where GA was assigned from CRL and LMP and narrowest when assigned from implantation and ovulation day. The strongest correlation for gestational length assessment was between ovulation and implantation (r = 0.98) and weakest between CRL and LMP (r = 0.88).

CONCLUSIONS

The most accurate method of predicting gestational length is ovulation day, and this agrees closely with implantation day. Prediction of gestational length from CRL and known LMP are both inferior to ovulation and implantation day. This information could have important implications on the routine assignment of gestational age.

Unconditional and conditional standards for fetal abdominal circumference and estimated fetal weight in an ethnic Chinese population: a birth cohort study

BACKGROUND

Diagnosis of intrauterine fetal growth restriction and prediction of small-for-gestation age are often based on fetal abdominal circumference or estimated fetal weight (EFW). The present study aims to create unconditional (cross-sectional) and conditional (longitudinal) standards of fetal abdominal circumference and EFW for use in an ethnic Chinese population.

METHODS

In the Growing Up in Singapore Towards healthy Outcome (GUSTO) birth cohort study in Singapore, fetal biometric measurements were obtained at enrolment to antenatal care (11-12 weeks) and up to three more time points during pregnancy. Singleton pregnancies with a healthy profile defined by maternal, pregnancy and fetal characteristics and birth outcomes were selected for this analysis. The Hadlock algorithm was used to calculate EFW. Mixed effects model was used to establish unconditional and conditional standards in z-scores and percentiles for both genders pooled and for each gender separately.

RESULTS

A total of 313 women were included, of whom 294 had 3 and 19 had 2 ultrasound scans other than the gestational age dating scan. Fetal abdominal circumference showed a roughly linear trajectory from 18 to 36 weeks of gestation, while EFW showed an accelerating trajectory. Gender differences were more pronounced in the 10(th) percentile than the 50(th) or 90(th) percentiles. As compared to other published charts, this population showed growth trajectories that started low but caught up at later gestations.

CONCLUSIONS

Unconditional and conditional standards for monitoring fetal size and fetal growth in terms of abdominal circumference and EFW are available for this ethnic-Chinese population. Electronic spreadsheets are provided for their implementation.

Gestational age and fetal growth assessment among obstetricians

OBJECTIVE

We aimed to characterize gestational age assessment and fetal growth evaluation among obstetricians.

METHODS

Observational, cross-sectional study. We applied a questionnaire to obstetrics specialists and residents, during a national congress on obstetrics.

RESULTS

Almost all 179 respondents correct gestational age in the first trimester by ultrasound, but 63% only if there is a difference of 2-9 days. Ultrasound at 11-13 weeks was considered more accurate than at 8-10 weeks by 81%, with a higher proportion of specialists choosing correctly the last answer (p = 0.05). One-third of the respondents did not correctly point the error associated with the ultrasound estimation of fetal weight (EFW). Of the 88% who use a growth table, only 32% were able to identify it by publication/author. Ninety-eight percent identify fetal growth restriction risk (FGR) with centiles (10th in 76%) and 73% of doctors diagnose FGR without other pathological findings (10th in 49%). 44% finds that a low EFW centile maintenance (4th to 3rd) is more worrisome than the crossing of two quartiles (75th to 24th).

CONCLUSIONS

The role of ultrasound in gestational age assessment and use of EFW use for FGR classification was disparate among participants. EFW and respective centiles may be over relied upon.

Association between reduced stillbirth rates in England and regional uptake of accreditation training in customised fetal growth assessment

OBJECTIVE

To assess the effect that accreditation training in fetal growth surveillance and evidence-based protocols had on stillbirth rates in England and Wales.

DESIGN

Analysis of mortality data from Office of National Statistics.

SETTING

England and Wales, including three National Health Service (NHS) regions (West Midlands, North East and Yorkshire and the Humber) which between 2008 and 2011 implemented training programmes in customised fetal growth assessment.

POPULATION

Live births and stillbirths in England and Wales between 2007 and 2012.

MAIN OUTCOME MEASURE

Stillbirth.

RESULTS

There was a significant downward trend (p=0.03) in stillbirth rates between 2007 and 2012 in England to 4.81/1000, the lowest rate recorded since adoption of the current stillbirth definition in 1992. This drop was due to downward trends in each of the three English regions with high uptake of accreditation training, and led in turn to the lowest stillbirth rates on record in each of these regions. In contrast, there was no significant change in stillbirth rates in the remaining English regions and Wales, where uptake of training had been low. The three regions responsible for the record drop in national stillbirth rates made up less than a quarter (24.7%) of all births in England. The fall in stillbirth rate was most pronounced in the West Midlands, which had the most intensive training programme, from the preceding average baseline of 5.73/1000 in 2000-2007 to 4.47/1000 in 2012, a 22% drop which is equivalent to 92 fewer deaths a year. Extrapolated to the whole of the UK, this would amount to over 1000 fewer stillbirths each year.

CONCLUSIONS

A training and accreditation programme in customised fetal growth assessment with evidence-based protocols was associated with a reduction in stillbirths in high-uptake areas and resulted in a national drop in stillbirth rates to their lowest level in 20 years.

Impact of ovulation and implantation timing on first-trimester crown-rump length and gestational age

OBJECTIVE

To determine the impact of ovulation and implantation timing on first-trimester crown-rump length (CRL) and the derived gestational age (GA).

METHOD

One hundred and forty-three women who were trying to conceive were recruited prospectively. The timing of ovulation and implantation and the ovulation to implantation (O-I) interval were established in 101 pregnancies using home urinary tests for luteinizing hormone and human chorionic gonadotropin. In 71 ongoing pregnancies, GA determined by measurement of fetal CRL at 10-14 weeks' gestation was compared with GA based on ovulation and implantation day. First-trimester growth was determined by serial ultrasound scans at 6-7, 8-9 and 10-14 weeks.

RESULTS

The median ovulation and implantation days were 16 and 27, respectively, with an O-I interval of 11 days. GA estimated from CRL at 10-14 weeks was on average 1.3 days greater than that derived from ovulation timing. CRL Z-score was inversely related to O-I interval (ρ= -0.431, P=0.0009). There was no significant relationship between CRL growth rate and the difference between observed CRL and expected CRL based on GA from last menstrual period (ρ=0.224, P=0.08).

CONCLUSIONS

Early implantation leads to a larger CRL and late implantation to a smaller CRL at 10-14 weeks, independent of CRL growth rate. Implantation timing is a major determinant of fetal size at 10-14 weeks and largely explains the variation in estimates of GA in the first trimester derived from embryonic or fetal CRL.

Body weight, length and head circumference at birth in a cohort of Turkish newborns

OBJECTIVE

Intrauterine growth references are primarily useful indicators in the assessment of the general health status of newborn infants. Although Lubchenco's references are still used in many neonatal care units, we believe that there is a need for up-to-date intrauterine growth references specific for different populations. To develop gestational age-and gender-specific national references for birth weight, birth length and head circumference.

METHODS

Data were collected from neonatal records of perinatology services of eleven hospitals from January to December 2009. The anthropometry of a total of 4750 singleton live births born between 28 and 41 weeks of gestation were recorded. Means and standard deviations were calculated, and percentiles for each gender and gestational week were produced using the LMS program. The results were compared with US infants and also with local data.

RESULTS

Gestational age- and gender-specific 3rd, 5th, 10th, 15th, 25th, 50th, 75th, 85th, 90th, 95th and 97th percentile values were produced. Comparison of the 10th, 50th and 90th percentile values showed that the boys were heavier and longer than the girls. Head circumference values were also higher in the boys. Proportions of small for gestational age (SGA), appropriate for gestational age (AGA) and large for gestational age (LGA) infants in the sample were 10.1%, 79.1% and 10.8%, respectively.

CONCLUSION

These gender- and gestational age-specific references will be of use in clinical practice and also for research purposes until more comprehensive, reliable and accessible national data pertaining to the intrauterine growth of Turkish infants are produced.

Catch up growth in low birth weight infants: striking a healthy balance

Catch-up growth in the first few months of life is seen almost ubiquitously in infants born small for their gestational age and conventionally considered highly desirable as it erases the growth deficit. However, recently such growth has been linked to an increased risk of later adiposity, insulin resistance and cardiovascular disease in both low income and high-income countries. In India, a third of all babies are born with a low birth weight, but the optimal growth pattern for such infants is uncertain. As a response to the high rates of infectious morbidities, undernutrition and stunting in children, the current policy is to promote rapid growth in infancy. However, with socio-economic transition and urbanization making the Indian environment more obesogenic, and the increasing prevalence of type 2 diabetes and cardiovascular disease, affecting progressively younger population, the long term adverse programming effect of fast/excessive weight gain in infancy on later body composition and metabolism may outweigh short-term benefits. This review discusses the above issues focusing on the need to strike a healthy balance between the risks and benefits of catch-up growth in Indian infants.