Customized large-for-gestational-age birthweight at term and the association with adverse perinatal outcomes

Association between excessive fetal growth and maternal cancer in Shanghai, China: a large, population-based cohort study

The prevalence of high birth weight or large for gestational age (LGA) infants is increasing, with increasing evidence of pregnancy-related factors that may have long-term impacts on the health of the mother and baby. We aimed to determine the association between excessive fetal growth, specifically LGA and macrosomia, and subsequent maternal cancer by performing a prospective population-based cohort study. The data set was based on the Shanghai Birth Registry and Shanghai Cancer Registry, with medical records from the Shanghai Health Information Network as a supplement. Macrosomia and LGA prevalence was higher in women who developed cancer than in women who did not. Having an LGA child in the first delivery was associated with a subsequently increased risk of maternal cancer (hazard ratio [HR] = 1.08, 95% confidence interval [CI] 1.04-1.11). Additionally, in the last and heaviest deliveries, there were similar associations between LGA births and maternal cancer rates (HR = 1.08, 95% CI 1.04-1.12; HR = 1.08, 95% CI 1.05-1.12, respectively). Furthermore, a substantially increased trend in the risk of maternal cancer was associated with birth weights exceeding 2500 g. Our study supports the association between LGA births and increased risks of maternal cancer, but this risk requires further investigation.

[Review of the literature on intrauterine and birthweight charts]

OBJECTIVES

To describe the main intrauterine and birthweight charts and review the studies comparing their performance for the identification of infants at risk of adverse perinatal outcomes.

METHODS

We carried out a literature search using Medline and selected the charts most frequently cited in the literature, French charts and those recently published.

RESULTS

Current knowledge on the association between mortality and morbidity and growth anomalies (small and large for gestational age) mostly relies on the use of descriptive charts which describe the weight distribution in unselected populations. Prescriptive charts, which describe ideal growth in low risk populations, have been constructed more recently. Few studies have evaluated whether the thresholds used to identify infants at risk with descriptive charts (such as the 3^rd or the 10^th percentile) are applicable to prescriptive charts. There is a large variability in the percentage of fetuses or newborns identified as being at risk by each chart, with from 3 to 25% having with a weight under the 10^th percentile, regardless of whether descriptive or prescriptive charts are used. The sensitivity and specificity of antenatal screening for small or large for gestational age newborns depends on the chart used to derive estimated fetal weight percentiles.

CONCLUSION

There is marked variability between intrauterine growth charts that can influence the percentage of infants identified as having abnormal growth. These results show that before the adoption of a growth chart, it is essential to evaluate whether it adequately describes the population and its performance for identifying of infants at risk because of growth anomalies.

A new method for customized fetal growth reference percentiles

BACKGROUND

Customized fetal growth charts assume birthweight at term to be normally distributed across the population with a constant coefficient of variation at earlier gestational ages. Thus, standard deviation used for computing percentiles (e.g., 10th, 90th) is assumed to be proportional to the customized mean, although this assumption has never been formally tested.

METHODS

In a secondary analysis of NICHD Fetal Growth Studies-Singletons (12 U.S. sites, 2009-2013) using longitudinal sonographic biometric data (n = 2288 pregnancies), we investigated the assumptions of normality and constant coefficient of variation by examining behavior of the mean and standard deviation, computed following the Gardosi method. We then created a more flexible model that customizes both mean and standard deviation using heteroscedastic regression and calculated customized percentiles directly using quantile regression, with an application in a separate study of 102, 012 deliveries, 37-41 weeks.

RESULTS

Analysis of term optimal birthweight challenged assumptions of proportionality and that values were normally distributed: at different mean birthweight values, standard deviation did not change linearly with mean birthweight and the percentile computed with the normality assumption deviated from empirical percentiles. Composite neonatal morbidity and mortality rates in relation to birthweight < 10th were higher for heteroscedastic and quantile models (10.3% and 10.0%, respectively) than the Gardosi model (7.2%), although prediction performance was similar among all three (c-statistic 0.52-0.53).

CONCLUSIONS

Our findings question normality and constant coefficient of variation assumptions of the Gardosi customization method. A heteroscedastic model captures unstable variance in customization characteristics which may improve detection of abnormal growth percentiles.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00912132.

Induction of labour for predicted macrosomia: study protocol for the 'Big Baby' randomised controlled trial

INTRODUCTION

Large-for-gestational age (LGA) fetuses have an increased risk of shoulder dystocia. This can lead to adverse neonatal outcomes and death. Early induction of labour in women with a fetus suspected to be macrosomic may mitigate the risk of shoulder dystocia. The Big Baby Trial aims to find if induction of labour at 38⁺⁰-38⁺⁴ weeks' gestation, in pregnancies with suspected LGA fetuses, reduces the incidence of shoulder dystocia.

METHODS AND ANALYSIS

The Big Baby Trial is a multicentre, prospective, individually randomised controlled trial of induction of labour at 38⁺⁰ to 38⁺⁴ weeks' gestation vs standard care as per each hospital trust (median gestation of delivery 39⁺⁴) among women whose fetuses have an estimated fetal weight >90th customised centile according to ultrasound scan at 35⁺⁰ to 38⁺⁰ weeks' gestation. There is a parallel cohort study for women who decline randomisation because they opt for induction, expectant management or caesarean section. Up to 4000 women will be recruited and randomised to induction of labour or to standard care. The primary outcome is the incidence of shoulder dystocia; assessed by an independent expert group, blind to treatment allocation, from delivery records. Secondary outcomes include birth trauma, fractures, haemorrhage, caesarean section rate and length of inpatient stay. The main trial is ongoing, following an internal pilot study. A qualitative reporting, health economic evaluation and parallel process evaluation are included.

ETHICS AND DISSEMINATION

The study received a favourable opinion from the South West-Cornwall and Plymouth Health Research Authority on 23/03/2018 (IRAS project ID 229163). Study results will be reported in the National Institute for Health Research journal library and published in an open access peer-reviewed journal. We will plan dissemination events for key stakeholders.

TRIAL REGISTRATION NUMBER

ISRCTN18229892.

[Ante- and postnatal growth charts in France - guidelines for clinical practice from the Collège national des gynécologues et obstétriciens français (CNGOF) and from the Société française de néonatologie (SFN)]

OBJECTIVE

To recommend the most appropriate biometric charts for the detection of antenatal growth abnormalities and postnatal growth surveillance.

METHODS

Elaboration of specific questions and selection of experts by the organizing committee to answer these questions; analysis of the literature by experts and drafting conclusions by assigning a recommendation (strong or weak) and a quality of evidence (high, moderate, low, very low) and for each question; all these recommendations have been subject to multidisciplinary external review (obstetrician gynecologists, pediatricians). The objective for the reviewers was to verify the completeness of the literature review, to verify the levels of evidence established and the consistency and applicability of the resulting recommendations. The overall review of the literature, quality of evidence and recommendations were revised to take into consideration comments from external reviewers.

RESULTS

Antenatally, it is recommended to use all WHO fetal growth charts for EFW and common ultrasound biometric measurements (strong recommendation; low quality of evidence). Indeed, in comparison with other prescriptive curves and descriptive curves, the WHO prescriptive charts show better performance for the screening of SGA (Small for Gestational Age) and LGA (Large for Gestational Age) with adequate proportions of fetuses screened at extreme percentiles in the French population. It also has the advantages of having EFW charts by sex and biometric parameters obtained from the same perspective cohort of women screened by qualified sonographers who measured the biometric parameters according to international standards. Postnatally, it is recommended to use the updated Fenton charts for the assessment of birth measurements and for growth monitoring in preterm infants (strong recommendation; moderate quality of evidence) and for the assessment of birth measurements in term newborn (expert opinion).

CONCLUSION

It is recommended to use WHO fetal growth charts for antenatal growth monitoring and Fenton charts for the newborn.

Neurodevelopmental outcomes of singleton large for gestational age infants <29 weeks' gestation: a retrospective cohort study

OBJECTIVE

To compare neurodevelopmental outcomes of large and appropriate for gestational age (LGA, AGA) infants <29 weeks' gestation at 18-24 months of corrected age.

STUDY DESIGN

Retrospective cohort study using the Canadian Neonatal Network and Canadian Neonatal Follow-Up Network databases. Primary outcome was a composite of death or significant neurodevelopmental impairment (NDI), defined as severe cerebral palsy, Bayley III cognitive, language and motor scores of <70, need for hearing aids or cochlear implant and bilateral visual impairment. Univariate and multivariable logistic analyses were applied for outcomes.

RESULTS

The study cohort comprised 170 LGA and 1738 AGA infants. There was no difference in significant NDI or individual components of the Bayley III between LGA and AGA groups. LGA was associated with the increased risk of death by follow-up, 44/170 (25.9%) vs. 320/1738 (18.4%) (aOR: 1.60 95% CI: 1.00-2.54).

CONCLUSIONS

Risk of NDI was similar between LGA and AGA infants.

Fetal Growth Acceleration-Current Approach to the Big Baby Issue

Background and Objectives: Fetal overgrowth is related to many perinatal complications, including stillbirth, cesarean section, maternal and neonatal injuries, and shoulder dystocia. It is related to maternal diabetes, obesity, and gestational weight gain but also happens in low-risk pregnancies. There is ongoing discussion regarding definitions, methods of detection, and classification. The method used for detection is crucial as it draws a line between those at risk and low-risk popula-tions. Materials and Methods: For this narrative review, relevant evidence was identified through PubMed search with one of the general terms (macrosomia, large-for-gestational-age) combined with the outcome of interest. Results: This review summarizes evidence on the relation of fetal overgrowth with stillbirth, cesarean sections, shoulder dystocia, anal sphincter injury, and hem-orrhage. Customized growth charts help to detect mothers and fetuses at risk of those complica-tions. Relations between fetal overgrowth and diabetes, maternal weight, and gestational weight gain were investigated. Conclusions: a substantial proportion of complications are an effect of the fetus growing above its potential and should be recognized as a new dangerous condition of Fetal Growth Acceleration.

Large-for-gestational-age or macrosomia as a classifier for risk of adverse perinatal outcome: a retrospective cross-sectional study

OBJECTIVE

Small for gestational age (SGA) fetuses and neonates are of great interest, while those who are too big are much less studied. The aim was to analyze the classifiers described by ACOG "Fetal macrosomia" practice bulletin as predictors of adverse perinatal outcomes for overgrown fetuses and their mothers.

MATERIALS

From a database of 53,586 singleton term births, appropriate-for-gestational-age (AGA), large for gestational age (LGA), and macrosomic deliveries were selected. AGA served as a control. The crude and adjusted odds ratios (aORs) were calculated for large-for-gestational-age >90th centile, and macrosomia >4000 g, >4250 g, and >4500 g. Patients with and without diabetes were analyzed separately.

RESULTS

Macrosomia >4000 g performed poorer than other classifiers. LGA performed comparably to other definitions of macrosomia. Diabetes carries a severe risk of complications for overgrown neonates, but those non-diabetic also have increased risk.

CONCLUSIONS

Definition of macrosomia as weight >4000 g should be reconsidered. LGA >90th centile should be used as a definition of fetal overgrowth along with other definitions of macrosomia.

Development of birth weight for gestational age charts and comparison with currently used charts: defining growth in the Polish population

OBJECTIVES

This study aimed to obtain the reference curves of birth weight for gestational age percentiles for the Polish population and to compare them to published charts in terms of detected proportions of small for gestational age (SGA) and large for gestational age (LGA).

METHODS

The reference curves of birth weight from 24 to 42 weeks of gestation were computed based on 39,092 singleton deliveries. The nomograms included the 3rd to the 97th percentiles and standard deviations. The percentiles were calculated for female and male newborns. The theoretical and true proportions of percentiles for the studied population were estimated based on six growth charts (Fenton, Intergrowth Project, global reference chart, Yudkin, Dubiel, and the World Health Organization chart).

RESULTS

The 50th percentile male and female newborns at 40 weeks weighed 3645.8 and 3486.7 g, respectively. The difference was 159.1 g. The ranges between the 3rd and 97th percentile at 40 weeks were 1481.5 g for males and 1423.5 for females. A total of 9.8% SGA and 10.27% LGA were defined, higher than that identified using the Fenton chart and even higher than that identified using the Intergrowth Project.

CONCLUSION

Population growth charts identify more newborns with abnormal growth (both LGA and SGA). The similarity between charts in LGA above the 95th percentile is observed. The discrepancies in SGA are significantly greater, specifically in preterm births than in term births. Similar coverage is found in term pregnancies, regardless of birth weight for gestational age or intrauterine charts. The feasibility of a Polish population growth chart needs to be validated for predicting adverse perinatal outcomes.

Determination of birth-weight centile thresholds associated with adverse perinatal outcomes using population, customised, and Intergrowth charts: A Swedish population-based cohort study

BACKGROUND

Although many studies have compared birth-weight charts to determine which better identify infants at risk of adverse perinatal outcomes, less attention has been given to the threshold used to define small or large for gestational age (SGA or LGA) infants. Our aim was to explore different thresholds associated with increased risk of adverse perinatal outcomes using population, customised, and Intergrowth centile charts.

METHODS AND FINDINGS

This is a population-based cohort study (Swedish Medical Birth Registry), which included term singleton births between 2006 and 2015 from women with available data on first-trimester screening. Population, customised, and Intergrowth charts were studied. Outcomes included cesarean section, postpartum haemorrhage, severe perineal tear, Apgar score at 5 minutes, neonatal morbidity, and perinatal mortality. Odds for each outcome were assessed in intervals of 5 centiles of birth weight (reference being 40th-60th centiles) using logistic regression. Intervals of 5% of the population were also explored. Sensitivity for fixed false-positive rates (FPRs) was reported for neonatal outcomes. Data from 212,101 births were analysed. Mean age was 33 ± 5 years, 48% of women were nulliparous, and 80% were born in Sweden. Prevalence of SGA (<10th centile) was 10.1%, 10.0%, and 3.1%, and prevalence of LGA (>90th centile) was 10.0%, 8.2%, and 25.1%, assessed using population, customised, and Intergrowth charts, respectively. In small infants, the risk of perinatal mortality was consistently increased below the 15th, 10th, and 35th birth-weight centiles for the respective charts (odds ratio [OR] 1.59, 95% confidence interval [CI] 1.05-2.39, p = 0.03 for 10th-15th population centile; OR 2.54, 95% CI 1.74-3.71, p < 0.001 for 5th-10th customised centile; OR 1.81, 95% CI 1.07-3.04, p = 0.03 for 30th-35th Intergrowth centile). The strength of association with adverse perinatal outcomes was different between infants below the 5th birth-weight centile for each chart (OR 4.47, 95% CI 3.30-6.04, p < 0.001 for the population chart; OR 5.78, 95% CI 4.22-7.91, p < 0.001 for the customised chart; OR 10.74, 95% CI 7.32-15.77, p < 0.001 for the Intergrowth chart) but similar in the smallest 5% of the population (OR 4.34, 95% CI 3.22-5.86, p < 0.001 for the population chart; OR 5.23, 95% CI 3.85-7.11, p < 0.001 for the customised chart; OR 4.69, 95% CI 3.47-6.34, p < 0.001 for the Intergrowth chart). For a fixed FPR of 10%, different thresholds for each chart achieved similar sensitivity for perinatal mortality in small infants (29% for all charts). Similar behaviour of different thresholds and similar risk/sensitivity for fixed FPR were observed in relation to other outcomes and for LGA infants. Limitations of this study include the relative homogeneity of the Swedish population, which limits generalisability to other populations; customised centiles may perform differently in populations with increased heterogeneity of ethnic background.

CONCLUSIONS

The risk of adverse outcomes was consistent across proportions of the population but did not reflect fixed thresholds, such as the 10th or 90th centiles, across different growth charts. Chart-specific thresholds for the population should be considered in clinical practice.

Effect of maternal age, height, BMI and ethnicity on birth weight: an Italian multicenter study

AIM

To assess the effect of maternal age, height, early pregnancy body mass index (BMI) and ethnicity on birth weight.

SUBJECTS AND METHODS

A cross-sectional study was conducted on more than 42,000 newborns. Ethnicity was defined by maternal country of birth or, when missing (<0.6% of records), by citizenship. The effect of maternal characteristics on birth weight was evaluated with general linear models.

RESULTS

Maternal height and BMI, although not age, significantly affected birth weight. Among Italian babies, 4.7% of newborns were classified as appropriate-for-gestational age (AGA) (birth weight between the 10th and the 90th centile) according to the country-specific Italian Neonatal Study (INeS) charts and were re-classified as either large-(LGA) (birth weight >90th centile) or small-(SGA) (birth weight <10th centile) for gestational age (GA) after adjustment for maternal characteristics. On the contrary, 1.6% of Italian newborns were classified as SGA or LGA according to the INeS charts and re-classified as AGA after adjustment. Maternal ethnicity had a significant impact on birth weight. Specifically, babies born to Senegalese mothers were the lightest, whilst babies born to Chinese mothers were the heaviest.

CONCLUSIONS

Maternal height and early pregnancy BMI, should be considered in the evaluation of birth weight. The effect of ethnicity suggests the appropriateness of ethnic-specific charts. Further studies are necessary to determine if changes in birth weight classification, may translate into improved detection of subjects at risk of adverse outcomes.

Outcomes for the First Year of Ontario's Birth Center Demonstration Project

INTRODUCTION

In 2014, Ontario opened 2 stand-alone midwifery-led birth centers. Using mixed methods, we evaluated the first year of operations for quality and safety, client experience, and integration into the maternity care community. This article reports on our study of safety and quality of care.

METHODS

This descriptive evaluation focused on women admitted to a birth center at the beginning of labor. For context, we matched this cohort (on a 1:4 basis) with similar low-risk midwifery clients giving birth in a hospital. Data sources included Ontario's Better Outcomes Registry and Network (BORN) Information System, the Canadian Institute for Health Information, Ontario census data, and birth center records.

RESULTS

Of 495 women admitted to a birth center, 87.9% experienced a spontaneous vaginal birth, regardless of the eventual location of birth, and 7.7% had a cesarean birth. The transport rate to a hospital was 26.3%. When compared with midwifery clients with a planned hospital birth, rates of intervention (epidural analgesia, labor augmentation, assisted vaginal birth, and cesarean birth) were significantly lower in the planned birth center group, even when controlled for previous cesarean birth and body mass index. Markers of potential morbidity were identified in about 10% of birth center births; however, there were no short-term health impacts up to discharge from midwifery care at 6 weeks postpartum. Care was low in intervention and safe (minimal negative outcomes and transport rates comparable to the literature).

DISCUSSION

In the first year of operation, care was consistent with national guidelines, and morbidity and mortality rates and intervention rates were low for women with low-risk pregnancies seeking a low-intervention approach for labor and birth. Further evaluation to confirm these findings is required as the number of births grows.

Perinatal Risk Factors and ADHD in Children and Adolescents: A Hierarchical Structure of Disorder Predictors

OBJECTIVE

The aim of the study was to hierarchically assess the predictive power of low and high birth weight, pre-term and post-term birth, and low Apgar score as the risk factors for ADHD.

METHOD

The data of 132 boys diagnosed with ADHD and 146 boys from control group, aged 6 to 18 years, have been analyzed. The boys were categorized according to term of birth, birth weight, and Apgar score. CART method (Classification and Regression Trees) was used for assessment of the relationship between perinatal factors and the risk of ADHD.

RESULTS

Low Apgar score (21.97% vs. 13.01%) and post-term birth (12.12% vs. 0.68%) were more frequent in the sample than in the control group. CART method additionally indicated low birth weight as associated with the risk of ADHD. Among analyzed risk factors, Apgar score had the highest predictive value.

CONCLUSION

The decreased Apgar score is the most important perinatal risk factor of ADHD. Research results also indicated a high significance of post-term birth in predicting the disorder.

Antenatal risk factors associated with neonatal morbidity in large-for-gestational-age infants: an international prospective cohort study

INTRODUCTION

Large-for-gestational-age infants are associated with increased risk of neonatal morbidity and mortality. However, most of them will not have adverse outcomes. Our aim was to identify antenatal clinical factors associated with neonatal morbidity in large-for-gestational-age infants.

MATERIAL AND METHODS

Nulliparous women from the Screening for Pregnancy Endpoints (SCOPE) study were included. We compared maternal and fetal factors between large-for-gestational-age infants (birthweight >90th customized centile) with and without neonatal morbidity, defined as admission to a neonatal intensive care unit or severe neonatal morbidity. Factors were selected based on a priori hypotheses of association and included maternal demography, anthropometric measures and self-reported physical activity (15 and 20 weeks), fetal biometry (20 weeks), and clinical information. Multivariable logistic regression was used to identify risk factors. Stratified analyses were performed by maternal obesity and physical activity.

RESULTS

Among term pregnancies, prevalence of large-for-gestational-age infants was 9.3% (491/5255), with 11.8% (58/491) prevalence of neonatal morbidity. Random glucose at 20 weeks (odds ratio 1.52; 95% confidence interval 1.17-1.97, per 1 mmol/L increase) and no regular physical activity at 20 weeks (odds ratio 3.93; 95% confidence interval 1.75-8.83) were associated with increased risk of neonatal morbidity after adjustment for birthweight, gestational age at delivery and gestational diabetes. The increased risk associated with higher glucose levels was not evident in women with regular physical activity or without obesity.

CONCLUSIONS

Regular physical activity in mid-pregnancy is associated with lower risk for neonatal morbidity in large-for-gestational-age infants and seems to offer protection against the increased risk associated with higher maternal glucose levels.

Determinants of early neonatal mortality in Afghanistan: an analysis of the Demographic and Health Survey 2015

Background

Neonatal mortality is declining slowly compared to under-five mortality in many developing countries including Afghanistan. About three-fourths of these deaths occur in the early neonatal period (i.e., the first week of life). Although a number of studies investigated determinants of early neonatal mortality in other countries, there is a lack of evidence regarding this in Afghanistan. This study investigated determinants of early neonatal mortality in Afghanistan.

Methods

Data from the Afghanistan Demographic and Health Survey 2015 (AfDHS 2015) were analyzed. After reporting the weighted frequency distributions of selected factors, a multilevel logistic regression model revealed adjusted associations of factors with early neonatal mortality.

Results

A total of 19,801 weighted live-births were included in our analysis; 266 (1.4%) of the newborns died in this period. Multivariable analysis found that multiple gestations (adjusted odds ratio (AOR): 9.3; 95% confidence interval (CI): 5.7–15.0), larger (AOR: 2.9; 95% CI: 2.2–3.8) and smaller (AOR: 1.8; 95% CI: 1.2–2.6) than average birth size, maternal age ≤ 18 years (AOR: 1.8; 95% CI: 1.1–3.2) and ≥ 35 years (AOR: 1.7; 95% CI: 1.3–2.3), and birth interval of < 2 years (AOR: 2.6; 95% CI: 1.4–4.9) had higher odds of early neonatal mortality. On the other hand, antenatal care by a skilled provider (AOR: 0.7; 95% CI: 0.5–0.9), facility delivery (AOR: 0.7; 955 CI: 0.5–0.9), paternal higher education level (AOR: 0.7; 95% CI: 0.5–1.0), living in north-western (AOR: 0.3; 95% CI: 0.1–0.6), central-western regions (AOR: 0.5; 95% CI: 0.3–0.9) and in a community with higher maternal education level (AOR: 0.4; 95% CI: 0.2–0.9) had negative association.

Conclusions

Several individual, maternal and community level factors influence early neonatal deaths in Afghanistan; significance of the elements of multiple levels indicates that neonatal survival programs should follow a multifaceted approach to incorporate these associated factors. Programs should focus on birth interval prolongation with the promotion of family planning services, utilization of antenatal care and institutional delivery services along with management of preterm and sick infants to prevent this large number of deaths in this period.

Impact of gestational weight gain and prepregnancy body mass index on the prevalence of large-for-gestational age infants in two cohorts of women with type 1 insulin-dependent diabetes: a cross-sectional population study

OBJECTIVES

Despite improvements in treatment modalities, large-for-gestational age (LGA) prevalence has remained between 30% and 40% among infants of mothers with type 1 insulin-dependent diabetes mellitus (TIDM). Our objective was to estimate LGA prevalence and examine the association between gestational weight gain (GWG) and prepregnancy body mass index (BMI) with LGA among mothers with TIDM.

DESIGN

Cross-sectional study.

SETTING

Regional data in Cincinnati, Ohio, from the Diabetes in Pregnancy Program Project (PPG), a prospective cohort for the period 1978-1993; national data from Consortium on Safe Labor (CSL), a multicentre cross-sectional study for the period 2002-2008.

PARTICIPANTS

The study included 333 pregnancies in the PPG and 358 pregnancies in the CSL. Pregnancies delivered prior to 23 weeks' gestation were excluded. Women with TIDM in the PPG were identified according to physician confirmation of ketoacidosis, and/or c-peptide levels, and by International Classification of Diseases, ninth version codes within the CSL. LGA was identified as birth weight >90th percentile according to gestational age, race and sex.

MAIN OUTCOME MEASURES

LGA at birth.

RESULTS

Mean±SD maternal age at delivery was 26.4±5.1 years for PPG women and 27.5±6.0 years for CSL women, p=0.008. LGA prevalence did not significantly differ between cohorts (PPG: 40.2% vs CSL: 36.6%, p=0.32). More women began pregnancy as overweight in the later cohort (PPG (16.8%) vs CSL (27.1%), p<0.001). GWG exceeding Institute of Medicine (IOM) guidelines was higher in the later CSL (56.2%) vs PPG (42.3%) cohort, p<0.001. Normal-weight women with GWG within IOM guidelines had a lower LGA prevalence in CSL (PPG: 30.6% vs CSL: 13.7%), p=0.001.

CONCLUSIONS

Normal-weight women with GWG within IOM guidelines experienced a lower LGA prevalence, supporting the importance of adherence to IOM guidelines for GWG to reduce LGA. High BMI and GWG may be hindering a reduction in LGA prevalence.

Customized growth charts: rationale, validation and clinical benefits

Appropriate standards for the assessment of fetal growth and birthweight are central to good clinical care, and have become even more important with increasing evidence that growth-related adverse outcomes are potentially avoidable. Standards need to be evidence based and validated against pregnancy outcome and able to demonstrate utility and effectiveness. A review of proposals by the Intergrowth consortium to adopt their single international standard finds little support for the claim that the cases that it identifies as small are due to malnutrition or stunting, and substantial evidence that there is normal physiologic variation between different countries and ethnic groups. It is possible that the one-size-fits-all standard ends up fitting no one and could be harmful if implemented. An alternative is the concept of country-specific charts that can improve the association between abnormal growth and adverse outcome. However, such standards ignore individual physiologic variation that affects fetal growth, which exists in any heterogeneous population and exceeds intercountry differences. It is therefore more logical to adjust for the characteristics of each mother, taking her ethnic origin and her height, weight, and parity into account, and to set a growth and birthweight standard for each pregnancy against which actual growth can be assessed. A customized standard better reflects adverse pregnancy outcome at both ends of the fetal size spectrum and has increased clinicians' confidence in growth assessment, while providing reassurance when abnormal size merely represents physiologic variation. Rollout in the United Kingdom has proceeded as part of the comprehensive Growth Assessment Protocol (GAP), and has resulted in a steady increase in antenatal detection of babies who are at risk because of fetal growth restriction. This in turn has been accompanied by a year-on-year drop in stillbirth rates to their lowest ever levels in England. A global version of customized growth charts with over 100 ethnic origin categories is being launched in 2018, and will provide an individualized, yet universally applicable, standard for fetal growth.

A new customized fetal growth standard for African American women: the PRB/NICHD Detroit study

BACKGROUND

The assessment of fetal growth disorders requires a standard. Current nomograms for the assessment of fetal growth in African American women have been derived either from neonatal (rather than fetal) biometry data or have not been customized for maternal ethnicity, weight, height, and parity and fetal sex.

OBJECTIVE

We sought to (1) develop a new customized fetal growth standard for African American mothers; and (2) compare such a standard to 3 existing standards for the classification of fetuses as small (SGA) or large (LGA) for gestational age.

STUDY DESIGN

A retrospective cohort study included 4183 women (4001 African American and 182 Caucasian) from the Detroit metropolitan area who underwent ultrasound examinations between 14-40 weeks of gestation (the median number of scans per pregnancy was 5, interquartile range 3-7) and for whom relevant covariate data were available. Longitudinal quantile regression was used to build models defining the "normal" estimated fetal weight (EFW) centiles for gestational age in African American women, adjusted for maternal height, weight, and parity and fetal sex, and excluding pathologic factors with a significant effect on fetal weight. The resulting Perinatology Research Branch/Eunice Kennedy Shriver National Institute of Child Health and Human Development (hereinafter, PRB/NICHD) growth standard was compared to 3 other existing standards--the customized gestation-related optimal weight (GROW) standard; the Eunice Kennedy Shriver National Institute of Child Health and Human Development (hereinafter, NICHD) African American standard; and the multinational World Health Organization (WHO) standard--utilized to screen fetuses for SGA (<10th centile) or LGA (>90th centile) based on the last available ultrasound examination for each pregnancy.

RESULTS

First, the mean birthweight at 40 weeks was 133 g higher for neonates born to Caucasian than to African American mothers and 150 g higher for male than female neonates; maternal weight, height, and parity had a positive effect on birthweight. Second, analysis of longitudinal EFW revealed the following features of fetal growth: (1) all weight centiles were about 2% higher for male than for female fetuses; (2) maternal height had a positive effect on EFW, with larger fetuses being affected more (2% increase in the 95th centile of weight for each 10-cm increase in height); and (3) maternal weight and parity had a positive effect on EFW that increased with gestation and varied among the weight centiles. Third, the screen-positive rate for SGA was 7.2% for the NICHD African American standard, 12.3% for the GROW standard, 13% for the WHO standard customized by fetal sex, and 14.4% for the PRB/NICHD customized standard. For all standards, the screen-positive rate for SGA was at least 2-fold higher among fetuses delivered preterm than at term. Fourth, the screen-positive rate for LGA was 8.7% for the GROW standard, 9.2% for the PRB/NICHD customized standard, 10.8% for the WHO standard customized by fetal sex, and 12.3% for the NICHD African American standard. Finally, the highest overall agreement among standards was between the GROW and PRB/NICHD customized standards (Cohen's interrater agreement, kappa = 0.85).

CONCLUSION

We developed a novel customized PRB/NICHD fetal growth standard from fetal data in an African American population without assuming proportionality of the effects of covariates, and without assuming that these effects are equal on all centiles of weight; we also provide an easy-to-use centile calculator. This standard classified more fetuses as being at risk for SGA compared to existing standards, especially among fetuses delivered preterm, but classified about the same number of LGA. The comparison among the 4 growth standards also revealed that the most important factor determining agreement among standards is whether they account for the same factors known to affect fetal growth.

Customized vs population-based growth charts to identify neonates at risk of adverse outcome: systematic review and Bayesian meta-analysis of observational studies

OBJECTIVE

To compare the effectiveness of customized vs population-based growth charts for the prediction of adverse pregnancy outcomes.

METHODS

MEDLINE, ClinicalTrials.gov and The Cochrane Library were searched up to 31 May 2016 to identify interventional and observational studies comparing adverse outcomes among large- (LGA) and small- (SGA) for-gestational-age neonates, when classified according to customized vs population-based growth charts. Perinatal mortality and admission to the neonatal intensive care unit (NICU) of both SGA and LGA neonates, intrauterine fetal demise (IUFD) and neonatal mortality of SGA neonates, and neonatal shoulder dystocia and hypoglycemia as well as maternal third- and fourth-degree perineal lacerations in LGA pregnancies were evaluated.

RESULTS

The electronic search identified 237 records that were examined based on title and abstract, of which 27 full-text articles were examined for eligibility. After excluding seven articles, 20 observational studies were included in a Bayesian meta-analysis. Neonates classified as SGA according to customized growth charts had higher risks of IUFD (odds ratio (OR), 7.8 (95% CI, 4.2-12.3)), neonatal death (OR, 3.5 (95% CI, 1.1-8.0)), perinatal death (OR, 5.8 (95% CI, 3.8-7.8)) and NICU admission (OR, 3.6 (95% CI, 2.0-5.5)) than did non-SGA cases. Neonates classified as SGA according to population-based growth charts also had increased risk for adverse outcomes, albeit the point estimates of the pooled ORs were smaller: IUFD (OR, 3.3 (95% CI, 1.9-5.0)), neonatal death (OR, 2.9 (95% CI, 1.2-4.5)), perinatal death (OR, 4.0 (95% CI, 2.8-5.1)) and NICU admission (OR, 2.4 (95% CI, 1.7-3.2)). For LGA vs non-LGA, there were no differences in pooled ORs for perinatal death, NICU admission, hypoglycemia and maternal third- and fourth-degree perineal lacerations when classified according to either the customized or the population-based approach. In contrast, both approaches indicated that LGA neonates are at increased risk for shoulder dystocia than are non-LGA ones (OR, 7.4 (95% CI, 4.9-9.8) using customized charts; OR, 8.0 (95% CI, 5.3-10.1) using population-based charts).

CONCLUSIONS

Both customized and population-based growth charts can identify SGA neonates at risk for adverse outcomes. Although the point estimates of the pooled ORs may differ for some outcomes, the overlapping CIs and lack of direct comparisons prevent conclusions from being drawn on the superiority of one method. Future clinical trials should compare directly the two approaches in the management of fetuses of abnormal size. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Practice Bulletin No. 173: Fetal Macrosomia

Suspected fetal macrosomia is encountered commonly in obstetric practice. As birth weight increases, the likelihood of labor abnormalities, shoulder dystocia, birth trauma, and permanent injury to the neonate increases. The purpose of this document is to quantify those risks, address the accuracy and limitations of methods for estimating fetal weight, and suggest clinical management for a pregnancy with suspected fetal macrosomia.

Is cerebroplacental ratio a marker of impaired fetal growth velocity and adverse pregnancy outcome?

BACKGROUND

The cerebroplacental ratio has been proposed as a marker of failure to reach growth potential near term. Low cerebroplacental ratio, regardless of the fetal size, is independently associated with the need for operative delivery for presumed fetal compromise and with neonatal unit admission at term.

OBJECTIVE

The main aim of this study was to evaluate whether the cerebroplacental ratio at term is a marker of reduced fetal growth rate. The secondary aim was to investigate the relationship between a low cerebroplacental ratio at term, reduced fetal growth velocity, and adverse pregnancy outcome.

STUDY DESIGN

This was a retrospective cohort study of singleton pregnancies in a tertiary referral center. The abdominal circumference was measured at 20-24 weeks' gestation and both abdominal circumference and fetal Dopplers recorded at or beyond 35 weeks, within 2 weeks of delivery. Abdominal circumference and birthweight values were converted into Z scores and centiles, respectively, and fetal Doppler parameters into multiples of median, adjusting for gestational age. Abdominal circumference growth velocity was quantified using the difference in the abdominal circumference Z score, comparing the scan at or beyond 35 weeks with the scan at 20-24 weeks. Both univariable and multivariable logistic regression analyses were performed to investigate the association between low cerebroplacental ratio and the low abdominal circumference growth velocity (in the lowest decile) and to identify and adjust for potential confounders. As a sensitivity analysis, we refitted the model excluding the data on pregnancies with small-for-gestational-age neonates.

RESULTS

The study included 7944 pregnancies. Low cerebroplacental ratio multiples of median was significantly associated with both low abdominal circumference growth velocity (adjusted odds ratio, 2.10; 95% confidence interval, 1.71-2.57, P <0.001) and small for gestational age (adjusted odds ratio, 3.60; 95% confidence interval, 3.04-4.25, P < .001). After the exclusion of pregnancies resulting in small-for-gestational-age neonates, a low cerebroplacental ratio multiples of the median remained significantly associated with both low abdominal circumference growth velocity (adjusted odds ratio, 1.76; 95% confidence interval, 1.34-2.30, P < .001) and birthweight centile (adjusted odds ratio, 0.99; 95% confidence interval, 0.998-0.995, P < .001). The need for operative delivery for fetal compromise was significantly associated with a low cerebroplacental ratio (adjusted odds ratio, 1.40; 95% confidence interval, 1.10-1.78, P = .006), even after adjusting for both the umbilical artery pulsatility index multiples of the median and middle cerebral artery pulsatility index multiples of median. The results were similar, even after the exclusion of pregnancies resulting in small-for-gestational-age neonates (adjusted odds ratio, 1.39; 95% confidence interval, 1.06-1.84, P = .018). Low cerebroplacental ratio multiples of the median remained significantly associated with the risk of operative delivery for presumed fetal compromise (P < .001), even after adjusting for the known antenatal and intrapartum risk factors. These associations persisted, even after the exclusion of small-for-gestational-age births. In appropriate-for-gestational-age-sized fetuses, abdominal circumference growth velocity was significantly lower in those with a low cerebroplacental ratio multiples of the median than in those with normal cerebroplacental ratio multiples of the median (P < .001).

CONCLUSION

The cerebroplacental ratio is a marker of impaired fetal growth velocity and adverse pregnancy outcome, even in fetuses whose size is considered appropriate using conventional biometry.

Single and Serial Fetal Biometry to Detect Preterm and Term Small- and Large-for-Gestational-Age Neonates: A Longitudinal Cohort Study

Objectives

To assess the value of single and serial fetal biometry for the prediction of small- (SGA) and large-for-gestational-age (LGA) neonates delivered preterm or at term.

Methods

A cohort study of 3,971 women with singleton pregnancies was conducted from the first trimester until delivery with 3,440 pregnancies (17,334 scans) meeting the following inclusion criteria: 1) delivery of a live neonate after 33 gestational weeks and 2) two or more ultrasound examinations with fetal biometry parameters obtained at ≤36 weeks. Primary outcomes were SGA (<5^th centile) and LGA (>95^th centile) at birth based on INTERGROWTH-21^st gender-specific standards. Fetus-specific estimated fetal weight (EFW) trajectories were calculated by linear mixed-effects models using data up to a fixed gestational age (GA) cutoff (28, 32, or 36 weeks) for fetuses having two or more measurements before the GA cutoff and not already delivered. A screen test positive for single biometry was based on Z-scores of EFW at the last scan before each GA cut-off so that the false positive rate (FPR) was 10%. Similarly, a screen test positive for the longitudinal analysis was based on the projected (extrapolated) EFW at 40 weeks from all available measurements before each cutoff for each fetus.

Results

Fetal abdominal and head circumference measurements, as well as birth weights in the Detroit population, matched well to the INTERGROWTH-21^st standards, yet this was not the case for biparietal diameter (BPD) and femur length (FL) (up to 9% and 10% discrepancy for mean and confidence intervals, respectively), mainly due to differences in the measurement technique. Single biometry based on EFW at the last scan at ≤32 weeks (GA IQR: 27.4–30.9 weeks) had a sensitivity of 50% and 53% (FPR = 10%) to detect preterm and term SGA and LGA neonates, respectively (AUC of 82% both). For the detection of LGA using data up to 32- and 36-week cutoffs, single biometry analysis had higher sensitivity than longitudinal analysis (52% vs 46% and 62% vs 52%, respectively; both p<0.05). Restricting the analysis to subjects with the last observation taken within two weeks from the cutoff, the sensitivity for detection of LGA, but not SGA, increased to 65% and 72% for single biometry at the 32- and 36-week cutoffs, respectively. SGA screening performance was higher for preterm (<37 weeks) than for term cases (73% vs 46% sensitivity; p<0.05) for single biometry at ≤32 weeks.

Conclusions

When growth abnormalities are defined based on birth weight, growth velocity (captured in the longitudinal analysis) does not provide additional information when compared to the last measurement for predicting SGA and LGA neonates, with both approaches detecting one-half of the neonates (FPR = 10%) from data collected at ≤32 weeks. Unlike for SGA, LGA detection can be improved if ultrasound scans are scheduled as close as possible to the gestational-age cutoff when a decision regarding the clinical management of the patient needs to be made. Screening performance for SGA is higher for neonates that will be delivered preterm.

Association between sonographic measurement of fetal head circumference and labor outcome

OBJECTIVE

To evaluate the association between sonographically measured head circumference (HC) and labor outcome.

METHODS

In a retrospective study at a tertiary medical center in Israel, data were reviewed for all term singleton deliveries between July 2007 and December 2012 with HC measurements up to 7days before delivery. HC was compared between women with operative vaginal delivery (OVD) or cesarean delivery for prolonged second stage and those with normal vaginal delivery. The impact of HC above the 75th percentile on pregnancy outcome was analyzed.

RESULTS

The study included 2351 women, of whom 2045 (87.0%) had a normal vaginal delivery, 259 (11.0%) underwent OVD, and 47 (2.0%) cesarean. Each 10mm increase in HC was associated with increased risk for obstetric intervention because of a prolonged second stage (adjusted odds ratio [aOR] 1.26; 95% confidence interval [CI] 1.08-1.46). HC above the 75th percentile was independently associated with increased odds of OVD (aOR 1.77; 95% CI 1.30-2.41), 1-minute Apgar score less than 7 (aOR 2.91; 95% CI 1.50-5.66), and neonatal asphyxia (aOR 2.19; 95% CI 1.02-4.71).

CONCLUSION

Term HC above the 75th percentile was associated with increased rates of obstetric interventions because of a prolonged second stage and might be associated with neonatal asphyxia.

Relation between birth weight and weight and height at the age of 2 in children born preterm

OBJECTIVE

The aim of the study was to evaluate associations between fetal growth and weight at 2 years in infants born preterm using a customized approach for birth weight.

STUDY DESIGN

This is a secondary analysis of a multicenter trial that included a 2-year follow-up of children born prematurely. Customized birth weight percentiles were calculated using the Gardosi model for a U.S. population, and the relation between customized percentile and weight and height at 2 years (adjusted for gender using z-score) was determined using regression analysis and by comparing z-scores for children with birth weight <10th versus ≥10th percentile.

RESULTS

Weight z-score at 2 years was significantly lower in the <10th than in the ≥10th percentile group (median [interquartile range, IQR]: -0.66 [-1.58, -0.01] vs. -0.23 [-1.05, 0.55]; p < 0.001), and remained after adjusting for maternal education (p < 0.001). A similar relationship was noted for height z-score between groups (median [IQR]: -0.56 [-1.29, 0.19] vs. -0.24 [-0.99, 0.37]; p < 0.001). Positive relationships between customized birth weight percentile and weight and height at 2 years were noted (p < 0.001 for both), but were not strong (R (2) = 0.04 and 0.02, respectively).

CONCLUSION

Customized birth weight percentile is a minor determinant of weight at 2 years among children born preterm.

Differences in risk factors for incident and recurrent small-for-gestational-age birthweight: a hospital-based cohort study

OBJECTIVE

Examine whether small-for-gestational-age (SGA) risk factors differed by prior SGA birth.

DESIGN

Hospital-based cohort study.

SETTING

Utah, USA.

POPULATION

Electronic medical record data from 25,241 women who were nulliparous at study entry with ≥2 subsequent consecutive singleton deliveries (2002-2010).

METHODS

Estimated adjusted relative risks (RR) and 95% confidence intervals (95% CI) for the association between second pregnancy characteristics and SGA risk. Tested for risk factor differences between recurrence and incidence (Pdifference).

MAIN OUTCOME MEASURES

Second pregnancy incident (n = 1067) and recurrent SGA (n = 484) determined using a population-based reference.

RESULTS

SGA complicated 20.3 and 4.5% of deliveries to women with and without a prior SGA birth, respectively. Young maternal age (Pdifference = 0.01) and pregnancy hypertensive diseases (Pdifference = 0.03) were associated with incident but not recurrent SGA. Significant risk factors for incidence and recurrence were smoking (incident RR = 1.64 [95% CI 1.22-2.19]; recurrent RR = 1.59 [95% CI 1.17-2.17]), short stature (incident RR = 1.34 [95% CI 1.16-1.54]; recurrent RR = 1.54 [95% CI 1.31-1.82]), prepregnancy underweight (incident RR = 1.32 [95% CI 1.07-1.64]; recurrent RR = 1.30 [95% CI 1.03-1.64]), and inadequate weight gain (incident RR = 1.41 [95% CI 1.22-1.64]; recurrent RR = 1.33 [95% CI 1.10-1.60]). Race-ethnicity, marital or insurance status, alcohol, diabetes, asthma, thyroid disease, depression, or interpregnancy interval were not associated with incidence or recurrence.

CONCLUSION

There was considerable overlap in the risk factors for SGA recurrence and incidence. Recurrence and incidence risk factors included smoking, short stature, underweight, and inadequate weight gain. Maternal age and hypertensive diseases increased the risk for incidence only. Regardless of the SGA definition, some potentially modifiable risk factors for recurrence were identified.