Outcome-based comparative analysis of five fetal growth velocity models to define slow growth.

OBJECTIVE: Fetal growth surveillance includes assessment of size as well as rate of growth, and various definitions for slow growth have been adopted into clinical use. The aim of this study was to evaluate the effectiveness of different models to identify stillbirth risk, in addition to risk represented by the fetus being small-for-gestational age (SGA). METHODS: This was a retrospective analysis of a routinely collected and anonymized dataset of pregnancies that had two or more third-trimester ultrasound measurements of estimated fetal weight (EFW). SGA was defined as EFW < 10th customized centile, and slow growth was defined according to five published models in clinical use: (1) a fixed velocity limit of 20 g per day (FVL20 ); (2) a fixed > 50 centile drop, regardless of scan-measurement interval (FCD50 ); (3) a fixed > 30 centile drop, regardless of scan interval (FCD30 ); (4) growth trajectory slower than the third customized growth-centile limit (GCL3 ); and (5) EFW at second scan below the projected optimal weight range (POWR), based on partial receiver-operating-characteristics-curve-derived  cut-offs specific to the scan interval. RESULTS: The study cohort consisted of 164 718 pregnancies with 480 592 third-trimester ultrasound scans (mean ± SD, 2.9 ± 0.9). The last two scans in each pregnancy were performed at an average gestational age of 33 + 5 and 37 + 1 weeks. At the last scan, 12 858 (7.8%) EFWs were SGA, and of these, 9359 were also SGA at birth (positive predictive value, 72.8%). The rate at which slow growth was defined varied considerably (FVL20 , 12.7%; FCD50 , 0.7%; FCD30 , 4.6%; GCL3 , 19.8%; POWR, 10.1%), and there was varying overlap between cases identified as having slow growth and those identified as SGA at the last scan. Only the POWR method identified additional non-SGA pregnancies with slow growth (11 237/16 671 (67.4%)) that had significant stillbirth risk (relative risk, 1.58 (95% CI, 1.04-2.39)). These non-SGA cases resulting in stillbirth had a median EFW centile of 52.6 at the last scan and a median weight centile of 27.3 at birth. Subgroup analysis identified methodological problems with the fixed-velocity model because it assumes linear growth throughout gestation, and with the centile-based methods because the non-parametric distribution of centiles at the extremes does not reflect actual difference in weight gain. CONCLUSION: Comparative analysis of five clinically used methods to define slow fetal growth has shown that only the measurement-interval-specific POWR model can identify non-SGA fetuses with slow growth that are at increased risk of stillbirth. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Fetal weight projection model to define growth velocity and validation against pregnancy outcome in a cohort of serially scanned pregnancies.

OBJECTIVE: Fetal growth assessment is central to good antenatal care, yet there is a lack of definition of normal and abnormal fetal growth rate which can identify pregnancies at risk of adverse outcome. The aim of this study was to develop and test a model for defining normal limits of growth velocity which are specific to the fetal weight measurement interval. METHODS: The cohort consisted of 102 138 singleton pregnancies which underwent at least two third-trimester measurements of ultrasound estimated fetal weight (EFW), usually carried out because routine early-pregnancy risk assessment had indicated an increased risk of fetal growth restriction. We projected the EFW from the first of each consecutive measurement pair along its own centile rank to the gestational age of the second scan. Normal growth was defined as the second EFW being within a weight range based on limits derived by partial receiver-operating-characteristics-curve (pROC) analyses for small-for-gestational-age (SGA; < 10th centile) and large-for-gestational-age (LGA; > 90th centile) birth weight. The limits were measurement-interval specific and calculated for a fixed false-positive rate (FPR) of 10%. The resultant normal, slow and accelerated growth rates calculated from consecutive EFW pairs were evaluated against the following predefined perinatal outcome measures: stillbirth, neonatal death, SGA and LGA at birth, 5-min Apgar score < 7 and admission to the neonatal intensive care unit. Slow growth based on the last two scans was compared with SGA fetal weight (EFW < 10th centile) at the last scan and association with stillbirth risk was assessed, expressed as relative risk (RR) with 95% CI. RESULTS: The optimal cut-off limits for normal growth rate between consecutive scans varied according to the length of the measurement interval, with an average of -8.0% for slow growth and + 9.3% for accelerated growth at a fixed FPR of 10%. Slow growth between random consecutive scan pairs was associated significantly with all predefined outcome measures including stillbirth (RR, 2.19; 95% CI, 1.84-2.53) and neonatal death (RR, 2.28; 95% CI, 1.60-3.13). Accelerated growth was associated with LGA at birth (RR, 2.15; 95% CI, 2.10-2.20), while normal growth was protective of all adverse outcome measures. Slow growth between the last two scans (which were performed at a median gestational age of 33 + 1 to 36 + 4 weeks) and SGA at the last scan were each predictors of stillbirth, and stillbirth risk was highest when both were present (RR, 2.65; 95% CI, 1.67-4.20). However, 66.2% of pregnancies with slow growth were not SGA at the last scan and these cases also had an increased risk of stillbirth (RR, 2.07; 95% CI, 1.40-3.05). CONCLUSION: Fetal growth velocity defined by projected, measurement-interval specific fetal weight limits is associated independently with perinatal outcome and should be used for antenatal surveillance in addition to assessment by fetal size. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Reduction of stillbirths in England from 2008 to 2017 according to uptake of the Growth Assessment Protocol: 10-year population-based cohort study.

OBJECTIVE: Antenatal detection of small-for-gestational age (SGA) can reduce significantly the risk of stillbirth. The Growth Assessment Protocol (GAP) was developed to address the problem that most SGA fetuses are missed antenatally. We set out to analyze the effect that the GAP program has had on stillbirth rates in England. METHODS: We analyzed data from 2008 (the year before roll-out of the GAP program) to 2017 (latest available Office for National Statistics (ONS) unit-based data). The program consists of five elements: training, evidence-based guidelines for risk assessment and surveillance of fetal growth, customized charts, recording of process and outcome indicators, and audit of missed SGA cases. All maternity units in England were categorized into one of three groups according to their GAP status in 2017: (1) not in the GAP program; (2) GAP implemented partially (incomplete adoption of protocol, no monitoring and audit); and (3) GAP implemented completely. A subset of the complete-implementation group comprised the 20 units with the highest SGA detection rates. Unit-level live-birth and stillbirth data were obtained from the ONS for each of these groups. RESULTS: Stillbirth rates declined across all groups from 2008 to 2017, and significantly more in units in which GAP was implemented completely than in the non-GAP units (P < 0.05). The steepest decline in stillbirth rate was observed in the 20 units with the highest SGA detection rates, which had a 24% lower stillbirth rate compared with the units not using GAP (P < 0.01) in 2017. This difference remained significant after mixed-effects logistic regression analysis of potential confounding, including social deprivation (odds ratio, 0.76 (95% CI, 0.64-0.90)). Assessment of the nine Bradford Hill causality criteria and associated characteristics suggested that the association between implementation of the GAP program and reduction in stillbirth rate was causal. CONCLUSIONS: There has been an overall reduction in stillbirth rates in England that is likely to be a result of increased awareness of the importance of antenatal detection of SGA as a key risk factor for stillbirth. The decline in stillbirth rates was significantly greater in maternity units that had fully implemented the GAP program, and was most pronounced in the units with the highest antenatal SGA detection rates. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Making stillbirths visible: a systematic review of globally reported causes of stillbirth.

BACKGROUND: Stillbirth is a global health problem. The World Health Organization (WHO) application of the International Classification of Diseases for perinatal mortality (ICD-PM) aims to improve data on stillbirth to enable prevention. OBJECTIVES: To identify globally reported causes of stillbirth, classification systems, and alignment with the ICD-PM. SEARCH STRATEGY: We searched CINAHL, EMBASE, Medline, Global Health, and Pubmed from 2009 to 2016. SELECTION CRITERIA: Reports of stillbirth causes in unselective cohorts. DATA COLLECTION AND ANALYSIS: Pooled estimates of causes were derived for country representative reports. Systems and causes were assessed for alignment with the ICD-PM. Data are presented by income setting (low, middle, and high income countries; LIC, MIC, HIC). MAIN RESULTS: Eighty-five reports from 50 countries (489 089 stillbirths) were included. The most frequent categories were Unexplained, Antepartum haemorrhage, and Other (all settings); Infection and Hypoxic peripartum (LIC), and Placental (MIC, HIC). Overall report quality was low. Only one classification system fully aligned with ICD-PM. All stillbirth causes mapped to ICD-PM. In a subset from HIC, mapping obscured major causes. CONCLUSIONS: There is a paucity of quality information on causes of stillbirth globally. Improving investigation of stillbirths and standardisation of audit and classification is urgently needed and should be achievable in all well-resourced settings. Implementation of the WHO Perinatal Mortality Audit and Review guide is needed, particularly across high burden settings. FUNDING: HR, SH, SHL, and AW were supported by an NHMRC-CRE grant (APP1116640). VF was funded by an NHMRC-CDF (APP1123611). TWEETABLE ABSTRACT: Urgent need to improve data on causes of stillbirths across all settings to meet global targets. PLAIN LANGUAGE SUMMARY: Background and methods Nearly three million babies are stillborn every year. These deaths have deep and long-lasting effects on parents, healthcare providers, and the society. One of the major challenges to preventing stillbirths is the lack of information about why they happen. In this study, we collected reports on the causes of stillbirth from high-, middle-, and low-income countries to: (1) Understand the causes of stillbirth, and (2) Understand how to improve reporting of stillbirths. Findings We found 85 reports from 50 different countries. The information available from the reports was inconsistent and often of poor quality, so it was hard to get a clear picture about what are the causes of stillbirth across the world. Many different definitions of stillbirth were used. There was also wide variation in what investigations of the mother and baby were undertaken to identify the cause of stillbirth. Stillbirths in all income settings (low-, middle-, and high-income countries) were most frequently reported as Unexplained, Other, and Haemorrhage (bleeding). Unexplained and Other are not helpful in understanding why a baby was stillborn. In low-income countries, stillbirths were often attributed to Infection and Complications during labour and birth. In middle- and high-income countries, stillbirths were often reported as Placental complications. Limitations We may have missed some reports as searches were carried out in English only. The available reports were of poor quality. Implications Many countries, particularly those where the majority of stillbirths occur, do not report any information about these deaths. Where there are reports, the quality is often poor. It is important to improve the investigation and reporting of stillbirth using a standardised system so that policy makers and healthcare workers can develop effective stillbirth prevention programs. All stillbirths should be investigated and reported in line with the World Health Organization standards.

The WHO application of ICD-10 to deaths during the perinatal period (ICD-PM): results from pilot database testing in South Africa and United Kingdom.

OBJECTIVE: To apply the World Health Organization (WHO) Application of the International Classification of Diseases, tenth revision (ICD-10) to deaths during the perinatal period: ICD-Perinatal Mortality (ICD-PM) to existing perinatal death databases. DESIGN: Retrospective application of ICD-PM. SETTING: South Africa, UK. POPULATION: Perinatal death databases. METHODS: Deaths were grouped according to timing of death and then by the ICD-PM cause of death. The main maternal condition at the time of perinatal death was assigned to each case. MAIN OUTCOME MEASURES: Causes of perinatal mortality, associated maternal conditions. RESULTS: In South Africa 344/689 (50%) deaths occurred antepartum, 11% (n = 74) intrapartum and 39% (n = 271) in the early neonatal period. In the UK 4377/9067 (48.3%) deaths occurred antepartum, with 457 (5%) intrapartum and 4233 (46.7%) in the neonatal period. Antepartum deaths were due to unspecified causes (59%), chromosomal abnormalities (21%) or problems related to fetal growth (14%). Intrapartum deaths followed acute intrapartum events (69%); neonatal deaths followed consequences of low birthweight/ prematurity (31%), chromosomal abnormalities (26%), or unspecified causes in healthy mothers (25%). Mothers were often healthy; 53%, 38% and 45% in the antepartum, intrapartum and neonatal death groups, respectively. Where there was a maternal condition, it was most often maternal medical conditions, and complications of placenta, cord and membranes. CONCLUSIONS: The ICD-PM can be a globally applicable perinatal death classification system that emphasises the need for a focus on the mother-baby dyad as we move beyond 2015. TWEETABLE ABSTRACT: ICD-PM is a global system that classifies perinatal deaths and links them to maternal conditions.

Application of ICD-PM to preterm-related neonatal deaths in South Africa and United Kingdom.

OBJECTIVE: We explore preterm-related neonatal deaths using the WHO application of the International Classification of Disease (ICD-10) to deaths during the perinatal period: ICD-PM as an informative case study, where ICD-PM can improve data use to guide clinical practice and programmatic decision-making. DESIGN: Retrospective application of ICD-PM. SETTING: South Africa, and the UK. POPULATION: Perinatal death databases. METHODS: Descriptive analysis of neonatal deaths and maternal conditions present. MAIN OUTCOME MEASURES: Causes of preterm neonatal mortality and associated maternal conditions. RESULTS: We included 98 term and 173 preterm early neonatal deaths from South Africa, and 956 term and 3248 preterm neonatal deaths from the UK. In the South African data set, the main causes of death were respiratory/cardiovascular disorders (34.7%), low birthweight/prematurity (29.2%), and disorders of cerebral status (25.5%). Amongst preterm deaths, low birthweight/prematurity (43.9%) and respiratory/cardiovascular disorders (32.4%) were the leading causes. In the data set from the UK, the leading causes of death were low birthweight/prematurity (31.6%), congenital abnormalities (27.4%), and deaths of unspecified cause (26.1%). In the preterm deaths, the leading causes were low birthweight/prematurity (40.9%) and deaths of unspecified cause (29.6%). In South Africa, 61% of preterm deaths resulted from the maternal condition of preterm spontaneous labour. Among the preterm deaths in the data set from the UK, no maternal condition was present in 36%, followed by complications of placenta, cord, and membranes (23%), and other complications of labour and delivery (22%). CONCLUSIONS: ICD-PM can be used to appraise the maternal and newborn conditions contributing to preterm deaths, and can inform practice. TWEETABLE ABSTRACT: ICD-PM can be used to appraise maternal and newborn contributors to preterm deaths to improve quality of care.

Optimising the International Classification of Diseases to identify the maternal condition in the case of perinatal death.

OBJECTIVE: The WHO application of the tenth edition of the International Classification of Diseases (ICD-10) to deaths during the perinatal period (ICD Perinatal Mortality, ICD-PM) captures the essential characteristics of the mother-baby dyad that contribute to perinatal deaths. We compare the capture of maternal conditions in the existing ICD-PM with the maternal codes from the WHO application of ICD-10 to deaths during pregnancy, childbirth, and the puerperium (ICD Maternal Mortality, ICD-MM) to explore potential benefits in the quality of data received. DESIGN: Retrospective application of ICD-PM. SETTING: South Africa and the UK. POPULATION: Perinatal death databases. METHODS: The maternal conditions were classified using the ICD-PM groupings for maternal condition in perinatal death, and then mapped to the ICD-MM groupings of maternal conditions. MAIN OUTCOME MEASURES: Main maternal conditions in perinatal deaths. RESULTS: We reviewed 9661 perinatal deaths. The largest group (4766 cases, 49.3%) in both classifications captures deaths where there was no contributing maternal condition. Each of the other ICD-PM groups map to between three and six ICD-MM groups. If the cases in each ICD-PM group are re-coded using ICD-MM, each group becomes multiple, more specific groups. For example, the 712 cases in group M4 in ICD-PM become 14 different and more specific main disease categories when the ICD-MM is applied instead. CONCLUSIONS: As we move towards ICD-11, the use of the more specific, applicable, and relevant codes outlined in ICD-MM for both maternal deaths and the maternal condition at the time of a perinatal death would be preferable, and would provide important additional information about perinatal deaths. TWEETABLE ABSTRACT: Improving the capture of maternal conditions in perinatal deaths provides important actionable information.

Effectiveness of folic acid supplementation in pregnancy on reducing the risk of small-for-gestational age neonates: a population study, systematic review and meta-analysis.

OBJECTIVES: To assess the effect of timing of folic acid (FA) supplementation during pregnancy on the risk of the neonate being small for gestational age (SGA). DESIGN: A population database study and a systematic review with meta-analysis including the results of this population study. SETTING AND DATA SOURCES: A UK regional database was used for the population study and an electronic literature search (from inception until August 2013) for the systematic review. PARTICIPANTS AND INCLUDED STUDIES: Singleton live births with no known congenital anomalies; 111,736 in population study and 188,796 in systematic review. OUTCOME MEASURES, DATA EXTRACTION AND ANALYSIS: The main outcome was SGA based on customised birthweight centile. Associations are presented as odds ratios (OR) and adjusted odds ratios (aOR), adjusted for maternal and pregnancy-related characteristics. RESULTS: Of 108,525 pregnancies with information about FA supplementation, 92,133 (84.9%) had taken FA during pregnancy. Time of commencement of supplementation was recorded in 39,416 pregnancies, of which FA was commenced before conception in 10,036, (25.5%) cases. Preconception commencement of FA supplementation was associated with reduced risk of SGA <10th centile (aOR 0.80, 95% CI 0.71-0.90, P < 0.01) and SGA <5th centile (aOR 0.78, 95% CI 0.66-0.91, P < 0.01). This result was reproduced when the data were pooled with other studies in the systematic review, showing a significant reduction in SGA (<5th centile) births with preconception commencement of FA (aOR 0.75, 95% CI 0.61-0.92, P < 0.006). In contrast, postconception folate had no significant effect on SGA rates. CONCLUSION: Supplementation with FA significantly reduces the risk of SGA at birth but only if commenced preconceptually independent of other risk factors. SYSTEMATIC REVIEW REGISTRATION: This systematic review was prospectively registered with PROSPERO number CRD42013004895.

The experience of the implementation of perinatal audit in Moldova.

The Beyond the Numbers project in Moldova implemented perinatal mortality audit as a means to improve maternity and newborn care. Key activities for this project included training in audit, the setting up of audit committees, implementation of the review of cases and dissemination of information. During the project, a significant reduction was noted of perinatal deaths at term (from 37 weeks gestation and birthweight of ≥2500 g) by 1.5 per 1000; from 5.1 per 1000 in 2006 to 3.6 per 1000 in 2013.

Preventing stillbirths through improved antenatal recognition of pregnancies at risk due to fetal growth restriction.

Most stillbirths used to be categorized as 'unexplained' and were considered, by implication, unavoidable. Recent evidence indicates that they represent a combined challenge for public health and for clinical services. Independent case reviews have found that many deaths are associated with a failure to recognize risk factors and to afford them the appropriate standard of care. The majority of normally formed fetal deaths had preceding, unrecognized intrauterine growth failure. Improved training and adoption of standardized protocols has led to increased antenatal detection of fetal growth restriction, and this in turn has resulted in significant reductions in stillbirths in areas with high uptake of the training programme. A comprehensive, evidence-based growth assessment protocol (GAP) is currently being rolled out across the NHS to implement this strategy for stillbirth prevention.

Trisomies 18 and 13: trends in prevalence and prenatal diagnosis - population based study.

OBJECTIVE: The objective of this study was to determine trends in prenatal detection and current estimates of prevalence for trisomies 18 (T18) and 13 (T13) and their implications for screening policy. METHODS: We conducted a cohort study from a population-based regional anomaly register covering 995 003 births (1995-2009). RESULTS: There were 786 affected cases. Total prevalence of T18 increased from 3.95 in 1995-1999 to 6.94 per 10 000 births in 2005-2009 (annual trend χ(2) = 25.99, p < 0.001) and live birth prevalence, when adjusted for in utero attrition, increased from 1.47 to 2.30 per 10 000 births over the same time (annual trend χ(2) = 6.36, p = 0.01). For T18 and T13 combined, the proportion of cases diagnosed by prenatal karyotype or suspected by ultrasound increased from 85.1% (165/194) in 1995-1999 to 95.2% (299/314) in 2005-2009 (p < 0.001). In 2005-2009, 50.3% of prenatal cytogenetic diagnoses for T18 and 38.5% of T13 were made after the discovery of first trimester ultrasound anomalies, and the majority, 56.4% (185/328), of affected pregnancies were karyotyped or had ended before 18 weeks. CONCLUSION: T18 is increasing in prevalence because of maternal age and earlier surveillance. Prenatal diagnosis occurs mostly in the first trimester, without the intrinsic structures of a formal screening programme. These findings support the extension of first trimester combined screening to include T18 and T13.

Congenital lower urinary tract obstruction: a population-based epidemiological study.

OBJECTIVE: To determine the prevalence and outcome of lower urinary tract obstruction (LUTO), including the sensitivity of antenatal diagnosis. DESIGN: A retrospective population-based study. SETTING: Regional population-based congenital anomalies register (WMCAR). POPULATION: Fetuses affected by LUTO delivered between 1995 and 2007 to women resident in the West Midlands. METHODS: Cases were selected from the WMCAR using codes and keyword terms from the International Classification of Diseases, tenth revision (ICD10). Diagnoses were validated using additional data sets from Regional Fetal Medicine, Perinatal Pathology and Paediatric services. MAIN OUTCOME MEASURES: Rates of prevalence, prenatal diagnosis and mortality, with trends. RESULTS: There were 284 LUTO cases in 851 419 births during the study period, representing a total prevalence of 3.34 (2.95-3.72) per 10 000 births, and this prevalence did not change significantly over time. The prevalence of LUTO was significantly higher in Black and minority ethnic groups when compared with white Europeans (OR 2.38; 95% CI 1.87-3.03), and are associated with area-based deprivation measures (P < 0.01). Of all LUTO cases, 221 (77.8%) were isolated, and the remainder were associated with other structural or chromosomal anomalies. The most common subtype was posterior urethral valves (PUVs; n = 179, 63%). In total there were 211 (74.3%) cases of isolated, non-female, singleton fetuses that fitted the referral criteria for in utero vesico-amniotic shunting, giving a prevalence of 2.48 (2.14-2.81) per 10 000 live births. Within this group, the prenatal diagnosis rate was 46.9% (99/211). CONCLUSION: This is the largest population-based study of LUTO that has been performed to date, and provides accurate estimates for prevalence. The low prevalence and relatively low rate of antenatal detection limit the number of cases amenable to prenatal surgical intervention.

Development and evaluation of a standardized registry for diabetes in pregnancy using data from the Northern, North West and East Anglia regional audits.

OBJECTIVES: To develop and evaluate a standardized data set for measuring pregnancy outcomes in women with Type 1 and Type 2 diabetes and to compare recent outcomes with those of the 2002-2003 Confidential Enquiry into Maternal and Child Health. METHODS: Existing regional, national and international data sets were compared for content, consistency and validity to develop a standardized data set for diabetes in pregnancy of 46 key clinical items. The data set was tested retrospectively using data from 2007-2008 pregnancies included in three regional audits (Northern, North West and East Anglia). Obstetric and neonatal outcomes of pregnancies resulting in a stillbirth or live birth were compared with those from the same regions during 2002-2003. RESULTS: Details of 1381 pregnancies, 812 (58.9%) in women with Type 1 diabetes and 556 (40.3%) in women with Type 2 diabetes, were available to test the proposed standardized data set. Of the 46 data items proposed, only 16 (34.8%), predominantly the delivery and neonatal items, achieved ≥ 85% completeness. Ethnic group data were available for 746 (54.0%) pregnancies and BMI for 627 (46.5%) pregnancies. Glycaemic control data were most complete-available for 1217 pregnancies (88.1%), during the first trimester. Only 239 women (19.9%) had adequate pregnancy preparation, defined as pre-conception folic acid and first trimester HbA(1c) ≤ 7% (≤ 53 mmol/mol). Serious adverse outcome rates (major malformation and perinatal mortality) were 55/1000 and had not improved since 2002-2003. CONCLUSIONS: A standardized data set for diabetes in pregnancy may improve consistency of data collection and allow for more meaningful evaluation of pregnancy outcomes in women with pregestational diabetes.

Customized birthweight standard for an Iranian population.

OBJECTIVE: To produce a customized birthweight standard for Iran. METHOD: Retrospective study of a pregnancy database collected from five hospitals across Iran. The cohort consisted of 4994 consecutive term births with complete data, delivered between July 2013 and November 2014. Coefficients were derived using a backwards stepwise multiple regression technique. RESULTS: Maternal height, weight in early pregnancy and parity as well as the baby's sex were identified as significant physiological variables affecting birthweight. Paternal height and weight were also significant although weaker factors. The expected 280-day birthweight, free from pathological influences, of a standard size mother (height 163 cm, weight 64 kg) in her first pregnancy was 3390 g. Pathological factors found to affect birthweight in this cohort included village housing, anemia, preexisting and gestational diabetes and preeclampsia. CONCLUSION: The analysis confirmed the main physiological variables that affect birthweight in other countries and shows paternal factors also to be significant variables. Development of a country-specific customized birthweight standard will aid clinicians in Iran to distinguish between fetuses that are either constitutionally or pathologically small, thereby avoiding unnecessary interventions, and improving identification of at-risk pregnancies and perinatal outcome.

The value of customised centiles in assessing perinatal mortality risk associated with parity and maternal size.

OBJECTIVE: We wanted to compare customised and population standards for defining smallness for gestational age (SGA) in the assessment of perinatal mortality risk associated with parity and maternal size. DESIGN: Population-based cohort study. SETTING: Sweden. POPULATION: Swedish Birth Registry database 1992-1995 with 354 205 complete records. METHOD: Coefficients were derived and applied to determine SGA by the fully customised method, or by adjustment for fetal sex only, and using the same fetal weight standard. MAIN OUTCOME MEASURE: Perinatal deaths and rates of small for gestational age (SGA) babies within subgroups stratified by parity, body mass index (BMI) and maternal size within the BMI range of 20.0-24.9. RESULTS: Perinatal mortality rates (PMR) had a U-shaped distribution in parity groups, increased proportionately with maternal BMI, and had no association with maternal size within the normal BMI range. For each of these subgroups, SGA rates determined by the customised method showed strong association with the PMR. In contrast, SGA based on uncustomised, population-based centiles had poor correlation with perinatal mortality. The increased perinatal mortality risk in pregnancies of obese mothers was associated with an increased risk of SGA using customised centiles, and a decreased risk of SGA using population-based centiles. CONCLUSION: The use of customised centiles to determine SGA improves the identification of pregnancies which are at increased risk of perinatal death.

Should we customize fetal growth standards?

Several maternal and fetal physiological characteristics account for a substantial proportion of the variation in birth weight. These characteristics can be used to calculate an individualized optimal birth weight and to adjust or 'customize' the birth weight standard. Customized birth weight standards improve the distinction between constitutional and pathological smallness, and there is evidence that this finding can be extrapolated into the fetal period to evaluate intrauterine growth, but further studies are required to evaluate and quantify the effectiveness of customized versus conventional charts in improving the diagnosis of pathological smallness before birth.

Predictiveness of antenatal umbilical artery Doppler for adverse pregnancy outcome in small-for-gestational-age babies according to customised birthweight centiles: population-based study.

OBJECTIVE: To examine the relationship between smallness at birth and the predictive value of umbilical artery Doppler. DESIGN: Retrospective cohort. SETTING: Tertiary referral university hospital, Barcelona. POPULATION: A total of 7645 singleton pregnancies delivered between January 2002 and June 2004. METHODS: The associations with adverse outcome were assessed for small-for-gestational-age (SGA) babies according to customised standards who had normal and abnormal umbilical artery Doppler. MAIN OUTCOME MEASURES: Neonatal morbidity and perinatal mortality. RESULTS: Of the 369 SGA fetuses that had been identified antenatally, 70 (19%) had an abnormal umbilical artery Doppler and the babies from these pregnancies had a higher risk for neonatal morbidity when compared with babies with normal birthweight (OR 3.99, 95% CI 1.04-11.03). However, the remaining 299 (81%) fetuses with normal umbilical artery Doppler also had an elevated risk of neonatal morbidity (OR 2.26, 95% CI 1.04-4.39). Overall, many of the instances of adverse outcome associated with smallness for gestational age were attributable to the group with normal Doppler than to the group with abnormal Doppler. CONCLUSION: Normal antenatal umbilical artery Doppler cannot be taken as an indicator of low risk in pregnancies where the fetus is SGA according to customised percentiles.

Cerebral palsy and restricted growth status at birth: population-based case-control study.

OBJECTIVE: To evaluate the association between growth status at birth and subsequent development of cerebral palsy in preterm and term infants. DESIGN: Population-based case-controlled study. SETTING: Cerebral palsy register in Western Sweden. Subjects Cohort of 334 singletons born between 1983 and 1990, with cerebral palsy diagnosed from age 4, and 668 singletons matched for gestation, gender and delivery unit. METHOD: Growth status at birth was determined using small for gestational age (SGA) categories, with customised birthweight percentiles (SGAcust) based on the Swedish population. MAIN OUTCOME MEASURES: Proportion of babies that were SGAcust, comparing cases and controls in three gestational age categories: early preterm (24-33 weeks), late preterm (34-36 weeks) and term (37+ weeks). RESULTS: Of the 334 children with cerebral palsy, 87 (26.6%) were born early preterm, 27 (8.1%) late preterm and 218 (66%) at term. Children who had been born at term were more likely to have been SGA <1st customised percentile (SGAcust1) than their matched controls (OR 6.6, 95% CI 2.3-18.6). In contrast, children with cerebral palsy born preterm were not more likely to have been SGAcust1 (OR 0.9, 95% CI 0.4-1.9), and this applied to early preterm as well as late preterm births. For less severely small babies (SGA between 1st and 5th customised percentiles), the association with cerebral palsy remained significant for term births (OR 5.2, 95% CI 2.7-10.1) but was again not significant for preterm births. CONCLUSIONS: Term singletons with severely SGA birthweights had a five- to seven-fold risk of developing cerebral palsy compared with gestational age-matched infants with birthweights within normal limits. For children born preterm, SGA was not more likely to be present in cases than in controls. These findings support the concept of cerebral palsy as a multifactorial condition and highlight the importance of antenatal surveillance of fetal growth.