Gestational Age-specific Birthweight Research Articles

Birth Weight Reference Percentiles by Gestational Age for Turkish Twin Neonates.

Aims:In clinical practice, birth weight reference percentiles for singletons are used to evaluate twin births. The utilization of singleton reference percentiles for twins is not appropriate as they experience different growth trajectories. However, Turkey still lacks such references. Our aim was to create gestational age-specific birth weight references for female and male Turkish twins.Materials and Methods:This is a hospital-based, multi-centered, retrospective study. In total, 2544 live-born twins between 2010 and 2019 were included in the study. Gestational age, birth weight, mode of delivery, gender, birth order, chorionicity, maternal age, pregnancy resulting from assisted reproduction techniques, APGAR (Appearance, Pulse, Grimace, Activity, and Respiration) score at 5 minutes, admission to the neonatal intensive care unit (NICU), length of stay in NICU, and death during the NICU stay were recorded.Results:Smoothed reference curves for birth weight by gestational age and separate tables for female and male twin neonates for the 3rd, 10th, 50th, 90th, and 97th percentiles from 26 to 39 weeks of gestational age were constructed. Overall neonatal and infant mortality rates during NICU stay in our twin cohort were 12/1000 and 16/1000, respectively. Conclusion:Twin-specific birth weight nomograms could be helpful as a reference for clinicians to identify high-risk neonates and fetuses who need specialized care. However, further studies with larger series are urgently needed for validation and use of these nomograms in clinical practice.

Updated Gestational Age Specific Birthweight Reference of Hong Kong Chinese Newborns and Comparison with Local and International Growth Charts

Background: Different gestational age specific birthweight reference charts have been produced for different populations and ethnic groups over different time periods, mostly based on birthweight data. This study aims to update birthweight references for Hong Kong (HK) Chinese newborns to provide norms for identification of small and large for gestational age (SGA and LGA) fetuses, and to verify whether there are significant differences compared to previously published local reference charts, as well as to other southern Chinese and international data. Methods: All singleton Chinese livebirths delivered in United Christian Hospital from 2012 to 2017 were retrospectively included. The smoothed birthweight centiles at each gestation were computed. The birthweight centiles were then compared with other reference charts. Results: A total of 25,508 livebirths between 24 and 42 completed weeks of gestation were enrolled in the final analysis. The mean birthweights of our cohort were largely similar to previous studies at each gestation, but the 10th and 90th centile ranges differed significantly, so that the proportion of babies that would be classified as SGA or LGA varied widely using cut-offs from different studies. Older local studies tend to under-estimate, while the international growth charts would over-estimate the proportion of SGA babies. Conclusions: Updating fetal growth curve references based on local data is essential to establish more precise definitions of SGA and LGA babies in clinical management. The use of international growth charts in our population may not be appropriate and requires further validation.

EP19.12: Updated gestational age specific birthweight reference of Hong Kong Chinese newborns and comparison with previous studies

EP19.12: Updated gestational age specific birthweight reference of Hong Kong Chinese newborns and comparison with previous studies

Correlations between gestational age, birth weight and motor development in children with autism

Objective To explore the motor development and how it is influenced by gestational age and birth weight in children with autism, and provide evidence for the applications of motor development in the early diagnosis of autism. Methods A 1∶1 matched case-control study was conducted between 2012 and 2014.A total of 396 children under 5 years old with autism were enrolled in this study, their counterparts were healthy children 3 month younger/ older and with the same gender and residence.Guardians of participants were investigated using self-designed childhood psychological and behavioral development and related factors questionnaire.EpiData 3.0 software was used to establish the data base and SAS 9.4 software was used for data analysis. Results 396 pairs were enrolled in this study which including 342 pairs of boys(86.3%) and 54 pairs of girls(13.7%), the gender ratio was 6.33∶1; The average month age of case group was (39.44±11.99) months and (39.96±12.24) months for the control group.There was no significant difference observed in the distribution of birth weight(χ2=3.888, P=0.140) and gestational age specific birth weight(χ2=0.462, P=0.794)between two groups.But the distribution of gestational age was significantly different(χ2=9.476, P=0.009) .Children with autism have significant delaying in motor development compared with healthy children at same age, which including head lifting(3.50(1.00)month), rolling(6.00(3.50)month), sitting(8.00(2.50)month), etc.Preterm birth could have an effect on head lifting, rolling and sitting in children with autism, and also was the risk factor of delaying occurrence of head lifting(OR=2.911, 95%CI=1.491-5.681); Small for gestational age(SGA) was also a risk factor of delaying in walking(OR=1.703, 95%CI=1.053-2.754). Conclusion Evident delaying of motor development is observed among children with autism.Both preterm and SGA are risk factors for delayed motor development.Thus, early recognization of abnormities in motor development should raise awareness among caregivers and children care workers and assist in early diagnosis of children with autism. Key words: Autism; Preterm birth; Birth body weight; Gestational age specific birth weight

Paternal preconception folate intake in relation to gestational age at delivery and birthweight of newborns conceived through assisted reproduction.

Studies in rodents have shown that paternal folate intake prior to conception is associated with pregnancy and offspring outcomes. The aim of this study was to assess whether those associations might apply to humans as well. Between 2007 and 2017, the study prospectively analysed data from 108 couples participating in a preconception cohort of couples undergoing fertility treatment using their own gametes, whose treatment resulted in 113 pregnancies during the course of the study. Paternal and maternal preconception folate intake was assessed using a validated food frequency questionnaire. Linear mixed models were used to assess whether paternal preconception folate intake was associated with gestational age at delivery and gestational age-specific birthweight, while accounting for correlated data and potential confounders. In a multivariable-adjusted model, a 400μg/day increase in preconception paternal folate intake was associated with a 2.6-day longer gestation (95% confidence interval 0.8-4.3) after adjusting for potential confounders, including maternal folate intake. Similar associations were found for folate from food and supplements. Maternal folate intake was not associated with gestational age at delivery. Neither paternal nor maternal folate intake was associated with gestational-age-specific birthweight. Higher paternal preconception folate intake was associated with slightly longer gestation among live births achieved through assisted reproduction. The results suggest that preconception exposures of the father may have an impact on the health of his offspring, and therefore that preconception care should shift from a woman-centric to a couple-based approach.

Neonatal and fetal growth charts to identify preterm infants

It is unclear whether a neonatal or a fetal growth standard is a better predictor of adverse in-hospital newborn infant outcomes. We aimed to evaluate and compare the power of birthweight for gestational age to predict adverse neonatal outcomes using neonatal and fetal growth charts. Gestational age-specific birthweight was examined either as a percentile score or as a binary indicator for birthweight <10th percentile (small for gestational age) with the use of 3 fetal growth charts (National Institute of Child Health and Human Development, World Health Organization, and Intergrowth-21st) and 1 neonatal sex-specific birthweight chart. Inborn singleton infants from 2006-2014 with gestational age between 22 and 29 weeks and who were enrolled at 1 of the 852 US centers that were participating in the Vermont Oxford Network were studied. Outcomes included death, necrotizing enterocolitis, severe intraventricular hemorrhage, severe retinopathy of prematurity, and chronic lung disease. Receiver operating characteristic curve analysis was used to assess the predictive power of birthweight for gestational age, either as a score or as a small-for-gestational-age indicator, with the use of the 4 charts. We also examined the relative risks of the outcomes by comparing small-for-gestational-age and non-small-for-gestational-age infants with the use of the 4 charts. The percentage of small-for-gestational-age newborn infants ranged from 25.9-29.7% when with used the fetal growth charts. In contrast, the percentage was 10% when we used the neonatal charts. The areas under the receiver operating characteristic curves were similar across the 4 classification methods and were all <0.60, which suggests a poor predictive power. Small-for-gestational-age status, as classified by the neonatal chart, showed stronger associations with death, necrotizing enterocolitis, severe retinopathy of prematurity, and chronic lung disease, compared with those associations that were based on the other classification methods. Neither the neonatal nor the fetal growth charts are predictive of adverse infant in-hospital outcomes. In contrast to fetalcharts, the use of the neonatal charts results in stronger associationsbetween small-for-gestational-age and adverse outcomes.

Parental social position, in utero growth and risk of child development disorders: an administrative data based prospective cohort study

ABSTRACTObjectivesTo evaluate the influences of low birthweight and socioeconomic status upon child development disorders&#x0D; ApproachIt has been recognised that low birthweight and socio-economic status impact cognitive development in children. Previous studies in Scotland investigated this relationship using the Scottish Mental Health Survey 1932, the Growing Up in Scotland (GUS) longitudinal survey, and the Aberdeen Children of the 1950s study. This paper examines this using the Scottish Longitudinal Study (SLS) linked with Maternity Inpatient and Day Case records and Child Health Systems Programme Pre-School (CHSP Pre-School) records. This is original because it extends previous work through large-scale contemporary data which has been routinely collected and is representative of the Scottish population. It also includes a novel design through the use of birth data from parents and children recorded within the SLS.&#x0D; ResultsFrom this research it was identified that these child development measures were strongly associated with gestational-age specific birthweight and that fine motor, social and hearing abnormalities were much more likely for children with parents in lower grade occupations or who were long-term unemployed. These associations were net of other indicators of family socioeconomic position and birth outcomes, suggesting that infants from disadvantaged backgrounds remained more likely to experience these conditions beyond the differences that could be explained by other relevant factors (such as their birthweight).&#x0D; ConclusionThese findings confirm and build upon previous analysis through the use of linked administrative data.

Population-based birth weight reference percentiles for Chinese twins

Background: Birth weight percentiles by gestational age are important for assessing prenatal growth and predicting postnatal outcomes of newborns. Several countries have developed nation-specific birth weight references for twins, but China still lacks such references.Methods and results: Birth weight data for twins born between October 2006 and September 2015 were abstracted from the China National Population-based Birth Defects Surveillance System. A total of 54,786 live twin births aged ≥28 weeks of gestation without birth defects were included in the analysis. The LMS method was adopted to generate gestational age-specific birth weight percentiles and curves for male and female twins separately. Significant differences were observed between the current reference and other references developed for Chinese or non-Chinese twins. The neonatal mortality rate in this cohort was 12.3‰, and much higher rates at very early gestation weeks were identified in small-for-gestational-age twins grouped by the newly developed reference cutoffs.Conclusions: The established birth weight centiles represent the first birth weight norm for contemporary Chinese twins and can be a useful tool to assess growth of twins in clinical and research settings.Key MessagesThere have been no population-based birth weight percentiles for Chinese twins prior to this study. The established birth weight centiles for female and male twins are markedly lower than those for Chinese singletons. Twin-specific curves should be used for determining inappropriate for gestational age in twins rather than using existing singleton reference.The birth weight percentiles for twins differed significantly from those for non-Chinese twins. In addition to ethnic influences, the observed differences could be ascribed to variations in prenatal care, fetal or maternal nutrition status or other environmental factors.Neonatal mortality rates varied considerably among twins grouped by the newly developed reference percentiles. Small-for-gestational-age twins had much higher mortality than did appropriate-for-gestational-age twins, highlighting the need to reduce postnatal mortality by improving perinatal health care for twins.

Birth weight centiles, risk of intrapartum compromise, and adverse perinatal outcomes in term infants

Objective: The objective of this study is to evaluate the association between birth weight centiles and the risk of intrapartum compromise and adverse neonatal outcomes in term pregnancies. Methods: Retrospective study of 32 468 term singleton births at a major tertiary maternity hospital in Australia. Data comprised gestation, mode, and indication for delivery and adverse perinatal outcomes. Fetal sex and gestational age-specific birth weight centiles were the main exposure variable. Results: Neonates <21st birth weight centile had an increased risk of intrapartum compromise, the highest risk was in babies <3rd centile (OR 4.04, 95% CI 3.34–4.89). The risk of adverse perinatal outcomes was increased in neonates <21st and >91st birth weight centiles. The highest risk was in those <3rd centile (OR 2.35, 95% CI 2.00–2.75). Conclusions: Fetal size measurements near term may be used as part of screening test for identifying fetuses at an increased risk of intrapartum compromise and adverse perinatal outcomes.

Birth weight centiles by gestational age for twins born in south India.

BackgroundBirth weight centile curves are commonly used as a screening tool and to assess the position of a newborn on a given reference distribution. Birth weight of twins are known to be less than those of comparable singletons and twin-specific birth weight centile curves are recommended for use. In this study, we aim to construct gestational age specific birth weight centile curves for twins born in south India.MethodsThe study was conducted at the Christian Medical College, Vellore, south India. The birth records of all consecutive pregnancies resulting in twin births between 1991 and 2005 were reviewed. Only live twin births between 24 and 42 weeks of gestation were included. Birth weight centiles for gestational age were obtained using the methodology of generalized additive models for location, scale and shape (GAMLSS). Centiles curves were obtained separately for monochorionic and dichorionic twins.ResultsOf 1530 twin pregnancies delivered during the study period (1991–2005), 1304 were included in the analysis. The median gestational age at birth was 36 weeks (1st quartile 34, 3rd quartile 38 weeks). Smoothed percentile curves for birth weight by gestational age increased progressively till 38 weeks and levels off thereafter. Compared with dichorionic twins, monochorionic twins had lower birth weight for gestational age from after 27 weeks.ConclusionsWe provide centile values of birth weight at 24 to 42 completed weeks of gestation for twins born in south India. These charts could be used both in routine clinical assessments and epidemiological studies.

Maternal Serum 25-Hydroxyvitamin D Concentrations during Pregnancy and Infant Birthweight for Gestational Age: a Three-Cohort Study.

In response to inconsistent findings, we investigated associations between maternal serum 25-hydroxyvitamin D [25(OH)D] concentrations and infant birthweight for gestational age (BW/GA), including potential effect modification by maternal race/ethnicity and infant sex. Data from 2558 pregnant women were combined in a nested case-control study (preterm and term) sampled from three cohorts: the Omega study, the Pregnancy, Infection and Nutrition study, and the Pregnancy Outcomes and Community Health study. Maternal 25(OH)D concentrations were sampled at 4 to 29 weeks gestation (80% 14-26 weeks). BW/GA was modelled as sex and gestational age-specific birthweight z-scores. General linear regression models (adjusting for age, education, parity, pre-pregnancy body mass index, season at blood draw, and smoking) assessed 25(OH)D concentrations in relation to BW/GA. Among non-Hispanic Black women, the positive association between 25(OH)D concentrations and BW/GA was of similar magnitude in pregnancies with female or male infants [beta (β) = 0.015, standard error (SE) = 0.007, P = 0.025; β = 0.018, SE = 0.006, P = 0.003, respectively]. Among non-Hispanic White women, 25(OH)D-BW/GA association was observed only with male infants, and the effect size was lower (β = 0.008, SE = 0.003, P = 0.02). Maternal serum concentrations of 25(OH)D in early and mid-pregnancy were positively associated with BW/GA among non-Hispanic Black male and female infants and non-Hispanic White male infants. Effect modification by race/ethnicity may be due, in part, to overall lower concentrations of 25(OH)D in non-Hispanic Blacks. Reasons for effect modification by infant sex remain unclear.

Birth weight reference percentiles for Chinese.

ObjectiveTo develop a reference of population-based gestational age-specific birth weight percentiles for contemporary Chinese.MethodsBirth weight data was collected by the China National Population-based Birth Defects Surveillance System. A total of 1,105,214 live singleton births aged ≥28 weeks of gestation without birth defects during 2006–2010 were included. The lambda-mu-sigma method was utilized to generate percentiles and curves.ResultsGestational age-specific birth weight percentiles for male and female infants were constructed separately. Significant differences were observed between the current reference and other references developed for Chinese or non-Chinese infants.ConclusionThere have been moderate increases in birth weight percentiles for Chinese infants of both sexes and most gestational ages since 1980s, suggesting the importance of utilizing an updated national reference for both clinical and research purposes.

Growth and bone mineralization in small‐for‐gestational‐age preterm infants

Preterm infants are at risk for metabolic bone disease and suboptimal growth. This study examined the hypothesis that, apart from prematurity, intrauterine growth status (expressed as gestational age-specific birthweight standard deviation score) influences bone mineralization and body composition in early infancy. In this retrospective study, the groups consisted of preterm small-for-gestational-age (SGA) infants (n = 18; SGA group) and preterm appropriate-for-gestational-age (AGA) infants (n = 24; AGA group). Postnatal bone mineralization was measured at term-adjusted age (postmenstrual age, 37-42 weeks). Bone mineral content (BMC) and body composition were determined on dual-energy X-ray absorptiometry of the whole body. BMC and lean mass were significantly lower in the SGA group than in the AGA group at term-adjusted age (37-42 weeks postmenstrual age). Stepwise regression analysis identified weight at examination as the most significant factor, accounting for 51% of the variance in BMC. Bodyweight at term-adjusted age, rather than intrauterine growth, may affect postnatal bone mineralization in preterm low-birthweight infants. Therefore, promoting an increase in body size might increase postnatal bone mineralization in preterm SGA infants.

Birthweight centile charts from rural community-based data from Southern India

The objectives of the study were to estimate gestational age specific birthweight centiles from healthy pregnancies in a defined rural block and compare the under-two month mortality rates in those belonging to the lowest and highest centile groups. Retrospective chart review. Routine data collected regarding all pregnancies, births and deaths occurring in Kaniyambadi, a rural block in Southern India, between 2003 to 2012. All singleton live newborns of women without known major antenatal risk factors. Gestational age- and sex-specific birthweight centile curves were created using the LMS method. Mortality rates for the first two months of life were calculated for those in various centile groups. The median birthweight at term was lower for the study subjects as compared to the median birth weights in the WHO child growth standards 2006, the US and the UK standards. Mortality rates for those with birthweights both below the 3rd centile as well as above the 97th centile higher than for those between 3rd and 97th centiles. While absolute values of birthweights were lower than the WHO 2006 child growth standards there was a J shaped curve of birthweight and mortality. This suggests that in a given population, mortality increases at extremes of birthweights, even if some of these birthweights may be considered normal by other standards.

Influenza H1N1 vaccination and adverse pregnancy outcome

Although vaccines against influenza can reduce maternal morbidity and mortality, large-scale data on adverse effects in the offspring are scarce. Historical cohort study in Stockholm County, Sweden. We linked H1N1 vaccination data (Pandemrix(®), a mono-valent AS03 adjuvanted H1N1 vaccine) with pregnancy and birth data from 21,087 women with singleton offspring conceived between February 2009 and January 2010 (vaccinated during pregnancy: n=13,297 vs. unvaccinated: n=7,790). Data were analysed by conceptualizing the observational cohort as a series of nested cohorts defined at each week of gestation. Logistic regression estimated odds ratios (ORs) for low birth weight (LBW,<2,500g), preterm birth (<37 completed weeks), small-for-gestational age (SGA,<10th percentile of the gestational age-specific birth weight within the cohort), low 5-min Apgar score (<7), and caesarean section. Data were adjusted for potential confounders, including maternal age, body mass index, smoking, parity, civil status and comorbidities. Compared with infants of non-vaccinated women, infants of vaccinated women had similar adjusted ORs (95% CI) for LBW (0.91; 0.79-1.04), preterm birth (0.99; 0.89-1.10), SGA (0.97; 0.90-1.05), low Apgar score (1.05, 0.84-1.31), and a marginal risk reduction for caesarean section (0.94, 0.89-0.99). H1N1 vaccination during pregnancy, using an AS03-adjuvanted vaccine, does not appear to adversely influence offspring risks of LBW, preterm birth, SGA, or low Apgar score. Our results suggest that this vaccine is safe for the offspring when used in different stages of pregnancy.

A Mixture Model to Correct Misclassification of Gestational Age

Misclassification of gestational age based on the last menstrual period (LMP) in routinely collected data creates bias in newborn birthweight and gestational age-related indicators. Common correction methods have not been evaluated. We developed a normal mixture model for use with SAS software to correct misclassification of gestational age and compare its performance with other available correction methods and estimates of gestational age. Using the 2007 United States natality file from the National Center for Health Statistics, we compared LMP preterm and postterm birth rates and gestational age-specific birthweight percentiles against a reference subset of births, where the likelihood of misclassification in gestational age was minimized, before and after correction by a normal mixture model, two truncation methods, and the clinical/obstetric estimate of gestational age. The mixture model corrected preterm and postterm birth rates by 90% and 41% respectively, but previous methods performed poorly. The mixture model was also superior in correcting birthweight percentiles 50 and 90 with error reductions in the range of 68% to 85% between 28 and 36 weeks of gestation, where most misclassification occurred. The mixture model behaved consistently better than truncation methods, particularly between weeks 28 and 36 of gestation.

Leisure-Time Physical Activity in Pregnancy and the Birth Weight Distribution: Where Is the Effect?

Leisure-time physical activity (LTPA) is recommended during pregnancy and has been associated with lower risk of delivering a large infant. We sought to characterize the effect of LTPA across the entire birth weight distribution. Women enrolled in the Pregnancy Outcomes and Community Health (POUCH) Study (1998-2004) were followed-up in 2007. Follow-up efforts were extensive for a subcohort and minimal for the remainder (nonsubcohort). Thus, 596 subcohort and 418 nonsubcohort women who delivered at term participated. Offspring were categorized as small-, appropriate-, or large-for-gestational-age (SGA, AGA, and LGA, respectively) based on gender and gestational age-specific birth weight z-scores (BWz). At follow-up, women recalled pregnancy LTPA and were classified as inactive, insufficiently active or meeting LTPA recommendations. Linear, logistic, and quantile regression analyses were conducted separately by subcohort status. Meeting LTPA recommendations decreased odds of LGA significantly among the nonsubcohort (aOR = 0.30, 95% CI: 0.14-0.64) and nonsignificantly among the subcohort (aOR = 0.68, 95% CI: 0.34-1.34). In quantile regression, meeting LTPA recommendations reduced BWz among the upper quantiles in the nonsubcohort. LTPA during pregnancy lowered odds of LGA and reduced BWz among the upper quantiles, without shifting the entire distribution. LTPA during pregnancy may be useful for reducing risks of large fetal size.

Pre-natal and post-natal growth trajectories and childhood cognitive ability and mental health

Most studies of the associations between pre-natal or post-natal growth and cognitive ability have been based on children with pathologically slow growth measured between two time points only, rather than children with normal growth trajectories estimated from multiple measures of growth. We investigated the associations of pre-natal and post-natal trajectories in both weight and length/height through the first 5 years of life with cognitive ability and mental health at 6.5 years of age among healthy children. Our study is based on 11 899 children who were born healthy at ≥37 completed weeks with birth weight ≥2500 g and had up to 13 measures of weight and length/height from birth to age 5 years and cognitive ability and behaviour measured at 6.5 years. Using a linear spline random-effects model with 2 knots at 3 and 12 months, we estimated growth trajectories for each child from birth to age 5 years in weight and length/height in four periods: gestational age-specific birth weight and length (pre-natal 'growth'), early infancy (0-3 months), late infancy (3-12 months) and early childhood (1-5 years). We used generalized estimating equations to estimate mean differences in IQ and mental health according to pre-natal and post-natal growth trajectory. IQ was measured using the Wechsler Abbreviated Scales of Intelligence, and mental health was assessed using the Strengths and Difficulties Questionnaire. A 1 standard deviation (SD) in birth weight was positively associated with cognitive ability (0.82 IQ points, 95% CI: 0.54-1.10) after adjusting for confounders. For post-natal weight gain trajectories, a 1 SD faster weight gain was associated with an increase of 0.77 (95% CI: 0.42-1.11) IQ points for early infancy, 0.30 (95% CI: 0.02-0.58) points for late infancy, and 0.40 (95% CI: 0.04-0.76) for early childhood after adjusting for confounders and for earlier growth. For length/height trajectories, the magnitudes of increase in cognitive ability were similar to each other (~0.6 points) across the four periods. Pre-natal and infancy growth, but not early childhood growth, were associated with reduced externalising behaviours. Although the effect sizes are small and residual confounding cannot be excluded, our results suggest that among healthy children, faster growth from the pre-natal period through age 5 years is positively associated with cognitive ability, whereas faster growth in the pre-natal period and infancy is positively associated with mental health at early school age.

A nationwide investigation on gestational age specific birthweight and mortality among Japanese twins

Gestational age specific birthweight has been used as an important indicator to identify the health status of neonates and to provide appropriate neonatal care services to those at high risk. To identify the gestational age specific birthweight of twins born in secondary and tertiary hospitals in Japan and to explore factors affecting mortality, we used a nationwide obstetric database in Japan. Liveborn twins from 2001 to 2005 in the database, which was established with the national Perinatal Health Care Project, were enrolled (n=22,240). Obstetric data from the medical records were collected and analysed. Approximately 60% of liveborn twins were delivered between weeks 33 and 38, most frequently at 36 and 37 weeks. The mean birthweight of liveborn twins was 2084 g and the mean gestational age was 34.9 weeks. Intrauterine growth differed by parity, mode of delivery, birth order, chorionicity and sex. Using logistic regression, lower gestational age, small for gestational age, monochorionic twins and vaginal delivery tended to have higher risks of mortality.

594: The first reference for gestational age-specific birthweight curves and percentiles for Korean neonates

594: The first reference for gestational age-specific birthweight curves and percentiles for Korean neonates