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Cite this page: Hill, M.A. (2019, February 20) Embryology Birth Weight. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Birth_Weight
Association between Vitamin Intake during Pregnancy and Risk of Small for Gestational Age
Nutrients. 2017 Nov 23;9(12). pii: E1277. doi: 10.3390/nu9121277.
Salcedo-Bellido I1,2,3, Martínez-Galiano JM4,5,6,7, Olmedo-Requena R8,9,10, Mozas-Moreno J11,12, Bueno-Cavanillas A13,14,15, Jimenez-Moleon JJ16,17,18, Delgado-Rodríguez M19,20.
Pregnancy increases the requirements of certain nutrients, such as vitamins, to provide nutrition for the newborn. The aim was to analyze the association between dietary intake of vitamins during pregnancy and risk of having a small for gestational age (SGA) newborn. A matched case-control study was conducted (518 cases and 518 controls of pregnant women) in Spain. Dietary vitamin intake during pregnancy was assessed using a validated food frequency questionnaire, categorized into quintiles. Odds ratios (ORs) and their 95% confidence intervals (CI) were estimated with conditional regression logistic models. A protective association was observed between maternal dietary intake of vitamins A and D and SGA. For vitamin B3 and B6, the observed protective effect was maintained after adjusting for potential confounding factors. For vitamin B9, we found only an effect in quintiles 3 and 4 (OR = 0.64; 95% CI, 0.41-1.00; OR = 0.58; 95% CI, 0.37-0.91). Protective effect for vitamin B12 was observed in 4th and 5th quintiles (OR = 0.61; 95% CI, 0.39-0.95; OR = 0.68; 95% CI, 0.43-1.04). No associations were detected between dietary intake of vitamins B2, E and C intake and SGA. Our results suggest a positive association between dietary vitamin intake during pregnancy and the weight of the newborn, although more studies are necessary and there could be a ceiling effect for higher intakes of some vitamins cannot be discarded. KEYWORDS: dietary vitamins intake; maternal nutrition; pregnancy; small for gestational age PMID: 29168736 PMCID: PMC5748728 DOI: 10.3390/nu9121277
Birthweight and Childhood Cancer: Preliminary Findings from the International Childhood Cancer Cohort Consortium (I4C)
Paediatr Perinat Epidemiol. 2015 May 19. doi: 10.1111/ppe.12193. [Epub ahead of print]
Paltiel O1, Tikellis G2, Linet M3, Golding J4, Lemeshow S5, Phillips G6, Lamb K7, Stoltenberg C8,9, Håberg SE8, Strøm M10, Granstrøm C10, Northstone K11, Klebanoff M5,12, Ponsonby AL2,13, Milne E14, Pedersen M15,16,17,18,19, Kogevinas M15,17,18,20, Ha E21, Dwyer T2,13,22; International Childhood Cancer Cohort Consortium.
BACKGROUND: Evidence relating childhood cancer to high birthweight is derived primarily from registry and case-control studies. We aimed to investigate this association, exploring the potential modifying roles of age at diagnosis and maternal anthropometrics, using prospectively collected data from the International Childhood Cancer Cohort Consortium. METHODS: We pooled data on infant and parental characteristics and cancer incidence from six geographically and temporally diverse member cohorts [the Avon Longitudinal Study of Parents and Children (UK), the Collaborative Perinatal Project (USA), the Danish National Birth Cohort (Denmark), the Jerusalem Perinatal Study (Israel), the Norwegian Mother and Child Cohort Study (Norway), and the Tasmanian Infant Health Survey (Australia)]. Birthweight metrics included a continuous measure, deciles, and categories (≥4.0 vs. <4.0 kilogram). Childhood cancer (377 cases diagnosed prior to age 15 years) risk was analysed by type (all sites, leukaemia, acute lymphoblastic leukaemia, and non-leukaemia) and age at diagnosis. We estimated hazard ratios (HR) and 95% confidence intervals (CI) from Cox proportional hazards models stratified by cohort. RESULTS: A linear relationship was noted for each kilogram increment in birthweight adjusted for gender and gestational age for all cancers [HR = 1.26; 95% CI 1.02, 1.54]. Similar trends were observed for leukaemia. There were no significant interactions with maternal pre-pregnancy overweight or pregnancy weight gain. Birthweight ≥4.0 kg was associated with non-leukaemia cancer among children diagnosed at age ≥3 years [HR = 1.62; 95% CI 1.06, 2.46], but not at younger ages [HR = 0.7; 95% CI 0.45, 1.24, P for difference = 0.02]. CONCLUSION: Childhood cancer incidence rises with increasing birthweight. In older children, cancers other than leukaemia are particularly related to high birthweight. Maternal adiposity, currently widespread, was not demonstrated to substantially modify these associations. Common factors underlying foetal growth and carcinogenesis need to be further explored. © 2015 The Authors. Paediatric and Perinatal Epidemiology published by John Wiley & Sons Ltd. KEYWORDS: Childhood cancer; cohort studies; leukemia; pooled analysis.
Outcomes of neonates with birth weight⩽500 g: a 20-year experience
J Perinatol. 2015 May 7. doi: 10.1038/jp.2015.44.
Upadhyay K1, Pourcyrous M1, Dhanireddy R1, Talati AJ1.
OBJECTIVE: Ethical dilemmas continue regarding resuscitation versus comfort care in extremely preterm infants. Counseling parents and making decisions regarding the care of these neonates should be based on reliable, unbiased and representative data drawn from geographically defined populations. We reviewed survival and morbidity data for our population at the edge of viability. STUDY DESIGN: A retrospective review of our perinatal database was carried out to identify all infants born alive and admitted to the neonatal intensive care unit (NICU) with BW⩽500 g between 1989 and 2009. Data from the initial hospital stay and follow-up at 24 months were collected. RESULT: Out of 22 672 NICU admissions, 273 were eligible: 212 neonates were reviewed after excluding infants with comfort care. BW ranged from 285 to 500 g (mean 448 g) and gestational age range 22 to 28 weeks (median 24 week). Sixty-one (28.8%) survived until discharge. Only 13.8% males survived compared with 39.2% females (P<0.05). Half (49%) were discharged with home oxygen/monitor. Fifty (82%) patients' charts were available to review at the 24-month follow-up. Thirty-three percent of surviving infants had a normal neurodevelopmental assessment at 24 months. Forty-three percent had weight/head circumference<5th percentile at 24 months. CONCLUSION: About a third of neonates admitted to NICU with ⩽500 g BW survived, with 33% of those surviving, demonstrating age-appropriate development at a 24-month follow-up visit.Journal of Perinatology advance online publication, 7 May 2015; doi:10.1038/jp.2015.44.
Birth weight reference percentiles for Chinese
PLoS One. 2014 Aug 15;9(8):e104779. doi: 10.1371/journal.pone.0104779. eCollection 2014.
Dai L1, Deng C2, Li Y3, Zhu J1, Mu Y2, Deng Y1, Mao M4, Wang Y2, Li Q2, Ma S5, Ma X5, Zhang Y5.
OBJECTIVE: To develop a reference of population-based gestational age-specific birth weight percentiles for contemporary Chinese. METHODS: Birth 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. RESULTS: Gestational 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. CONCLUSION: There 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.
Birthweight percentiles by gestational age for births following assisted reproductive technology in Australia and New Zealand, 2002-2010
Hum Reprod. 2014 Jun 7. pii: deu120. [Epub ahead of print]
Li Z1, Wang YA1, Ledger W2, Sullivan EA3.
STUDY QUESTION: What is the standard of birthweight for gestational age for babies following assisted reproductive technology (ART) treatment? SUMMARY ANSWER: Birthweight for gestational age percentile charts were developed for singleton births following ART treatment using population-based data. WHAT IS KNOWN ALREADY: Small for gestational age (SGA) and large for gestational age (LGA) births are at increased risks of perinatal morbidity and mortality. A birthweight percentile chart allows the detection of neonates at high risk, and can help inform the need for special care if required. STUDY DESIGN, SIZE, DURATION: This population study used data from the Australian and New Zealand Assisted Reproduction Database (ANZARD) for 72 694 live born singletons following ART treatment between January 2002 and December 2010 in Australia and New Zealand. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 69 315 births (35 580 males and 33 735 females) following ART treatment were analysed for the birthweight percentile. Exact percentiles of birthweight in grams were calculated for each gestational week between Week 25 and 42 for fresh and thaw cycles by infant sex. Univariate analysis was used to determine the exact birthweight percentile values. Student t-test was used to examine the mean birthweight difference between male and female infants, between single embryo transfer (SET) and double embryo transfer (DET) and between fresh and thaw cycles. MAIN RESULTS AND THE ROLE OF CHANCE: Preterm births (birth before 37 completed weeks of gestation) and low birthweight (<2500 g) were reported for 9.7 and 7.0% of live born singletons following ART treatment. The mean birthweight was 3280 g for live born singletons following fresh cycles (3338 g for male infants and 3217 for female infants) and 3413 g for live born singletons following thaw cycles (3475 g for male infants and 3349 for female infants). The proportion of SGA for male ART births following thaw cycles at 35-41 weeks gestation was significantly lower than for the Australian general population, ranging from 3.8% (95% confidence interval (CI): 1.3%, 6.2%) at 35 weeks gestation to 7.9% (95% CI: 6.3%, 9.5%) at 41 weeks gestation. The proportion of LGA for male ART births following thaw cycles was significantly higher than for the Australian general population between 33 weeks (17.1%, 95% CI: 8.9%, 25.2%) and 41 weeks (14.4%, 95% CI: 12.3%, 16.5%). A similar trend was shown for female infants following thaw cycles. The live born singletons following SET were, on average, 45 g heavier than live born singletons following DET (P< 0.001). Overall, SGA was reported for 8.9% (95% CI: 8.6%, 9.1%) of live born singletons following SET and for 9.9% (95% CI: 9.5%, 10.3%) of live born singletons following DET. LIMITATIONS, REASONS FOR CAUTION: Birthweight percentile charts do not represent fetal growth standards but only the weight of live born infants at birth. WIDER IMPLICATIONS OF THE FINDINGS: The comparison of birthweight percentile charts for ART births and general population births provide evidence that the proportion of SGA births following ART treatment was comparable to the general population for SET fresh cycles and significantly lower for thaw cycles. Both fresh and thaw cycles showed better outcomes for singleton births following SET compared with DET. Policies to promote single embryo transfer should be considered in order to minimize the adverse perinatal outcomes associated with ART treatment. STUDY FUNDING/COMPETING INTERESTS: No specific funding was obtained. The authors have no conflicts of interest to declare. © The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: email@example.com. KEYWORDS: assisted reproductive technology; birthweight; gestational age; single embryo transfer; small for gestational age
Birth weight and subsequent blood pressure: a meta-analysis
Arch Cardiovasc Dis. 2012 Feb;105(2):99-113. Epub 2012 Feb 14.
Mu M, Wang SF, Sheng J, Zhao Y, Li HZ, Hu CL, Tao FB. Source School of Public Health, Anhui Medical University, Hefei, China.
Hypertension is becoming an important health problem in many countries. The 'small baby syndrome hypothesis' suggests that an inverse linear relationship exists between birth weight and later risk of hypertension; however, this relationship is under debate. We conducted a meta-analysis to examine the association between birth weight and subsequent blood pressure. Among 78 studies reporting on the association between birth weight and subsequent blood pressure, 20 articles (reporting 27 original studies) were eligible for inclusion. Low birth weight (< 2500 g) compared with birth weight greater than 2500 g was associated with an increased risk of hypertension (odds ratio [OR] 1.21; 95% confidence interval [CI] 1.13, 1.30); high birth weight (> 4000 g) compared with birth weight less than 4000 g was associated with a decreased risk of hypertension (OR 0.78; 95% CI 0.71, 0.86). When low birth weight (< 2500 g) was compared with birth weight greater than 2500 g, mean systolic blood pressure (SBP) increased by 2.28 mmHg (95% CI 1.24, 3.33); when high birth weight (> 4000 g) was compared with birth weight less than 4000 g, mean SBP decreased by 2.08 mmHg (95% CI -2.98, -1.17). These findings indicate that there is an inverse linear association between birth weight and later risk of hypertension, and that this association primarily exists between birth weight and SBP. Copyright Â© 2011 Elsevier Masson SAS. All rights reserved.
Birth-weight prediction by two- and three-dimensional ultrasound imaging
Ultrasound Obstet Gynecol. 2010 Apr;35(4):426-33.
Bennini JR, Marussi EF, Barini R, Faro C, Peralta CF. Source Department of Obstetrics and Gynecology, Center for Integral Assistance to Women's Health, State University of Campinas Medical School, Campinas, Brazil.
OBJECTIVES: To compare the accuracies of birth-weight predicting models derived from two-dimensional (2D) ultrasound parameters and from total fetal thigh volumes measured by three-dimensional (3D) ultrasound imaging; and to compare the performances of these formulae with those of previously published equations.
METHODS: A total of 210 patients were evaluated to create a formula-generating group (n = 150) and a prospective-validation group (n = 60). Polynomial regression analysis was performed on the first group to generate one equation based on 2D ultrasound measurements, one based on fetal thigh volume measured by the multiplanar technique (ThiM) and one based on fetal thigh volume obtained by the Virtual Organ Computer-aided AnaLysis (VOCAL()) method (ThiV). Paired-samples t-tests with Bonferroni adjustments were used to compare the performances of these equations in the formula-finding and the prospective-validation groups. The same approach was used to compare the accuracies of the new 2D and 3D formulae with those of both original and modified 2D equations from previous publications, as well as the 3D model reported by Chang et al.
RESULTS: The formulae with the best fit for the prediction of birth weight were: estimated fetal weight (EFW) = - 562.824 + 11.962x AC x FDL + 0.009 x BPD(2)x AC(2) (where AC is abdominal circumference, FDL is femur diaphysis length and BPD is biparietal diameter), EFW = 1033.286 + 12.733 x ThiM, and EFW = 1025.383 + 12.775 x ThiV. For both the formula-generating and the prospective-validation groups, there were no significant differences between the accuracies of the new 2D and 3D models in the prediction of birth weight. When applied to our population, the performances of the modified and original versions of the previously published 2D equations and the performance of the original 3D formula reported by Chang et al. were all significantly worse than our models.
CONCLUSIONS: We believe that the greatest sources of discrepancy in estimation of birth weight are the phenotypic differences among patients used to create each of the formulae mentioned in this study. Our data reinforce the need for customized birth-weight prediction formulae, regardless of whether 2D or 3D measurements are employed.
Copyright 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Estimate of birth weight using two- and three-dimensional ultrasonography
Rev Assoc Med Bras. 2010 Mar-Apr;56(2):204-8.
(Article in Portuguese)
Nardozza LM, Araújo Junior E, Vieira MF, Rolo LC, Moron AF. Source Departamento de Obstetrícia, Universidade Federal de São Paulo- Escola Paulista de Medicina - UNIFESP-EPM, São Paulo, SP. firstname.lastname@example.org Abstract OBJECTIVE: Assess and compare accuracy of birth weight prediction using a combination of two-dimensional (abdominal circumference - AC and femur length - FL) and three-dimensional parameters (fetal arm -VolArm and thigh -VolTh volumes).
METHODS: A cross sectional study was carried out involving 78 singleton, live, euploid fetuses without structural malformations born within 48 hours after ultrasonography. VolArm and VolTh were obtained by three-dimensional ultrasound using the multiplanar mode at 5 mm intervals. AC and FL were measured by two-dimensional ultrasound. Linear and polynomial regressions were calculated to determine the best formula to predict birth weight using VolArm, VolTh , CA and FL. ANOVA was used to compare errors in birth weight prediction using this formula and those obtained using the Shepard and Hadlock formulae.
RESULTS: The best formula for prediction of birth weight was a simple linear regression (Weight = -1486.1 + 60.5AC + 140.57FL + 16.6VolArm + 4.8VolTh), R2= 0.932. The error (E), absolute error (AE), percent error (PE) and absolute percent error (APE) for this new formula were 0 g, 0.2%, 112.2 g and 3.7%. This new formula had smaller E, AE, PE and APE than the Shepard formula and smaller AE and APE than Hadlock s formula.
CONCLUSION: A formula using VolArm, VolTh, AC and FL was more accurate for prediction of birth weight than formulae using only two-dimensional parameters.
A comparison of customized and population-based birth-weight standards: the influence of gestational age
Eur J Obstet Gynecol Reprod Biol. 2009 Sep;146(1):41-5. Epub 2009 Jul 5.
Hemming K, Hutton JL, Bonellie S. Source Department of Public Health, University of Birmingham, Birmingham B15 2TT, UK. email@example.com
OBJECTIVES: We examined how customized birth-weight standards compare to population birth-weight references at term (> or =37 weeks), nearly term (34-36 weeks), moderately preterm (32-33 weeks) and for the very preterm births (28-31 weeks), with respect to perinatal mortality. STUDY DESIGN: Data from the national Swedish Medical Births Register for the years 1992-2001, consisting of a total of 783,303 singletons born at or after 28 completed gestational weeks. Infants were classified as small for gestational age (SGA, <10th centile) according to a conventional population based birth-weight reference and a customized standard. Risk ratios (RR) for still birth and neonatal death were compared between standards by prematurity of the birth. Diagnostic performance measures of specificity, sensitivity and positive and negative predictive values were also evaluated. RESULTS: More than half, 59% (209), of the 355 infants still-born between 28 and 31 weeks gestation were classified as SGA by the customized standard, but only 23% (80), were so classified as SGA by the population reference. However, only 14% (95%CI 13-16) of the 1461 very preterm infants classified as SGA by the customized standard were still-born, compared to 23% (95%CI 19-28) of the 348 infants classified as SGA by the population reference. Therefore, the relative risk of still birth for those classified as SGA by the customized standard is lower, 2.02 (95%CI: 1.65, 2.46), than for the population reference 2.64 (95%CI: 2.11, 3.30). Similar results were observed for the risk of neonatal death. For term weeks, customized standards showed stronger relationships than population references (RR: 4.30 (95%CI 3.82, 4.84) vs. 4.00 (95%CI 3.55, 4.51) for still births). CONCLUSIONS: Customized standards categorize a higher absolute number of preterm infants who are still-born as SGA. However, infants classified as SGA by population references are at higher risk of perinatal mortality than infants classified as SGA by customized standards.
New fetal weight estimation models using fractional limb volume
Ultrasound Obstet Gynecol. 2009 Nov;34(5):556-65.
Lee W, Balasubramaniam M, Deter RL, Yeo L, Hassan SS, Gotsch F, Kusanovic JP, Gonçalves LF, Romero R. Source Division of Fetal Imaging, Department of Obstetrics and Gynecology, Oakland University William Beaumont School of Medicine, Royal Oak, MI 48073-6769, USA. firstname.lastname@example.org Abstract OBJECTIVES: The main goal of this study was to determine the accuracy and precision of new fetal weight estimation models, based on fractional limb volume and conventional two-dimensional (2D) sonographic measurements during the second and third trimesters of pregnancy.
METHODS: A prospective cross-sectional study of 271 fetuses was performed using three-dimensional ultrasonography to extract standard measurements-biparietal diameter (BPD), abdominal circumference (AC) and femoral diaphysis length (FDL)-plus fractional arm volume (AVol) and fractional thigh volume (TVol) within 4 days of delivery. Weighted multiple linear regression analysis was used to develop 'modified Hadlock' models and new models using transformed predictors that included soft tissue parameters for estimating birth weight. Estimated and observed birth weights were compared using mean percent difference (systematic weight estimation error) and the SD of the percent differences (random weight estimation error). The proportion of newborns with estimated birth weight within 5 or 10% of actual birth weight were compared using McNemar's test.
RESULTS: Birth weights in the study group ranged from 235 to 5790 g, with equal proportions of male and female infants. Six new fetal weight estimation models were compared with the results for modified Hadlock models with sample-specific coefficients. All the new models were very accurate, with mean percent differences that were not significantly different from zero. Model 3 (which used the natural logarithms of BPD, AC and AVol) and Model 6 (which used the natural logarithms of BPD, AC and TVol) provided the most precise weight estimations (random error = 6.6% of actual birth weight) as compared with 8.5% for the best original Hadlock model and 7.6% for a modified Hadlock model using sample-specific coefficients. Model 5 (which used the natural logarithms of AC and TVol) classified an additional 9.1% and 8.3% of the fetuses within 5% and 10% of actual birth weight and Model 6 classified an additional 7.3% and 4.1% of infants within 5% and 10% of actual birth weight.
CONCLUSION: The precision of fetal weight estimation can be improved by adding fractional limb volume measurements to conventional 2D biometry. New models that consider fractional limb volume may offer novel insight into the contribution of soft tissue development to weight estimation.
Copyright (c) 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Sonographic fetal weight estimation in prolonged pregnancy: comparative study of two- and three-dimensional methods
Ultrasound Obstet Gynecol. 2009 Mar;33(3):295-300.
Lindell G, Marsál K. Source Department of Obstetrics and Gynecology, Clinical Sciences, Lund University, Lund, Sweden. email@example.com Abstract OBJECTIVES: To compare two-dimensional (2D) and three-dimensional (3D) ultrasound techniques, including volumetry of fetal thigh, for fetal weight (FW) estimation in prolonged pregnancy, and to develop a new FW estimation formula.
METHODS: This prospective comparative study initially included 176 pregnant women. FW estimation was performed at >or= 287 days of gestation within <or= 4 days of delivery. Fetal head, abdomen and femur were measured using 2D ultrasound techniques, and fetal thigh volume was estimated using 3D techniques. The formula of Persson and Weldner (2D) was compared with two 3D formulae published by Lee and colleagues. In a subgroup of 63 fetuses, volumetry of the abdomen was performed and a new formula was developed; this formula was tested prospectively, along with the previously published formulae, on a further 50 women (Test Group).
RESULTS: In the initial group of 176 pregnancies, the SD of the mean percentage error (MPE) was 6.3% for both the 2D Persson and Weldner formula and for the better performing 3D formula of Lee et al., but the MPE of this Lee formula differed significantly from zero. Significantly more FW estimations were within +/- 10% of the birth weight when the 2D formula was used than when the 3D formulae were applied. The new formula gave a SD of MPE of 5.6% when applied to the data from which it was derived. In the Test Group, the SD of MPE was similar for the 2D formula, the second formula of Lee et al. and the new formula, with values of 7.0, 7.0 and 7.1, respectively, but only the Persson and Weldner formula showed a MPE that did not differ significantly from zero.
CONCLUSIONS: FW in prolonged pregnancies can be estimated using 2D sonography with the same accuracy as with 3D sonography. 3D ultrasound techniques require technically advanced and expensive equipment, special operator training and skills, and are time consuming. It does not seem reasonable to abandon the 2D ultrasound methods in favor of 3D ultrasound imaging for FW estimation.
(c) 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Quantitative standards for fetal and neonatal autopsy
Am J Clin Pathol. 2006 Aug;126(2):256-65.
Archie JG, Collins JS, Lebel RR. Source Office of Epidemiology, Greenwood Genetic Center, Greenwood, SC, USA.
Growth curves are essential for determining whether growth parameters lie within normal ranges. In the case of fetal and neonatal autopsy, relevant data are scattered across many publications, and few sources examine a large enough sample to be considered definitive. To ameliorate these inadequacies, regressions were created incorporating data from multiple sources both to increase accuracy and to condense available data into a single standard. When measurements were not well studied, the best available published standards are given. These regressions provide a valuable tool for clinicians who need to understand the significance of measurements obtained during autopsy.
Supplementary Data http://autopsy.jarchie.com/fetal_growth_curves.pdf
Age terminology during the perinatal period
Pediatrics. 2004 Nov;114(5):1362-4.
Engle WA; American Academy of Pediatrics Committee on Fetus and Newborn.
Consistent definitions to describe the length of gestation and age in neonates are needed to compare neurodevelopmental, medical, and growth outcomes. The purposes of this policy statement are to review conventional definitions of age during the perinatal period and to recommend use of standard terminology including gestational age, postmenstrual age, chronological age, corrected age, adjusted age, and estimated date of delivery.
World Health Organization, Low Birth Weight: A tabulation of available information, WHO/MCH/92.2, World Health Organization, Geneva, and UNICEF, New York, 1992.