Pediatrics and Neonatology (2015) 56, 79e80
Available online at www.sciencedirect.com
ScienceDirect journal homepage: http://www.pediatr-neonatol.com
EDITORIAL
Small-for-gestational-age in Very-low-birthweight Infants: Good or Bad? Small-for-gestational-age (SGA) is defined by the criterion of birth weight < 10th percentile of reference population at the same gestational age. Some cases are found prenatally, that is due to intrauterine growth restriction. It is unclear why the fetus grows poorly in the uterus. The causes of SGA are multifactorial and comprised of maternal, placental, fetal, and environmental factors. In theory, the newly born SGA infants will be stronger than infants born with a similar weight, because of greater maturity in SGA infants and stimulation under stress in uterus. However, they will be weaker than infants born with a similar gestational age, because of a less friendly growth environment in the uterus. SGA is a heterogeneous disease entity. Whether the SGA is a good or bad prognostic factor among premature infants is still under debate. An annual report from the Premature Baby Foundation of Taiwan in 2011 revealed that SGA was associated with a significantly reduced risk of chronic lung disease when adjusted for birth weight. However, Tsai et al1 found that SGA infants were associated with a higher mortality rate, a higher severe retinopathy of prematurity (ROP), and higher bronchopulmonary dysplasia (BPD). The scientific definition of SGA is important if we want to discuss the prognosis in the perinatal period or the programming effect of SGA in later life. The cutoff of SGA at the 10th centile of the reference population was recommended by the World Health Organization expert committee, but a lower cutoff, such as below the 3rd centile, is supposed to be more relevant to outcome.2,3 Lee et al2 claimed that the burden of babies born SGA is very high in low- and middle-income countries because of a higher prevalence of SGA infants and higher risks for longterm disability and mortality. In a study in rural Nepal,4 it was found that being born preterm had long been associated with high neonatal and infant mortality, but SGA also increased risk consistently throughout infancy. The same study also found that maternal height and body mass index were inversely related with preterm SGA birth. One study conducted from a secondary data analysis of the World
Health Organization Multi-Country Survey on Maternal and Newborn health5 found that the risk of mortality in preterm SGA was higher compared to preterm appropriate-forgestational-age in low to high human development index countries, but not in very high human development index countries. Therefore, the socioeconomic factor may influence the perinatal outcomes. Figueras et al6 stated that combination with the prenatal ultrasound characters, such as cerebroplacental ratio, mean uterine artery pulsatility index, and estimated fetal weight, could predict adverse outcomes of SGA. Aucott et al7 stated that infants born prematurely who also exhibited severe intrauterine growth restriction had higher neonatal morbidity and mortality when compared to infants of similar gestational age. In the study by Tsai et al,1 SGA also had significant effects on mortality in very low birth weight infants with a gestational age of 24e29 weeks. It could be the severity, extent, timing, or etiology of SGA which made the major contribution to perinatal morbidity and mortality. BPD is a disease of prematurity. The pathogenesis is also multifactorial, including prematurity, patent ductus arteriosus, vascular maldevelopment, arrested sacular and alveoli development, mechanical ventilator and oxygen use, genetic background, nutrition status, intrauterine or extrauterine infection, or inflammation. All of these can share the same etiology with SGA. Therefore, the relation between BPD and SGA is only an association, but not a causal relationship. The concept is the same as the relation between ROP and SGA. There are more interesting issues about how SGA infants grow and how the SGA infants progress to metabolic syndrome in later life. Beyond survival, the future of infants with SGA deserves more attention.8 Infants born with SGA are the result of uterine malfunction. It is important to take socioeconomic status and the etiology of SGA into consideration when discussing the perinatal outcomes among preterm SGA infants.
http://dx.doi.org/10.1016/j.pedneo.2015.01.002 1875-9572/Copyright ª 2015, Taiwan Pediatric Association. Published by Elsevier Taiwan LLC. All rights reserved.
80
Editorial
Conflicts of interest 3.
The author declares no conflicts of interest. Hung-Chieh Chou* Department of Pediatrics, National Taiwan University Hospital, National Taiwan University, Medical College, Taipei, Taiwan * Department of Pediatrics, National Taiwan University Hospital, Number 8, Chung-Shan South Road, Taipei 100, Taiwan. E-mail address: [email protected] Jan 14, 2015
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References 1. Tsai LY, Chen YL, Tsou KI, Mu SC, for the Taiwan Premature Infant Developmental Collaborative Study Group. The impact of small-for-gestational-age on neonatal outcome among verylow-birth-weight infants. Pediatr Neonatol 2015;56:101e7. 2. Lee AC, Katz J, Blencowe H, Cousens S, Kozuki N, Vogel JP, et al. National and regional estimates of term and preterm babies born small for gestational age in 138 low-income and
7.
8.
middle-income countries in 2010. The Lancet Global Health 2013;1:e26e36. Santos IS, Barros AJ, Matijasevich A, Zanini R, Chrestani Cesar MA, Camargo-Figuera FA, et al. Cohort profile update: 2004 Pelotas (Brazil) Birth Cohort Study. Body composition, mental health and genetic assessment at the 6 years follow-up. Int J Epidemiol 2014;43:1437e1437aef. Kozuki N, Katz J, LeClerq SC, Khatry SK, West Jr KP, Christian P. Risk factors and neonatal/infant mortality risk of small-forgestational-age and preterm birth in rural Nepal. J Matern Fetal Neonatal Med 2014:1e7. Ota E, Ganchimeg T, Morisaki N, Vogel JP, Pileggi C, OrtizPanozo E, et al. Risk factors and adverse perinatal outcomes among term and preterm infants born small-for-gestationalage: secondary analyses of the WHO Multi-Country Survey on Maternal and Newborn Health. PloS One 2014;9:e105155. Figueras F, Savchev S, Triunfo S, Crovetto F, Gratacos E. An integrated model with classification criteria to predict smallfor-gestational-age fetuses at risk of adverse perinatal outcome. Ultrasound Obstet Gynecol 2014. http://dx.doi.org/ 10.1002/uog.14714. Aucott SW, Donohue PK, Northington FJ. Increased morbidity in severe early intrauterine growth restriction. J Perinatol 2004; 24:435e40. Lawn JE, Blencowe H, Oza S, You D, Lee AC, Waiswa P, et al. Every newborn: progress, priorities, and potential beyond survival. Lancet 2014;384:189e205.
Available online at www.sciencedirect.com
ScienceDirect journal homepage: http://www.pediatr-neonatol.com
EDITORIAL
Small-for-gestational-age in Very-low-birthweight Infants: Good or Bad? Small-for-gestational-age (SGA) is defined by the criterion of birth weight < 10th percentile of reference population at the same gestational age. Some cases are found prenatally, that is due to intrauterine growth restriction. It is unclear why the fetus grows poorly in the uterus. The causes of SGA are multifactorial and comprised of maternal, placental, fetal, and environmental factors. In theory, the newly born SGA infants will be stronger than infants born with a similar weight, because of greater maturity in SGA infants and stimulation under stress in uterus. However, they will be weaker than infants born with a similar gestational age, because of a less friendly growth environment in the uterus. SGA is a heterogeneous disease entity. Whether the SGA is a good or bad prognostic factor among premature infants is still under debate. An annual report from the Premature Baby Foundation of Taiwan in 2011 revealed that SGA was associated with a significantly reduced risk of chronic lung disease when adjusted for birth weight. However, Tsai et al1 found that SGA infants were associated with a higher mortality rate, a higher severe retinopathy of prematurity (ROP), and higher bronchopulmonary dysplasia (BPD). The scientific definition of SGA is important if we want to discuss the prognosis in the perinatal period or the programming effect of SGA in later life. The cutoff of SGA at the 10th centile of the reference population was recommended by the World Health Organization expert committee, but a lower cutoff, such as below the 3rd centile, is supposed to be more relevant to outcome.2,3 Lee et al2 claimed that the burden of babies born SGA is very high in low- and middle-income countries because of a higher prevalence of SGA infants and higher risks for longterm disability and mortality. In a study in rural Nepal,4 it was found that being born preterm had long been associated with high neonatal and infant mortality, but SGA also increased risk consistently throughout infancy. The same study also found that maternal height and body mass index were inversely related with preterm SGA birth. One study conducted from a secondary data analysis of the World
Health Organization Multi-Country Survey on Maternal and Newborn health5 found that the risk of mortality in preterm SGA was higher compared to preterm appropriate-forgestational-age in low to high human development index countries, but not in very high human development index countries. Therefore, the socioeconomic factor may influence the perinatal outcomes. Figueras et al6 stated that combination with the prenatal ultrasound characters, such as cerebroplacental ratio, mean uterine artery pulsatility index, and estimated fetal weight, could predict adverse outcomes of SGA. Aucott et al7 stated that infants born prematurely who also exhibited severe intrauterine growth restriction had higher neonatal morbidity and mortality when compared to infants of similar gestational age. In the study by Tsai et al,1 SGA also had significant effects on mortality in very low birth weight infants with a gestational age of 24e29 weeks. It could be the severity, extent, timing, or etiology of SGA which made the major contribution to perinatal morbidity and mortality. BPD is a disease of prematurity. The pathogenesis is also multifactorial, including prematurity, patent ductus arteriosus, vascular maldevelopment, arrested sacular and alveoli development, mechanical ventilator and oxygen use, genetic background, nutrition status, intrauterine or extrauterine infection, or inflammation. All of these can share the same etiology with SGA. Therefore, the relation between BPD and SGA is only an association, but not a causal relationship. The concept is the same as the relation between ROP and SGA. There are more interesting issues about how SGA infants grow and how the SGA infants progress to metabolic syndrome in later life. Beyond survival, the future of infants with SGA deserves more attention.8 Infants born with SGA are the result of uterine malfunction. It is important to take socioeconomic status and the etiology of SGA into consideration when discussing the perinatal outcomes among preterm SGA infants.
http://dx.doi.org/10.1016/j.pedneo.2015.01.002 1875-9572/Copyright ª 2015, Taiwan Pediatric Association. Published by Elsevier Taiwan LLC. All rights reserved.
80
Editorial
Conflicts of interest 3.
The author declares no conflicts of interest. Hung-Chieh Chou* Department of Pediatrics, National Taiwan University Hospital, National Taiwan University, Medical College, Taipei, Taiwan * Department of Pediatrics, National Taiwan University Hospital, Number 8, Chung-Shan South Road, Taipei 100, Taiwan. E-mail address: [email protected] Jan 14, 2015
4.
5.
6.
References 1. Tsai LY, Chen YL, Tsou KI, Mu SC, for the Taiwan Premature Infant Developmental Collaborative Study Group. The impact of small-for-gestational-age on neonatal outcome among verylow-birth-weight infants. Pediatr Neonatol 2015;56:101e7. 2. Lee AC, Katz J, Blencowe H, Cousens S, Kozuki N, Vogel JP, et al. National and regional estimates of term and preterm babies born small for gestational age in 138 low-income and
7.
8.
middle-income countries in 2010. The Lancet Global Health 2013;1:e26e36. Santos IS, Barros AJ, Matijasevich A, Zanini R, Chrestani Cesar MA, Camargo-Figuera FA, et al. Cohort profile update: 2004 Pelotas (Brazil) Birth Cohort Study. Body composition, mental health and genetic assessment at the 6 years follow-up. Int J Epidemiol 2014;43:1437e1437aef. Kozuki N, Katz J, LeClerq SC, Khatry SK, West Jr KP, Christian P. Risk factors and neonatal/infant mortality risk of small-forgestational-age and preterm birth in rural Nepal. J Matern Fetal Neonatal Med 2014:1e7. Ota E, Ganchimeg T, Morisaki N, Vogel JP, Pileggi C, OrtizPanozo E, et al. Risk factors and adverse perinatal outcomes among term and preterm infants born small-for-gestationalage: secondary analyses of the WHO Multi-Country Survey on Maternal and Newborn Health. PloS One 2014;9:e105155. Figueras F, Savchev S, Triunfo S, Crovetto F, Gratacos E. An integrated model with classification criteria to predict smallfor-gestational-age fetuses at risk of adverse perinatal outcome. Ultrasound Obstet Gynecol 2014. http://dx.doi.org/ 10.1002/uog.14714. Aucott SW, Donohue PK, Northington FJ. Increased morbidity in severe early intrauterine growth restriction. J Perinatol 2004; 24:435e40. Lawn JE, Blencowe H, Oza S, You D, Lee AC, Waiswa P, et al. Every newborn: progress, priorities, and potential beyond survival. Lancet 2014;384:189e205.
