As determinant for foetal growth and that of neonates several classifications are in use. A simple grouping is based on birth weight alone, another correlates gestational age and sex and a third considers the possible failure of reaching the child's growth potential. Here, we briefly explain some of these terms.
There are different ways to categorise and assess growth at birth. One way is solely based on weight and independent of gestational age (Fewtrell et al., 2016):
Another way to categorise growth includes (gestational) age. For foetuses and neonates, the terms small or large for gestational age are used; these correspond to the sex appropriate weight-/ lengths-for-age charts for infants and older children (Mayer & Joseph, 2013).
The terms "large‑for‑gestational age" and "macrosomia" both refer to excessive foetal growth:
Preterm infants are at higher risk to experience intrauterine and/or extrauterine growth retardation or restriction (Koletzko et al., 2014). These terms mean that the child could not reach its intrinsic growth potential, for example, through placental insufficiency and thus an energy or nutrient bottle neck during pregnancy (intrauterine growth retardation) (Mayer & Joseph, 2013, Koletzko et al., 2014). Preterm infants are likely to be born with low, very low, or extremely low birth weight and often are small-for-gestational age. Preterm infants have high energy and nutrient requirements. It is challenging to meet these needs and many preterm infants especially those born very early experience extrauterine growth retardation when those needs cannot be met after birth. Some preterm infants experience extrauterine growth retardation on top of their intrauterine growth retardation. These growth retardations – alone or in combination – are difficult to address and may persist well into the first year(s) of life (Koletzko et al., 2014, ÖGKJ, 2012, Aggett et al., 2006).
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Fewtrell M, Michaelsen KF, van der Beek EM, van Elburg RM, editors. Growth in early life: Growth trajectory and assessment, influencing factors and impact of early nutrition. 1st. Chichester, United Kingdom: John Wiley & Sons, Ltd; 2016. (Essential Knowledge Briefings; vol 3). at: www.essentialknowledgebriefings.com
Koletzko B, Poindexter B, Uauy R, editors. Nutritional care of preterm infants: Scientific basis and practical guidelines. 1st. Basel: Karger; 2014. (World review of nutrition and dietetics; vol 110). at: https://www.karger.com/Book/Toc/261508
Mayer C, Joseph KS. Fetal growth: a review of terms, concepts and issues relevant to obstetrics. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology 2013; 41(2):136–45. at: https://pubmed.ncbi.nlm.nih.gov/22648955
ÖGKJ. Nutrtition of premature infants after discharge; a consensus paper of the Austrian Society for Pediatric and Adolescent Medicine (ÖGKJ): Ernährung Frühgeborener nach der Entlassung. Monatsschrift Kinderheilkunde 2012 [status of: 2020 Nov 18]; 160:491–8. at: https://link.springer.com/article/10.1007/s00112-011-2618-9#citeas
Yehudamalul. Weight vs gestational age: Image CC-BY-SA 3.0 via Wikimedia Commons; 2010 at https://commons.wikimedia.org/wiki/File:Weight_vs_gestational_Age.jpg or https://upload.wikimedia.org/wikipedia/commons/2/2b/Weight_vs_gestational_Age.jpgback