Pregnancy

Growth terminology

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.

Growth by birth weight


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):

  • The low birth weight(LBW) group is comprised of both term and preterm infants weighing less than 2500 gram at birth. The low birth weight cut-off corresponds to the 10th percentile of growth charts for healthy boys and girls at 37 weeks gestation (Mayer & Joseph, 2013).
  • Infants weighing less than 1500 gram at birth are considered very low birth weight (VLBW) and
  • those weighing 1000 gram at birth are considered extremely low birth weight (ELBW). Very low birth weight or extremely low birth weight infants are almost always born prematurely.

Growth by weight and gestational age


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 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 restriction) (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 restriction when those needs cannot be met after birth. Some preterm infants experience extrauterine growth restriction on top of their intrauterine growth restriction. 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​​​​​​​).

Bibliography


  • References


    Aggett PJ, Agostoni C, Axelsson I, Curtis M de, Goulet O, Hernell O, Koletzko B, Lafeber HN, Michaelsen KF, Puntis JWL, Rigo J, Shamir R, Szajewska H, Turck D, Weaver LT. Feeding preterm infants after hospital discharge: a commentary by the ESPGHAN Committee on Nutrition. Journal of pediatric gastroenterology and nutrition 2006; 42(5):596–603. at: https://pubmed.ncbi.nlm.nih.gov/16707992

    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: CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons [Gestational age and birth weight of infants born at 24 to 46 weeks' gestation. Infants are classified as large for gestational age (LGA), appropriate for gestational age (AGA), or small for gestational age (SGA). Another classification which takes in consideration only the weight and not the gestational age, is low body weight (LBW), VLBW and ELBW.]; 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.jpg

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