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1 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds Paper No. : 06 Human Growth Development and Nutrition Module : 13 Catch Up Growths , Maturation, Growth References and Standards Prof. Anup Kumar Kapoor Department of Anthropology, University of Delhi Development Team Principal Investigator Paper Coordinator Content Writer Content Reviewer Dr. Meenal Dhall Department of Anthropology, University of Delhi Ms. Urvashi Gupta and Dr. Meenal Dhall Department of Anthropology, University of Delhi Department of Anthropology, University of Delhi Prof. Satwanti Kapoor Department of Anthropology, University of Delhi 2 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds Description of Module Subject Name Anthropology Paper Name 06 Human Growth Development and Nutrition Module Name/Title Catch Up Growth, Matur ation , Growth References And Standards Module Id 13 3 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds Contents of this unit Introduction Catch - up Growth 2.1 Compensatory Growth 2.2 Canalization 2.3 Catch - up growth in association with Canalization 2.4 Factors affecting catc h - up growth 2.4.1 Malnutrition 2.4.2 Celiac Disease 2.4.3 GH Deficiency 2.4.4 Hypothyroidism 2.4.5

Intra - uterine Growth Retardation 3. Maturation 4. Growth References and Standards References Learning Outcomes  To understand the concept of catch - up growth  To have clear understanding of related topics like canalization and compensatory growth  To know about the factors affecting catch - up growth  To know about growth standards and references 4 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds 1. Introduction According to British Engl ish dictionary, growth refers to the progressive development of a living being or part from an earlier stage to its maturity including increase in size and development as a series of changes by which an individual embryo becomes a mature organism. Many tim es, people use the terms growth and development interchangeably without realizing that these terms actually differ in their meanings. In Biological and Physiological sciences, these terms have slightly differing connotations. Growth refers to increase in s ize of various organs and parts of body by multiplication of cells and intercellular components during a period commencing from fertilization to maturity. Growth is actually a result of three processes – increase in cell number (hyperplasia), increase in c ell size (hypertrophy) and increase in inter - cellular substances (accretion), which underlie maturity and differentiation. Development or maturation is the increase in functional capacity for producing specialized cells from unspecialized ones and complexi ty in skill progression. Therefore, growth is increase in terms of quantity while development in terms of quality. Both are target seeking and dynamic in nature. The end point of growth is size attainment by adulthood at a rate less than 1cm/year. The end point of maturity is the functional ability of an individual t

o procreate and not simply be able to produce viable sperms/ova. Thus, successful maturation requires not just biological but also behavioral and social maturity (Cameron, 2012). Growth remains the chief phase of biological activity up to about 20 years of age, whereby height, weight, body build, etc of a person increase till he reaches his adult age and afterwards sooner or later starts degenerating too, marking the beginning of older/senescenc e age. However, the rate at which these changes take place differ in different stages of growth. For example, during prenatal, neonatal, infancy and adulthood, growth rate increases very rapidly. It slows down during infancy and gets stable during adulthoo d. However, during old age, cells and tissues start degenerating. These processes are highly influenced by both genetic (intrinsic) and environmental (extrinsic) factors including release of endocrine and exocrine hormones, especially growth hormone, genet ic aberrations, Epigenetics , nutrition, season, climate, altitude, socio - economic condition, psychological condition, race and ethnicity. In case, any of these factors are not available or becomes unsuitable, it would hamper the proper growth and developme nt of the individual. Assessment of growth and maturation depends upon various indicators. While dealing with huge data to come up with the outcomes revealing the trends and patterns of growth, it becomes important to have certain reference with which the collected numbers could be related and compared. These standards and references must be universal, sequential, reliable, valid and complete in terms of their characterization of maturity. Considering this, several standards and references are set up at nat ional and international levels allowing the comparison of various groups of people inhabiting different regions of world. 2. Catch - up Growth 5 Anthropology Human Growth Development and Nutrition Ca

tch Up Growth, Maturation , Growth References And Standa rds The term catch - up growth was introduced by A. Prader, J.M. Tanner and G.A. Von Harnack (1963) to describe the incre ased growth velocity which occurs in children after a period of growth retardation when the cause of the growth retardation is removed (Cameron, 2012). It is the growth velocity above the statistical limits of normality for a particular age during a define d period of time, following a transient phase of growth inhibition (Boersma, et al., 1997). After illness or starvation which is a period characterized by slow growth, there has been found tendency in the younger subject’s to bridge the deficit as soon as possible and catch up with the original growth - curve. This is known as catch - up growth. The velocity during initial period of catch - up may reach three times the normal for age. The term compensatory growth is sometimes used by nutritionists to describe a s imilar phenomenon; however, that term was first applied to the quite different phenomenon of the replacement growth of organs or parts thus, showing compensatory growth. Catch - up may be complete or incomplete; if the stress has been severe, and particularl y if it has been applied early in the animal’s life, then even though a catch - up velocity may be established for a while it may be insufficient to return the animal completely to its normal curve of growth (Bose. K). The end point of catch - up growth is to take an organism towards, or in favorable circumstances right onto its original pre - retardation growth curve. In the former case, catch - up growth is said to be incomplete and complete in the latter. 2.1 Compensatory Growth Catch up growth and compensatory gro wth appear to synonymous, but they are not. Compensatory growth is not only used to describe the growth of whole organism but also the overgrowth of a single or part of an organ when another part is removed. For exa

mple regeneration of liver either after i ts partial hepactomy or due to removal of its part for purpose like organ transplantation/donation. Hence, compensatory growth could actually be the effort of an organ or its part to overcome the effect of some functional inadequacy. For achieving this, th e remaining part/cells of the organ undergo the basic processes of growth - hyperplasia, hypertrophy and accretion. In other words, it is a type of growth that occurs mainly after the loss of a mass of cells/tissues or part of an organ itself. Compensatory growth may be viewed as being controlled by a simple feedback mechanism while catch up growth is rapid growth that compensates for the loss of potential tissues and thus can’t be accounted for by a simple feedback mechanism. Mechanism controlling catch - up growth must be able to foresee lack of growth response of a tissue while the mechanism for checking compensatory growth reacts to the permanent loss of a tissue (Boersma et al., 1997). 6 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds Figure1. Catch up growth 2.2 Canalization Canalization is the tend ency of a trait to follow a certain course or trajectory over time. Growth being a dominant biological activity from prenatal phase till the attainment of adulthood, leads to many physical and biological changes in an organism. Rapid growth during infancy which slows down throughout childhood, suddenly increase again at adolescence and puberty, which then finally ceases at adulthood. This cyclic and periodic acceleration and deceleration of growth during different phases needs some mechanism to keep a check on it. Such a controlling system is very dynamic and complex that makes the growing child return to its path of growth after deviation. This tendency to keep to a narrow and predictable track of growth is called canalization. It is

a pre - requisite for cat ch - up growth. If normal growth is not canalized then it would not be possible to recognize the phase of catch - up growth. Canalization is the individual growth curve that parallels the centile curves of growth charts. In the pre - pubertal period, canalizatio n is clearly recognizable, but thereafter its presence becomes less pronounced. Hence, catch - up growth spurt is easily recognizable in the pre - pubertal period, and ther after it is often impossible to discriminate between pubertal growth spurt and catch - up growth acceleration (Boersma, et al., 1997). 7 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds The term canalization was first used by C.H. Waddington in 1957 to describe the pattern of growth in all children that is more or less parallel to a particular centile or with some imaginary canal in an environ ment that does not constrain their growth. It is most likely that this pattern is genetically determined and a target seeking phenomenon whose main aim is to take an individual to the adult stature in an unconstrained environment. 2.3 Catch - up growth in a ssociation with Canalization No child can ever be brought up in a completely unconstrained environment. Even towards the end of our intra - uterine life, our growth was constrained by the size of the uterus. During infancy and childhood, children are all the time vulnerable to various diseases. Diseases which can lead to loss of appetite thus hampering and slowing down the rate of growth or in more severe case may actually cease it. Figure2. Movement of ball down the valley which resembles canalization pro cess in human growth While explaining the concept of canalization and catch - up growth, Waddington compared growth with movement of a ball rolling down a valley. Here, different phases of catch - up growth have been related to d

ifferent points of the ball’s movement.  Movement of the ball down the valley on a central course, is the first phase representing the canalized growth, where the sides of the valley keeps the ball on the right track and helps it to roll steadily. This is point A of the ball’s movement .  In case of an obstacle, the ball tends to move out of its regular path or canal, which pushes the ball to move away from the central path. It represents point B or the second phase in which an insult causes the normal growth to get slow down or changing its actual rate and path.  The amount of deviation from the predefined path depends upon the severity and duration of the insult. Likewise, the velocity of the moving ball depends upon the severity and duration of 8 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds the obstruction coming in its path. When t he obstacle is removed, the ball tends to return to its original path maintaining its initial velocity or it just move with a much faster speed down the valley. This is the point C which resembles the third phase of catch - up growth when the insult is allev iated and the rate of growth resumes its normal speed or gets doubled.  At point D, the ball acquires its earlier path of the valley and so does the growth which resumes its normal canalized path in the last phase of the catch - up growth. 2.4 Factors affect ing catch - up growth It is not in all cases that catch - up growth takes place and resumes the normal growth of a person. In several cases, the severity or duration of the insult is so much that catch - up growth is never able growth to turn up and the growth r ate is never able to return to its original pace, resulting in permanent stunting of growth. Therefore, the harshness and the longevity of the constrained environment drive the movement of catch - up growth. Some

of the cases have been discussed below to exp lain the response of catch - up growth in each of them. 2.4.1 Malnutrition It is the most common cause of stunted growth and under - development. Prolonged malnourishment results in permanent stunting and growth inhibition. However, severity of undernourishmen t results in the faster pace of regaining the growth rate. Whereas, under nutrition in the initial stages of life may have very harmful effects on the growth of a child, leading to slow growth initially and later leading to under - development. 2.4.2 Celiac Disease It is a kind of abnormality in which the gut lining inhibits the absorption of food, resulting in the child being starved. Since it causes malabsorption, growth retardation in the initial stages of growth is witnessed leading to breakdown of normal linear growth and short stature. 2.4.3 GH Deficiency Insufficient production of growth hormone in the body is another one of the common factors responsible for stunted growth and growth retardation, especially in the younger ages. 2.4.4 Hypothyroidism It is associated with growth failure due to decreasing effects of the thyroid hormones on the skeletal growth. It also leads to a secondary reduction in the release of GH. However, it treated properly, at right time; the growth rate can pursue its original ra te ensuring positive catch - up growth. 2.4.5 Intra - uterine growth retardation (IUGR) It is diagnosed when the birth weight or birth length is lower for the gestational age of the infant. Major proportion of children with IUGR tends to attain catch - up growth in the first two years of their life. However, 20 - 30% of IUGR affected children are not able to catch - up at all and remain underdeveloped. The probability of catching up completely depends upon the damaging agent, its timing of occurrence and the duration of damage. 3. Maturation Bogin defines maturation or development as “a progressi

on of changes, either qualitative or quantitative, that lead from an undifferentiated or immature state to a highly organized, specialized and mature state”. The end point of ma turation, within the context of growth, is the attainment of 9 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds adulthood, which is the state of being a functionally mature individual. Functional maturation, in the biological context, implies to the ability to successfully procreate and raise offspring who themselves will successfully procreate. The process of maturation continues throughout life - it begins at conception and ends at death. Thus, growth and maturation are closely related and both must reach functional and structural endpoints for providing th e opportunity of successful procreation (Cameron, 2012). Maturation is not linked to time in a chronological sense. In other words, one year of chronological time is not equivalent to one year of maturational time. Although, each individual has passed thr ough the same chronological time span, but that doesn’t mean that they would have same rates of maturation. Maturation is often assessed by the identification of maturity indicators that are discrete events or stages recognizable within the continuous chan ges that occur during the process of maturation. There is variability of maturation within an individual, meaning that two events are not mutually related or associated. Maturation could be assessed using the following indicators:  Skeletal maturity  Dental maturity  Sexual maturity in terms of development of secondary sexual characteristics among both males and females 4. Growth References and Standards Growth references and standards are essential components in the human growth and development studies. Their v alue resides in helping to determine the degree to which physiological

needs for growth and development are met during the important childhood period. Beyond their usefulness in assessing children's nutritional status, many governmental and United Nations agencies rely on them to measure the general well - being of populations, formulate health and related policies, and plan interventions and monitor their effectiveness. Growth Standards and references describe the standards for constructing following charts - length/height - for - age, weight - for - age, weight - for length, weight - for - height and BMI - for - age. The construction of the child growth curves requires a careful, methodical process. Rigorous methods of data collection and standardization are followed during the entire study. Sound 10 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds Figure3. Symbolic representation of a growth reference chart Procedures for data management and cleaning are applied. As a result, the anthropometric data available for analysis become of the highest possible quality. The selecti on of the best statistical approach to construct the standards follows a broad consultative process (WHO). A growth reference aims to describe the growth pattern in a population. It aims to prescribe what the normal growth pattern should be. In order to pr escribe, it is important that growth standards are based on data from people without known risk of growth faltering. For example: the WHO growth standards excluded not only infants with mortality but also infants whose mothers did not follow recommended br eastfeeding and non - smoking guidelines ( Cheung, Y.B.). A growth reference is a table or chart summarizing how an anthropometric measurement such as height, weight, etc changes during childhood, based on a defined reference sample and the charts consist of selected centiles of the measurement at different ages of childhood. P

urpose of growth reference is to account for age and sex differences in anthropometry. In practice it is used in two contexts: as clinical sign, to monitor the growth status of individua l children, and as a public health tool, to summarize and compare the anthropometry of groups of children. On the other hand, growth standard represents healthy growth, whereas reference makes no claims about the health of its reference samples. Therefore, a standard is better than a reference for diagnosing the growth disorders, always assuming that the standard is appropriate for the child being assessed. In practice reference is easier than a standard to construct, as there is no need to define good grow th, or to exclude individuals from the reference sample who fail to achieve it ( Ulijaszek et al., 1997) . 11 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds Figure4. Growth reference curves for height, weight and head circumference (for preterm infants) Summary The biological phenomenon of Catch - up growth is a strong inherent will and power of a child to resume and maintain its predetermined growth pattern. The Multifactorial nature of catch - up growth is revealed by the fact that not only among different diseases but also among different individuals with t he same disease, variability in following up catch - up growth has been witnessed and supported through various studies conducted in different parts of the world. Apart from nature - nurture (gene - environment) effects on the pattern of catch - up growth among di fferent individuals in different settings, the intensity, duration and, the time and type of insult hampering the growth of individual along with the efficacy of the treatment or therapy provided and the time at which it is being provide (for example, such a treatment would have maximum positive influence on growth pattern if provided

at the initial stage of exposure to the insult, while it would have minimum effect if provided afterwards when there are no further chances of improving the growth) represent the major influencing factors. Maturation, being a progression of changes that lead from an undifferentiated or immature state to a highly organized, specialized and mature state, results in the functional maturity of an individual. In the biological conte xt, it refers to the ability to successfully procreate and raise offspring who themselves will successfully procreate. It is not a strictly time/chronological age dependent process hence, two individuals of the same age may not have the same level of physi cal maturation changes. Moreover, not even two maturation events are synchronized to happen in the same individual. Therefore, there are methods for assessing the level of maturation using certain physical features or indicators - skeletal 12 Anthropology Human Growth Development and Nutrition Catch Up Growth, Maturation , Growth References And Standa rds maturity, dental maturity and sexual maturity in terms of development of secondary sexual characteristics among both males and females. Growth references and standards are essential components in the human growth and development studies. Their significance lies in the fact that they are really very useful in assessing children's nutritional status. Many governmental and United Nations agencies rely on them to measure the general well - being of populations, formulate health and related policies, and plan interventions and mon itor their effectiveness. For constructing following charts - length/height - for - age, weight - for - age, weight - for length, weight - for - height and BMI - for - age, growth references and standards play very important role as they determine the degree to which physiolo gical needs for growth and development are met during the important childhood period