Growth charts and reference standards are constructed from the measurements of children who are growing within the normal range or close to it. There is enormous interindividual variation in growth and recognition of normal patterns of growth, so recognizing true deviations can be challenging. When a growth chart demonstrates an apparently abnormal pattern of growth it is important to be able to recognize easily that something is wrong. Before puberty, and after the postnatal period of ex- utero adjustment, most children grow fairly steadily within one centile bandwidth. So much so that any deviation, up or down, may be considered as an indication of potential abnormality, especially if the child is tall or short for their target mid- parental height.
Growth Assessment During Puberty
The unpredictability of the onset of puberty and its subsequent pattern makes the development and presentation of a way of accurately assessing growth during puberty difficult. Current growth charts only represent the average amount of growth taking place for average children going through puberty at the average time, consequently, and paradoxically the charts do not represent the growth curve of any individual child or the wide variation in the timing and the intensity of growth spurt during puberty. The UK 2– 18 year and 2– 20- year charts have, for the first time, begun to address the issue of assessing pubertal growth.
Puberty Growth charts
There have been several attempts to be able to design growth charts to allow for pubertal growth variations. There are four challenges that need to be met:
1. Age at the onset of puberty
2. The proportion of growth completed at the onset of puberty
3. The distance from target or genetic height
4. The pace of puberty
Additionally, the assessment of the degree of development during puberty either using Tanner stages or puberty phases has always been regarded as a separate assessment. The RCPCH UK charts for school age children and the Childhood and Puberty Close Monitoring specialist charts have attempted to combine these assessment by firstly depicting the normal ranges for beginning and completing puberty with vertical puberty lines creating zones on the growth chart to help interpret the appropriateness of growth (Figure 1). As in most cases, normally developing and growing adolescents will not cause concern. It is those that are at the extremes, the tall and advanced in maturing and the short and delayed in puberty who require some form of judgement as to whether their pattern of growth is acceptable. As a result of which additional lines at the extremes, 0.4th centile and 99.6th centile have been added which depict the upper ranges of normal growth, i.e. 99.6th centile for those adolescents who have completed puberty and a lower 0.4th centile for those adolescents who have not yet entered into puberty (Figure 2). Thus, for any young person whose height and weight plots within those ranges, consideration needs to be given as to what has happened to puberty and whether this is indeed normal; this may help to differentiate between path ology and normal variation. However, it is important to note that if a child’s height falls within the shaded zone then their growth could still be abnormal if the child’s height is below their target mid- parental centile range.
Fig1. Puberty zones: vertical puberty lines depict the normal ranges for beginning and completing puberty. The shaded puberty zone marks area where 0.4th centile varies with phase of puberty. Heights in the shaded area below the 0.4th centile mark: (1) Prepuberty: If within two centiles of mid- parental height = within the normal range; and (2) in or completing puberty = below normal range. Reproduced with kind permission from RCPCH and Harlow Printing Limited. Copyright 2019 © Royal College of Paediatrics and Child Health.
Fig2. Lower 0.4th centile for prepuberty phase only. Children whose height lies within the shaded area may be normal if they are not short for their family. Puberty lines mark boundaries of normal pubertal development. Shaded zone marks area where 0.4th centile varies with phase of puberty. Reproduced with kind permission from RCPCH and Harlow Printing Limited. Copyright 2019 © Royal College of Paediatrics and Child Health.
Syndrome- Specific Growth charts
For children with recognized growth conditions there are a number of specialist growth charts available for children with Downs, Turner, Prader– Willi, Williams syndromes, and achondroplasia. These reference charts confer the advantage of being able to see whether a child is growing adequately, not only in com parison to the usual pattern of growth, but also with that particular diagnosis as children with these named conditions grow differently to the population. It also allows recognition of whether an intervention to ameliorate growth has had a significant effect compared with the spontaneous trajectory. They are also useful for reassurance of parents that their child is growing appropriately for their condition.
