Spring is here. Are you doing the right thing to make your child taller?

Spring is here, everything is growing, and parents are looking forward to their children growing taller. Do you know anything about growing taller?

1. Is it true that spring is the peak period for children’s growth?

Indeed, studies have shown that children’s growth is non-uniform and seasonal. Some research results show that children grow faster in the spring, while others show that children grow faster in the summer months [1-2]. The reasons for this are still unclear, but may be related to the cyclical secretion of hormones in the human body [3].

No matter whether they grow faster in spring or in summer, in short, the short-term growth of children's height is irregular. It may be slower in these months and then catch up after a while. Therefore, when evaluating a child's height development, we cannot only look at the short-term height growth rate. We need to monitor continuously and draw a height growth curve to observe the child's growth trend in the long term and regularly.

2. What is a height growth curve? How to read a child’s growth curve?

The horizontal axis is age and the vertical axis is height (body length). Starting from birth, points of the child's height/age are regularly drawn on the coordinate axis. By connecting the points, you can get a growth curve for the child.

As shown in the picture above, the red line is a child’s height growth curve, and the remaining 5 lines are standard curves for comparison.

So how do you determine whether a child's height growth curve is normal? There are two aspects to consider:

1. Vertical comparison: that is, compared with the standard value of children of the same age, if the height is between the P3-P97 curves, it is considered normal, that is, the normal height is between the 3rd and 97th percentiles of the height of children of the same age. Below the P3 curve is short, and above the P97 curve is tall.

2. Horizontal comparison: that is, compare yourself with yourself. If the trend of your curve is basically consistent with the standard curve, and the up and down fluctuations do not cross the two standard curves, it is considered normal. Otherwise, you need to consider whether the growth is too slow or too fast.

Judging from these two standards, although the child in the above growth curve is not tall among children of the same age and is in the 15th percentile, it is normal and not short.

3. To what extent does height have to do with genetics?

Yao Ming is 226cm tall, and his 12-year-old daughter is now almost 190cm tall, showing us the power of genetics. Scientific research has also proven that genetics is the dominant factor in determining height, accounting for about 60-80%, and the remaining 20-40% is determined by environmental factors, the most important of which is nutrition.

Genetics is dominant, so doctors can calculate the child's genetic target height based on the parents' height to preliminarily predict the child's final height in adulthood. There are two calculation methods: CMH method and FPH method.

The formula for the CMH method is:

Boys (cm) = (father's height + mother's height + 13)/2 ± 8.5

Girls (cm) = (father's height + mother's height - 13)/2 ± 8.5

The formula of the FPH method is:

Boy (cm) = 45.99 + 0.78 × (father's height + mother's height) ÷ 2 ± 5.29

Girls (cm) = 37.85 + 0.75 × (father's height + mother's height) ÷ 2 ± 5.29

Of the two methods, the CMH method is simpler to calculate and is commonly used in clinical practice, but recent data show that the FPH method may be more accurate [4].

Using these two methods to calculate the height of Yao Ming's daughter (Yao Ming's height is 226cm, Ye Li's height is 190cm), the results are 201.5±8.5 (cm) and 193.85±5.29 (cm) respectively, which is consistent with the current height of Yao Ming's daughter.

However, although heredity is important, it is not a 100% factor. As NBA stars, Jeremy Lin's parents are both less than 170cm tall, but Jeremy Lin is 192cm tall. Why is this? Don't forget that in addition to heredity, 20-40% of height is determined by environmental factors such as nutrition. We should not easily "give up on ourselves".

4. Is it okay to get a height-increasing injection?

It depends on the situation. Blindly taking the so-called "height-increasing injection" is absolutely not advisable.

Here we need to clarify two questions: 1. What is the height-increasing injection? 2. Under what circumstances can it be used?

What we commonly call "height-increasing injections" refers to the injection of growth hormone. Under normal circumstances, the human body can synthesize growth hormone on its own. It is also an essential hormone in the growth and development process, and has many physiological effects such as promoting the growth of bones and cartilage. If the human body lacks growth hormone, it will show short stature and other symptoms.

Only when it is clear that the dwarfism is caused by growth hormone deficiency, or when the height is absolutely short (shorter than the 3rd percentile), can we promote height growth by supplementing growth hormone. The premise of using growth hormone is that it must be systematically evaluated by a professional doctor.

The doctor will evaluate two aspects: 1. Whether the child meets the diagnosis of short stature: In many cases, the child is not short, but the parents have set too high psychological expectations. Using growth hormone for a child with normal height is definitely not worth the cost;

2. Analyze the cause of short stature: For short stature caused by growth hormone deficiency, injection is recommended. In this case, the height increase effect is often better. For some children, no clear cause can be found, which is called idiopathic short stature. If the height is indeed very short, injection can also be considered after evaluating the risks and benefits of growth hormone injection.

But no matter what the reason, can children grow taller by injecting growth hormone? This is not necessarily the case. If there is no growth hormone deficiency, injecting growth hormone may not necessarily make children grow taller. Even if it is effective, the effect is not that good, and it will only increase the height by about 4-6cm.

In addition to the poor effect, there are also the following problems with growth hormone injections:

1. It is very expensive and the treatment process is difficult, requiring daily injections for several years;

2. Although it is generally safe (but the safety data comes mainly from children with short stature, and there is a lack of data on its safety for children of normal height), there are still certain adverse reactions. For example, growth hormone may cause abnormal growth of bones and internal organs; promote the growth of existing or potential tumors; and may increase the risk of future cardiovascular disease.

Many informal institutions now take advantage of parents' height anxiety and abuse growth hormone, which is undoubtedly extremely irresponsible to children's health. Parents must go to formal medical institutions to fully assess their children's height, and should not use "height-increasing injections" at will or believe in the so-called "customized height".

5. What is the truly reliable “way to increase height”?

Although genetic factors cannot be changed, efforts to change environmental factors that affect height can fully develop children's height potential. Parents are advised to start with the following points:

1. Monitor your child’s growth curve and seek medical attention promptly if any problems are found.

If the curve exceeds the normal range of the 3rd percentile and the 97th percentile, or if the height is still within the normal range but suddenly grows slower or too faster, it is recommended to seek medical attention promptly.

2. Stay healthy and get sick less often.

Daily vaccinations on time, frequent hand washing, more ventilation, less crowded places, correct wearing of masks, etc. can effectively reduce the possibility of children contracting various infectious diseases. In addition, some chronic diseases such as allergic rhinitis and asthma can also affect the height of children. If children have these diseases, they should be actively controlled.

3. Comprehensive and balanced nutrition.

Nutrition is the most important factor affecting height besides genetic factors. We should pay attention to giving children a sufficient and balanced diet. No one kind of food will increase height. Only a comprehensive intake of various nutrients can provide children with the most adequate nutrition. However, we should not have excessive nutrition. If children are obese, it will increase the incidence of precocious puberty and affect their lifelong height in adulthood.

4. Reasonable exercise and adequate sleep.

The relationship between exercise and sleep and height is not clear at present, but reasonable exercise and adequate sleep can promote physical health, reduce disease, prevent obesity, etc., thus playing a positive role in height growth.

5. Psychology: Keeping a happy mood is also of great benefit to children's health and may also promote height growth.

Summarize:

Seven points of a child's height are determined by nature, but the remaining three points are determined by nurture. We should pay attention to providing children with balanced nutrition, proper exercise, adequate sleep and a happy mood.

Parents should pay attention to record and monitor their children's growth curves and seek medical attention promptly if any problems are found;

You should not blindly use growth hormone in the hope of making your child grow taller. It should only be used when necessary after evaluation by a professional doctor.

【References】

Gelander L, Karlberg J, Albertsson-Wikland K. Seasonality in lower leg length velocity in prepubertal children. Acta Paediatr. 1994 Dec;83(12):1249-54.

Narumi S, Ohnuma T, Takehara K, Morisaki N, Urayama KY, Hattori T. Evaluating the seasonality of growth in infants using a mobile phone application. NPJ Digit Med. 2020 Oct 21;3:138.

Tendler A, Bar A, Mendelsohn-Cohen N, Karin O, Korem Kohanim Y, Maimon L, Milo T, Raz M, Mayo A, Tanay A, Alon U. Hormone seasonality in medical records suggests circannual endocrine circuits. Proc Natl Acad Sci US A. 2021 Feb 16;118(7):e2003926118.

Jiang Jing, Fu Manfen, Qiu Dingzhong, et al. Comparison of two methods for predicting genetic lifelong height[J]. Journal of Practical Pediatrics, 2004, 19(11): 980-982.

Patient education: My child is short https://www.uptodate.cn/contents/zh-Hans/my-child-is-short-the-basics (The Basics) - UpToDate

Author: Zhang Lujie

Reviewer: Tang Qin, Director of the Science Popularization Department of the Chinese Medical Association

This article is produced by the Science Popularization China-Creation Cultivation Program. Please indicate the source when reprinting