Stages of Growth

It may feel like your baby’s growth accelerates every month—but he actually had the biggest growth spurt of his life in your belly. In nine months, your baby went from a height of 0 inches to his birth height, which is generally around 18 to 22 inches. That rate of height growth is generally never experienced again.

All people go through the following stages:

• Fetal growth – During this stage, insulin plays a central role in growth.
• Childhood growth – Children grow at a rate of about two inches a year up until they are eight years old. In childhood, boys and girls grow at similar rates. During this stage, nutrition plays a central role in the amount and speed of growth.

• Puberty – Children undergo a growth spurt, with boys growing more rapidly than girls. Regulating factors of puberty include:
  • Growth hormone (secreted from the pituitary gland)
  • The sex hormones estrogen and testosterone (which aid bone formation and activate growth hormone)

• Adult height and growth plate fusion – A great percentile of girls reach their adult height at 15, while most boys reach their full height at 17 or 18. While some growth may occur over the next few years, the majority of a person’s height growth is finished by these age ranges.

Until your child has reached the adult phase, his height is not set in stone but determined by a variety of factors.

Factors that Affect Height

How tall will your child be? Some online child height projection tools take just two factors into account to predict your child’s height: the mother’s height and the father’s height. But if you have siblings, you know it’s more complicated than that: two sisters can have very different heights.

Human height depends on many factors, including:

• Genetics
• Nutrition
• Exposure to disease

Genetics vs Nutrition vs Disease: Which factor matters most?

Determining a child’s eventual adult height can be summarized as follows:

• Genetics set the boundary for how tall a child can be.
• Proper nutrition helps the child realize their potential height.
• Disease and environmental factors can hinder their growth pattern.

Therefore, as long as the child grows up healthy (with regards to diet and disease), their adult height can be determined through genetics.

Role of Genetics in Height Prediction

Molecular biologist Chao-Qiang Lai explains in Scientific American that in European populations, height seems to be about 80% hereditary. In contrast, in Asian countries, a child’s future height may be only 65% hereditary—meaning that diet, disease exposure, and other factors can play a greater role in a child’s growth pattern and eventual adult height for different populations.

This difference in heritability is due to generational environmental effects. “When a given environment maximizes the genetic potential of a population for a given trait, this population tends to have a higher heritability for that trait, and vice versa.” So, countries that have offered strong nutritional environments for generations have increased the heritability of height. However, despite the differences between populations, genetics are still the largest factor of adult height in all people.

These genes aren’t all summed up in “tall” or “short” genes. Similar to traits like hair color and eye color, your child’s future height is polygenic—that is, a number of different genes play a role in determining height. In fact, there are as many as 3,290 gene variants that affect height.

Researchers in Nature found that, of 21 studied chromosomal loci, 13 contained “a known skeletal growth gene.” The most well-studied genes involved in height regulate the activity at cartridge growth plates. These areas at the end of bones grow new bone, effectively adding length to a leg or arm bone (and thus increasing height).

Examples of important genes that influence height include:

• GDF5 – The “growth differentiation factor 5” gene helps regulate the child’s normal growth of cells and tissues, including bone and cartilage

• IHH – This gene encodes a protein involved in bone growth
• While many genes are involved in determining height, none has a huge effect on its own.

While many genes are involved in determining height, none has a huge effect on its own. Researchers Brian McAvoy and Peter Visscher found that “The DNA variant with the largest effect on height only has an impact of about five millimetres, and most of the other variants have a much smaller effect.”

5 mm or 0.19 inches hardly affects whether your child is tall enough to be the first pick at volleyball. Instead, height is the result of the complex interactions of the many genes that regulate the proteins and hormones involved in child growth.

Nutrition

Did your mother ever tell you that you had to drink milk to grow up tall and strong? While milk is not the only possible source of the nutrients, she may have been onto something. At a population-wide level, better nutrition is associated with increased future height.

Nutrition is also a key factor in helping your kid maintain a healthy weight and lifestyle.

When it comes to nutrition for growth, all the basics you’ve been taught about diet apply. To reach their full potential height, your child needs:

• Fresh fruits and vegetables
• Adequate protein
• Calcium
• Other vitamins that support bone growth, including vitamins D and K
• Iron

Exposure to Disease; Access to Medication

Researchers Carlos Bozzoli, Angus Deaton, and Climent Quintata-Domeque share that wealthier, healthier populations are statistically taller. By plotting infant mortality vs. adult height, they find that nations where children are exposed to more health risks have shorter populations. Based on this research,

“The early-life burden of undernutrition and disease not only is responsible for mortality in childhood but also leaves a residue of long-term health risks for survivors, risks that express themselves in adult height and in late-life disease.”

Giving additional credence to these findings, researchers Albertine Berard and Martin Blaser found that children who face less exposure to microbes during their developmental period grow up to be taller adults. These researchers suggest that the availability of antibiotics that kill off microbes help children to reach their maximum potential adult height.

While some medications (i.e., antibiotics) may aid in children’s growth, childhood exposure to other medications may impede it. There is a body of research suggesting certain ADHD medications are tied to shorter stature, for example.

A General Prediction of Child’s Height

If you are really curious to get an estimated height prediction of your child with some simple math, follow these steps from the mid-parental height calculator method:

• Step 1: Add both parent’s heights together in inches or centimeters.
• Step 2: On top of the total combined parental height, add an extra 5 inches or 13 centimeters if it’s a boy and subtract if it’s a girl. If you’re pregnant and don’t know your child’s gender yet, see if you’re eligible to take our Gender Prediction Test with our eligibility calculator
• Step 3: Divide the net total by 2 to get the predicted height of your child.

This calculation will give you a rough estimate of your child’s average height when they are fully grown. Although there is no confidence that this is accurate, you can assume that your child’s height will be around one standard deviation away from the predicted average (which is 5 inches taller or shorter than the calculated estimate).

The SneakPeek Early Gender Blood Test

Questions like “ When does baby hair texture change? ” or “ Will my baby’s eyes stay blue ?” are actually very normal questions to have about a baby. As a parent, it’s natural to want to know everything you can about your growing child. You’ll love them whether their hair changes texture or their eyes change color. But the more you know about your baby, the better you can care for them and prepare your family for the future. 

If you are still in the early stages of pregnancy, check out our SneakPeek At-Home Early Gender Blood Test—the only at-home fetal sex test to tell you whether you’re having a boy or a girl as early as 6 weeks into pregnancy. 

Find answers and more today with SneakPeek Test!