Posts

World Health Organization Development Study Results: Gross Motor Milestones In the First Year

 

The line between typical and atypical development can be a hazy one. There are standards that pediatricians, physical therapists, and developmental experts use to monitor growth and deviations from the norm, which allow us to recommend interventions when appropriate.  In 2006, the World Health Organization (WHO) released a whole new set of standards for evaluating and assessing the development of children from birth to 5 years.

What makes this new standard a great tool to monitor the change and growth of infants? This standard is based on data collected from healthy children, over multiple years, in six diverse geographic regions including Southeast and Southwest Asia, Europe, West Africa, North and South America. What is exciting about the new evaluation tool is that now, pediatric specialists have more than just reference curves for physical growth, but curves for motor development as well.

The six gross motor milestones WHO examined in babies were the following:

1.    Sitting without support
2.    Standing with assistance
3.    Hands-and-knees crawling
4.    Walking with assistance
5.    Standing alone
6.    Walking alone

The “windows of milestone achievement” were organized into percentile rankings which pediatricians and physical therapists can use, much like a growth chart.

Without delving too deep into statistics and calculations, the typical age range (in months) for each milestone is listed below:

1.    Sitting without support: 3.8 – 9.2 months
2.    Standing with assistance: 4.8 – 11.4 months
3.    Hands-and-knees crawling: 5.2 – 13.5 months
4.    Walking with assistance: 5.9 – 13.7 months
5.    Standing alone: 6.9 – 16.9 months
6.    Walking alone: 8.2 – 17.6 months

The average (mean) age for healthy children achieving each milestones is as follows:

1.    Sitting without support: 6 months (with 1.1 month standard deviation, SD)
2.    Standing with assistance: 7.6 months (with 1.4 month SD)
3.    Hands-and-knees crawling: 8.5 months (with 1.7 month SD)
4.    Walking with assistance: 9.2 months (with 1.5 month SD)
5.    Standing alone: 11 months (with 1.9 month SD)
6.    Walking alone: 12.1 months (with 1.8 month standard deviation)

(Click here to view this information in chart form from WHO.)

What is most interesting is that about 90% of the children studied met their milestones in a common sequence, and only 4% of the children skipped hands-and-knees crawling.  (Read here about the importance of crawling.)

As you read over these standards and timelines, remember that every baby develops differently from another. If you see your baby fall behind on any of the 6 gross motor milestones above, mention it to his pediatrician, and she will most likely recommend a physical therapist to help him along.



Reference:
WHO Multicentre Growth Reference Study Group.  WHO Motor Development Study: Windows of achievement for six gross motor development milestones. Acta Paediatrica, 2006; Suppl 450: 86-95.

Important Gross Motor Milestone: Jumping

Sometime between the 18th and 24th month, children start learning to jump. Eager parents often ask when to expect their child to jump with both feet off the ground. The simple answer is, every child is different. Of course, we as physical therapists and developmental experts will become concerned if a child is still making no attempts to jump by 2.5 to 3 years. However, what parents should know is that there are many reasons a child could be delayed on a particular gross motor milestone.

Usually, after 6 months of walking independently and participating in typical play (such as climbing on/off furniture, walking up and down stairs with help, and running on various surfaces) a child will have developed the strength and balance needed to jump without falling. When she first starts jumping, she might push off with one foot only and jump down from a low step without help.  By 2 years, a typically developing child can most likely jump forward 3-4 inches while maintaining her balance, with both feet.  She should also be able to bend her knees, with feet together, and propel herself upwards to try to touch something up high.

When to seek physical therapy interventions:

Around 2.5 years of age, if your child continues to show difficulty with jumping and shows any of the following, it is best to bring her into physical therapy so we can check out her alignment, strength and balance, and give her strengthening exercises as needed.

  • Asymmetrical jumping: A typically developing child does not show side-preference until preschool age. If you notice your child always pushing off and landing with one side, seems to drag one side or hold it stiffly, or if one side barely participates in the initiation of jumping, it’s good to mention it to your doctor at her 24 months check-up.
  • No power during push-off: If your child prepares to jump by initiating a squat but then her feet barely leave the floor, her leg muscles may not be strong enough yet to fully propel her weight forwards or upwards.  Or, she might not know how to best coordinate the beginning and end of the activity. If she prefers to step off a low surface or step over an obstacle instead of jumping, she is showing weakness in her legs, especially her thigh and hip muscles.
  • Frequent falls: If she crumbles to the floor or if her knees buckle every time she lands from a jump, or if she falls on purpose when trying to jump, your child may be showing that her body is just not ready for this milestone.
  • Increased anxiety or behavioral resistance to the task: Does your 3 year old hesitate with apprehension, ask to be picked up, or ask for a hand any time she’s encouraged to jump down or over something on the ground? Does she throw a tantrum or flops to the ground if you don’t help her?

All of the above could mean something is keeping a child from jumping. There could be a visual discrepancy or a depth perception issue that can be addressed with occupational therapy, an anxiety/comfort matter that can be addressed by social work, or a deeper issue that can only be attended to after a thorough evaluation by a developmental expert.