7.6: Motor Milestones

Motor Milestones

Infants and toddlers are constantly learning about the world as they experience it and actively engage with it during the first three years of life. Milestones represent what most children (75% or more) can do by specific ages. This chart represents the new and improved milestone charts provided by the CDC in 2022 with substantial evidence-based updates. These milestone charts are meant to prompt surveillance and conversation and, if needed, identification and early intervention. The CDC adopts a proactive stance—we should take action early when developmental concerns arise rather than the perspective of waiting to see if a child “catches up”. While children do develop at individual paces, being proactive during these critical early years is essential (Morgan et al., 2021; Noritz et al., 2013). The chart below lists milestones that, if children are not achieving by specific ages, caregivers should encourage parents to communicate with their family’s pediatrician. Most caregivers are not professionally trained to officially assess the developmental abilities of children; however, caregivers have the ability to track developmental progress and are often the first to notice developmental concerns. Here is a table of some of the motor milestones for infants and toddlers.

Definition: Milestones

 Represent the developmental abilities most children (75% or more) can do by specific ages

Motor Milestones

Age	What Most Children Can Do By Each Age ^[3]
2 months	● Hold their head up when on their tummy. ● Move both arms and both legs. ● Open hands briefly.
4 months	● Hold their head steady without support while being held. ● Hold a toy when placed in their hand. ● Use their arms to swing at toys. ● Bring their hands to their mouth. ● Push up onto their elbows/forearms when on their tummy.
6 months	● Roll from tummy to back. ● Push up with straight arms when on their tummy. ● Lean on their hands for support when sitting.
9 months	● Stand while holding on for support. ● Can get into a sitting position. ● Sit without support. ● Pull up into a standing position. ● Crawl.
12 months	● Pull up to stand. ● Walk, holding on to furniture. ● Drink from a cup without a lid, as you hold it. ● Pick things up between thumb and pointer finger, like small bits of food.
15 months	● Take a few steps independently. ● Use fingers to feed themselves some food.
18 months	● Walk without holding on to anyone or anything. ● Scribble. ● Drink from a cup without a lid and may spill sometimes. ● Feed themselves with their fingers. ● Try to use a spoon. ● Climb on and off a couch or chair without help.
24 months	● Kick a ball. ● Run. ● Walk (not climb) up a few stairs with or without help. ● Eat with a spoon.
30 months	● Use their hands to twist things, like turning door knobs or unscrewing lids. ● Take some clothes off independently, like loose pants or an open jacket. ● Jump off the ground with both feet. ● Turn book pages, one at a time, when you read with them.
36 months	● String items together, like large beads or macaroni. ● Put on some clothes independently, like loose pants or a jacket. ● Use a fork.

Motor Development Concerns

The motor milestones from the CDC are based on data from infants and toddlers in the U.S., which may not accurately represent the motor development of children from other countries (Karasik, Tamis-LeMonda, Adolph & Bornstein, 2015). Figure 6.6.2 is based on research conducted by the World Health Organization (WHO Multicentre Growth Reference Study Group, & de Onis, 2006). It presents windows of achievement for six gross motor development milestones based on infants and toddlers from five countries: Ghana, India, Norway, Oman and the USA. The six milestones in the chart are sitting without support, standing with assistance, hand and knees crawling, walking with assistance, standing alone and walking alone.

Figure \(\PageIndex{2}\): Windows of achievement for six gross motor milestones. The chart is based on research conducted by the World Health Organization (WHO Multicentre Growth Reference Study Group, & de Onis, 2006). It presents windows of achievement for six gross motor development milestones based on infants and toddlers from five countries: Ghana, India, Norway, Oman and the USA. The six milestones in the chart are sitting without support, standing with assistance, hand and knees crawling, walking with assistance, standing alone and walking alone. (^[4])

Based on the research, there are a few findings worth noting:

• In general, there is a common order in achieving these milestones. First children are able to sit without support, then achieve standing with assistance, followed by walking with assistance which then leads to standing alone and lastly walking alone.
• The one milestone that did not always follow the general order was hand-and-knees crawling. Sometimes children would crawl on their hands and knees before being able to stand with assistance.
• 4.3% of infants did not exhibit hand-and-knees crawling at all—they skipped this milestone and went straight into walking.
• The windows of achievement overlap—Figure \(\PageIndex{2}\) clearly depicts this. The start of each window of achievement for every milestone does not begin near the end of the previous milestone window, but rather begins near the beginning of the previous milestone window. This overlap acknowledges the wide age variability of infants and toddlers achieving these milestones.
• The length of each milestone window varies across the motor skills. Walking alone and standing alone have the longest achievement window, suggesting that these two abilities have the most variability in age of achievement. For example, some children began walking alone around eight months of age, while others did not achieve this milestone until after seventeen months of age. On the other hand, sitting without support and standing with assistance showed the two most narrow windows of achievement, suggesting that these two abilities have the least variability in age of achievement.

Motor Milestone Chart Limitations

Gross motor milestone charts, while important, do not capture the complex developments that lead up to achieving specific milestones. Take for example the process to be able to sit independently. The ability to maintain balance in the sitting posture gradually emerges between 2 and 9 months of age (Butler et al., 2010). When infants are 5 to 6 months old, they are able to ‘prop sit’ or sit independently for short periods (Shumway-Cook & Woollacott, 2003). At 6 months, hip joint mobility increases, allowing the thighs to rest on the contact surface and the infant is able to sit with their legs in a ring position (Bly, 1994), i.e., symmetrically flexed, abducted with externally rotated hips and flexed knees. Between 8 to 9 months, the trunk and pelvis muscles stabilize the sitting position, allowing the infant to narrow the support base for balanced independent sitting (Harbourne, Lobo, Karst & Galloway, 2013; van der Fits et al., 1999). After being able to sit independently, infants learn to perform a coordinated action between upper limbs, trunk and lower limbs as they are able to use their lower body to balance as they reach with their upper limbs (Rochat & Goubet, 1995). Thus, unlike milestone charts that simply show sitting to occur, sitting without support is a process that takes place over many months and involves a complex interplay between various muscles that prepare for the eventual achievement of sitting. ^[5]

Figure \(\PageIndex{3}\): New Skills. (^[6])

Another limitation of motor milestones is that they convey the idea that once an infant performs a motor milestone, like walking, that the infant has fully achieved this milestone. The reality is that motor development involves numerous bouts of successes and failures with each milestone ability. An infant that successfully walks once, may fall the very next attempt. Karen Adolph and her colleagues (2012) have documented the number of steps and falls toddlers have as they learn to walk. Toddlers between 12 to 18 months of age take an average of 2,368 steps in just one hour and cover a distance of 701 meters—the length of almost eight football fields! This is just one hour; multiplying these numbers by the total number of hours toddlers are awake is even more eye-opening. In six hours, a toddler could accumulate around 14,000 total steps and cover the distance of 46 football fields! Despite these infants clearly being able to walk, they also continue to fall. In fact, the average toddler fell seventeen times each hour, one toddler even fell sixty-nine times in one hour.

Figure \(\PageIndex{4}\): Learning to Walk (^[7])

Every day, infants are practicing various motor skills and body positions. For example, Figure \(\PageIndex{5}\) provides insight into the various motor behaviors and body positions from one 10 month old infant. While the majority of time was spent in a seated position (40.5%), the infant was consistently practicing various other positions, frequently rotating between them.

Figure \(\PageIndex{5}\): Frequency of body positions during one day from one 10-month-old infant. provides insight into the various motor behaviors and body positions from one 10 month old infant. While the majority of time was spent in a seated position (40.5%), the infant was consistently practicing various other positions, Supine 16.9%, Prone 14%, Upright 21.2%, Held 7.4% (^[8])