Overview

Imagine a line that goes through the center of your child’s body. This line splits their body into a left side and a right side. This is your child’s midline. Learning to cross midline is an important developmental milestone. When your child does activities that cross midline, it means that the left and right sides of their brain are working together. Your child can cross midline with their eyes, their legs, and their hands.

When your child uses fine motor skills, crossing midline is the ability to reach across the middle of their body with their hands to do an activity. Crossing midline helps your child build a foundation for developing other fine motor skills, such as bilateral coordination, hand dominance, and dexterity. Daily living skills, like dressing and grooming, require crossing midline.

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Why crossing midline is important

Along with developing grasp patterns, the ability to cross midline is important for building other fine motor skills. Developing bilateral coordination, hand dominance, and dexterity are built on the ability to cross midline. Your child crosses midline doing most daily living skills.

• Dressing activities: Putting on their socks and shoes, putting a shirt on and taking it off, tying laces
• Grooming skills: Brushing their teeth, washing their body, ripping toilet paper for wiping
• School skills: Printing and drawing

How crossing midline develops

Your child discovers their midline as a baby. This is a voluntary movement where they learn to bring their hands together. Your baby learns to cross midline with other body parts first.

• First, your baby crosses midline with their eyes. They do this when they track (follow) you and other people or objects with their eyes.
• Next, your baby will cross midline with their legs. This helps them learn to roll.
• Finally, your baby will start to cross midline with their hands. You may notice your child crossing midline to reach for objects or help them move at 8 to 12 months of age.

As your child gets older, they learn to do more complex activities as they cross midline. By 3 to 4 years of age, your child should be comfortable crossing midline with both hands.

Issues with crossing midline

If your child is struggling to cross midline, you may notice:

• they switch hands for activities like using utensils or brushing their teeth
• they’re slower to do fine motor activities
• they shift their body to the right or left instead of reaching across their body
• they’re slower to discover their dominant hand or don’t always use the same hand as their dominant hand