Your baby's suck is actually a grasp reflex
The area of your baby’s brain that controls the movement and sensation of their mouth and tongue was one of the first to develop before they were born, and they will have been practising moving their mouth and sucking for some time before they made their debut in your life!
The sucking reflex for feeding
The sucking reflex ensures that your baby can feed after birth, so when something touches the roof of their mouth they will suck. This action is essentially a grasp reflex, as your baby uses their mouth to hold the nipple or teat to feed.[1]
Your baby's sucking motion will change over the coming months
The movements that your baby makes when sucking will develop during the first month. Initially, they will use up and down movements of the jaw, then side to side movements, before starting to use back and forth movements of the jaw when they suck.[4]
In the first few months, your baby’s muscles will develop and they will be able to suck more quickly and efficiently and adapt the way that they suck according to the flow of milk, taste and temperature.[2]
As your baby develops, the sucking reflex will gradually be integrated as sucking becomes an action that they control rather than one that is dependent on a reflex.
How it develops other muscles and movements
The movements involved in sucking and swallowing help to develop the muscles of the mouth and tongue, as well as supporting the development of the voice box, throat and the ability to breathe through their noise, all of which contribute to the development of vocalisation and speech.[1] Sucking when feeding uses various parts of the brain as your baby coordinates their movements and breathing in order to suck and swallow.[2]
Their mouth will become their tool for exploration!
The area around the mouth is an area that remains sensitive to touch throughout our lives and is used by babies to explore the world and to find out about their bodies and objects.
As your baby’s physical skills develop, they will bring their hands and objects that they are holding to their mouth and use their mouth and tongue to feel and explore them. Over the coming months, your baby will begin to suck not only for nutrition and comfort, but also for more exploring, and this helps them to learn about objects while developing their mouth and tongue muscles.[3]
References:
[1] Goddard-Blythe, S. (2004). The Well Balanced Child: Movement and Early Learning. Stroud: Hawthorn Press.
[2] da Costa, S., van den Engel–hoek, L. & Bos, A. Sucking and swallowing in infants and diagnostic tools. J Perinatol 28, 247–257 (2008). https://doi.org/10.1038/sj.jp.7211924. Accessed 11th October 2021
[3] Owens, R.E. (2001). Language development: An introduction (5th Ed.). New York: Merrill.
[4] Gotzke, C. & Sample Gosse, H. (2007). Research Review: Vocalizing 0 - 3 Months. In L.M. Phillips (Ed.), Handbook of language and literacy development: A Roadmap from 0 - 60 Months. [online], pp. 1 - 8. London, ON: Canadian Language and Literacy Research Network. Available at: Handbook of language and literacy development