2 min read · A tiny habit that starts surprisingly early
Imagine seeing your baby on an ultrasound with one tiny hand beside their mouth.
They may not just be resting it there.
Some babies can already suck their thumb inside the womb.
And it can begin much earlier than many parents realise.
When can babies start sucking their thumb?
By around 13 weeks, some babies may already bring a thumb towards their mouth and suck it.
At this stage, movements are still developing and you cannot feel most of what your baby is doing.
But inside, there is plenty of activity.
Owloo Did You Know?
Thumb sucking is more than a cute ultrasound moment. It helps your baby practise the sucking reflex they will need for feeding after birth.
Your baby is practising before they need the skill
Pregnancy includes many examples of your baby's body practising for life outside the womb.
Sucking is one of them.
Later in pregnancy, sucking and swallowing become increasingly coordinated — skills that will become very important once feeding begins.
Can every baby be seen sucking their thumb?
No.
Your baby's position, the timing of an ultrasound and simple chance all affect what you happen to see on the screen.
Not seeing thumb sucking on an ultrasound tells you nothing meaningful about whether your baby's development is progressing normally.
Little movements become little discoveries
Months from now, those tiny hands will be reaching, grasping and exploring outside the womb. Discover the Hello World Kit | 0–6 months.
Explore the first 6 months →Frequently asked questions
Can babies suck their thumb before birth?
Yes. Some babies can suck their thumb in the womb from early in the second trimester.
Why do babies suck their thumb in the womb?
It helps practise and develop the sucking reflex they will later use during feeding.
Should I see thumb sucking on my ultrasound?
No. Whether you happen to see it depends on timing and your baby's position, and it is not something that needs to appear on an ultrasound.
The Owloo approach
Before you have even held those little hands, they are already busy practising.
A tiny thumb. An important reflex. A glimpse of life after hello.
Written by Tina Krapez, Owloo Co-founder & COO
Sources and further reading
