Updated: Feb 24, 2020
No really, that’s what they love to do, they just can't help it!
From around 32 weeks of pregnancy the sucking reflex begins to develop, and it lasts to around 12 months of age. This means that, within this time, when something touches the roof of the mouth the infant is triggered to suck and has no control over it.
Sucking can have a lot of different effects in the body of the baby. It is thought that sucking triggers the release of the hormone cholecystokinin in the gut which gives a feeling of fullness and sleepiness and in its turn triggers the release of oxytocin in the baby. Oxytocin is the incredible hormone which is so important throughout our lives but especially in the postnatal period and for infant development. It reduces stress, encourages social interaction, bonding and the development of a secure psychological attachment. As a result, sucking is soothing and calming and may provide a measure of pain relief.