From the Research
Yes, it is completely normal for newborns to suck on their fingers or hands as a self-soothing mechanism, even when they are well-fed. This behavior is a natural reflex that begins to develop even before birth, with ultrasounds often showing fetuses sucking their thumbs in the womb. Sucking is one of a newborn's primary reflexes and serves multiple purposes beyond just feeding. It helps babies calm themselves, regulate their emotions, and cope with new stimuli in their environment. This non-nutritive sucking (sucking not associated with feeding) is a healthy developmental behavior that helps infants learn to comfort themselves. Most babies will naturally engage in finger or hand sucking when they're tired, overstimulated, or simply exploring their bodies.
According to a study published in 2015 1, research using anatomical and neurophysiological data explains why an infant forms the habit of thumb sucking from a neurological standpoint, abandoning the psychological explanations proposed until now. The study analyzed 40 thumb-sucking subjects with ages ranging from 5 to 25 years and a control group of 20 non-thumb-sucking subjects, evaluating postural and neurological effects of thumb sucking. The results obtained confirm that a thumb-sucking subject puts the thumb in the mouth to stimulate the nasal-palatal receptors of trigeminus and obtain muscular balance and a release of physical and psychological tension.
Parents should not be concerned about this behavior or try to stop it in newborns and young infants. As children grow older, most will naturally outgrow this habit, typically between ages 2-4, though some continue thumb-sucking longer. Only if the habit persists well into the preschool years might it become a concern for dental development, as suggested by a study published in 1989 2. However, a study published in 2005 3 reported a case of onycholysis in a 6-month-old male infant secondary to chronic finger sucking, which resolved after cessation of finger sucking habits when the child was a toddler.
Some key points to consider:
- Newborns spend about half an hour per hour sucking a pacifier or finger(s) starting on the very first day of life, as reported in a study published in 1982 4.
- Non-nutritive sucking does not result in the development of sucking behavior, as suggested by a study published in 2001 5.
- An oral feeding practice is necessary for the development of sucking behavior, as reported in a study published in 2001 5.
Overall, parents should not be concerned about finger sucking in newborns and young infants, as it is a normal and healthy developmental behavior.