Child development at age 3-6 months

The phase between 3-6 months in a baby’s life is characterised by rapid learning processes on the cognitive, social-emotional and communication levels. At the same time, the body becomes stronger and enables the baby to be more active. Another special milestone is that the baby's first teeth may begin to show.

Baby playing with toys
Baby's body development at age 3-6 months

Baby’s body

At the age of 3-6 months, coordination improves and babies are capable of basic purposeful actions such as transferring objects from one hand to the other. Also, muscle strength  grows, which enables the baby to hold its head on its own. 
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Baby’s mind

Babies’ minds grow continuously at the age of 3-6 months, with each baby gaining new impressions and trying new things every day. They learn repeated behaviours and explore sound and noises. 
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Baby playing with rattle
Baby's mental development at age 3-6 months
Baby with her first teeth
Nutrition at age 3-6 months


During the 3rd-6th months of a baby’s life, the development of bones and teeth are of particular note. Calcium, phosphorus, and vitamin D are important nutrients that support bone and teeth mineralisation as well as other biological processes. The main source of these nutrients for babies is still breast milk or infant formula. At this age, babies mostly reach the daily calcium dosage (about 200-300mg per day) and phosphorus dosage (about 100mg per day) through breast milk, however vitamin D is often supplemented, particularly in northern countries. The energy requirement of approximately 500kcal per day can normally be satisfied via breast milk or infant formula alone.
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  • Baby's body

    The main milestones for babies aged 3-6 months include:

    • teething, which causes gum swelling and irritation;
    • using the tongue to move food inside the mouth and closing their lips when swallowing;
    • starting to suck hands and thumbs;
    • inspecting objects using their hands, eyes and mouth;
    • grasping toys or objects without using the thumbs;
    • transferring objects from one hand to another
    • being capable of supporting a bottle for self-feeding;
    • starting to roll over, from their back to their stomach or sides; and
    • bearing increasing weight and being able to hold their head when held in an upright position.

    (Bartolotta and Shulman, 2010; UNICEF, n.d.; University of Pittsburgh, 2015)

  • Baby's mind

    Babies receive countless impressions throughout the day. Their mind is growing fast. At 3-6 months, infants: 

    • are able to anticipate being fed, even opening their mouth when seeing food;
    • repeat arm or leg movement to cause actions occurring several times in a row; 
    • intentionally drop objects just to see them fall;
    • imitate sounds not related to speech such as tongue clucking and lip smacking; 
    • reproduce sounds and noises when they are talked to;
    • are able to laugh aloud;
    • are able to vocalise likes and dislikes
    • are able to recognise their own image in a mirror or picture and smile and pat it in response 
    • initiate social interactions; and
    • react in a different way to familiar caregivers and to strangers.

    (Bartolotta and Shulman, 2010; UNICEF, n.d.; University of Pittsburgh, 2015)


More about babies' natural growth path