Baby development stages
Let us divide the baby’s first year of life into several periods of 3-4 months each and explore how their skills, reflexes, and desires evolve through time.0 - 3 Months
A newborn baby may seem both like a doll and, in some ways, like an alien: their head is much larger than their body; their hands and legs move randomly; their dazed eyes are wide open, ready to take in the world. Many babies, just after birth, are able to crawl from their mother’s belly to her chest, seeking the nipple by its scent, latching on, and beginning to drink colostrum (the special milk that comes before mature milk). The sucking reflex is incredibly strong and present even in babies born by caesarean section.
What can the baby look forward to?
Physiology:
Normally, by 5 weeks of age:
- the baby can briefly hold their head up while on their stomach, especially when you run a hand along the spine;
- the flexor muscles are stronger than the extensor muscles, so the newborn’s natural pose is still the curled embryonic position.
- turn their head while lying on their back and focus on an interesting object for a few seconds;
- move arms and legs more freely, developing their extensor muscles. The fetal position fades away.
- hold their head up while on their stomach, and their arm and leg movements become less chaotic;
- reach for objects or sources of sound and light;
- if held under their arms, attempt to steady themselves on their legs.
Up to 5 weeks old, infants:
- respond to sounds and can distinguish familiar voices;
- focus on shiny or bright objects.
- smile in response to adults’ smiles, make cooing sounds, and show pleasure when held by close caregivers;
- have a positive reaction and seem to anticipate feeding;
- track objects with their eyes and start noticing their own hands.
- can become bored if not stimulated—this sign of mental growth is shown by crying when not actively engaged or when stimulation is monotonous;
- explore their bodies and faces with their hands;
- show special interest in human speech;
- recognize their mother and other close caregivers.
- Respond to your baby’s cries, hold them, and talk to them. At this age, a baby’s crying signals hunger, need for comfort, or desire for skin-to-skin contact. All these needs are crucial for healthy development in the first three months.
- Emotionally and verbally encourage their early achievements. All healthy babies will eventually hold up their heads, focus on toys, or brace their legs, but your praise and approval foster positive feelings towards their progress, inspiring further development.
- Change your baby’s position often. If your baby is frequently on their back, ensure some tummy time and carry them upright, narrating what’s happening around you.
- Help them gain control over arm and leg movements—attach small bells to their legs for short periods.
At this stage, a baby begins to perceive the world differently. They notice changes, both around them and within themselves. The world is no longer an indistinct mix of internal and external sensations.
Around 12 weeks old, a period of rapid development may occur, which can make babies fussier or, conversely, more withdrawn. They may develop a stronger attachment to their mother and experience sleep or waking disturbances. This “growth spurt” typically lasts 7-10 days and then fades.
Physiology:
After 12 weeks babies can:
- sit with support;
- roll from tummy to back;
- actively reach for and try to grab objects.
- lifting head and shoulders while lying down;
- passing objects from one hand to the other;
- participating actively in feeding: holding or guiding the bottle, massaging mother’s breast.
- sit up alone for a short time without support;
- pick up small items from a flat surface using a “claw” grip (thumb opposed to fingers);
- try crawling by kicking their legs.
At 12 weeks babies show:
- many positive reactions (laughter, smiles) to parents’ faces and their own reflection in a mirror;
- interest in repetitive games with familiar adults;
- increasing variety in sounds, imitating adult intonation.
- initiate play, make sounds, and manipulate toys to attract adult attention;
- begin to experience and show fear and anger. They may resist when toys are taken;
- show interest in moving objects: throw and watch the same object repeatedly; track moving things;
- tell the difference between familiar and unfamiliar people;
- start pronouncing some consonants.
- comparing objects in different hands, exploring differences in size, shape, texture, and sounds.
- responding to their name with smiles or sounds;
- watching other children closely;
- reaching for dropped toys, showing longer-lasting interest.
- Don’t restrict your child’s movement or scold them for exploring: curiosity drives development. Just create a safe space—secure gates on stairs, cover open banisters, childproof outlets, etc.
- Play often! Hide your face (“Where’s mommy?”), tickle, give gentle massages, bicycle their legs, and play brief tossing games.
- Talk with lots of expression and mimic your child’s facial gestures. Strong imitation skills develop at this stage.
6 - 9 Months
By this stage, babies discover distances and space. Many can crawl or cruise along furniture. Their mobility increases—and so does their realization of how big the world is. This knowledge can make them wary or anxious when separated from a parent, even in another room.
Physiology:
By 24 weeks babies can:
- grasp objects with a "claw" grip;
- hold tightly and use a butterfly teether, eat a breadstick or biscuit independently.
- sit well unaided;
- crawl quickly and skillfully;
- crawl up stairs or onto sofas on all fours.
By 24 weeks a child develops:
- their first words: “mama”, “dada”, “give (me)”, etc.;
- fear or suspicion of strangers;
- understanding of “no” and “not allowed”;
- protest or anger when freedom is restricted (e.g., seatbelts, playpens).
- enjoy spatial games—building “towers” with blocks, for example;
- get bored with repetitive games;
- separate toys into favorites and others, often choosing a “forever friend” toy at this age;
- develop awareness of ownership, may dislike others touching their things.
- Respect their negative feelings. Don’t dismiss or immediately try to cheer your baby up when they are upset. Let them feel the emotion, describe it for them (“That hurt,” “You’re sad your toy is gone.”), then gently redirect their attention.
- Let your baby choose which adults to interact with. There’s no need to insist on polite greetings or cuddles to all adults just yet. Respect their need for personal space.
- Allow them to discover what isn’t allowed or is dangerous under supervision, like touching something warm or safe exploration with adult guidance.
By this age, children begin to understand sequences and regularities in the world. For example, they learn that a small object can fit on a bigger one, a round one will roll, or a small box can fit inside a larger one. More complex ideas become clear, and your child may become demanding with themselves and their abilities.
Physiology:
By 36 weeks children can:
- stand alone or with minimal support;
- move along furniture or while holding an adult’s hand;
- pick up small objects and place them in containers;
- use a spoon or crayon.
- walk unaided;
- sit down and stand up independently;
- walk up and down stairs holding onto a banister;
- help with dressing and undressing themselves.
By 36 weeks babies:
- experience and express a wide range of emotions, understanding them in others, especially close people;
- feel jealous of parental attention, especially toward other children;
- move toys from place to place, often without looking;
- understand the function of objects: rattling a rattle, building with blocks, throwing a ball;
- connect words and actions: “stamp”, “clap”, etc.;
- follow simple instructions like “give me” or “put it down”.
- may show stubbornness and start protesting familiar routines;
- enjoy sorting objects by color and size;
- can say several words together, making their first sentences. Girls may do these slightly earlier than boys;
- remember and recognize events from yesterday or even last week.
- Encourage with words, eye contact, gestures, and touch—rather than food or toys.
- Support and initiate games with stacking rings, blocks, and sorting toys.
- Allow your child to eat and drink independently, using safe, plastic utensils.
- Let your child help with dressing—putting on slippers or a hat by themselves, and don’t correct them if it’s a little crooked.