0 to 1 Month: Your Newborn's Development Week by Week

The first four weeks of life are often described as the "fourth trimester" — a period where your baby is still completing development they would have done in the womb if human pregnancies were longer. Understanding what's happening helps you respond more confidently.

Week 1: Just arrived

Your newborn is adjusting to life outside the womb. Every sensation — light, sound, temperature, texture — is new.

What your baby can do:

• Turn head toward sounds, particularly your voice (recognised from in the womb)
• Root and suck reflexively
• Focus on objects 20–30cm away — the distance of your face while feeding
• Briefly make eye contact (fleeting and unfocused in the early days)
• Show all the primitive reflexes: Moro, grasp, stepping, rooting

What they experience:

• Sleep is fragmented — cycles of 2–4 hours, no distinction between day and night yet
• The world is a sensory shock compared to the warmth and muffled sounds of the womb
• Skin-to-skin contact regulates temperature, heart rate, breathing, and blood sugar — it's medicine

For you: The priority is establishing feeding and recovering from birth. Nothing else matters in week one. If it's not feeding, sleeping (when possible), or basic survival, it can wait.

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Week 2: Starting to settle

Physical changes:

• Regaining birth weight — should be back to birth weight by day 10–14
• Cord stump drying and beginning to separate
• Skin may still be peeling (normal)
• Yellow colouration (jaundice) fading in most babies

Behaviour:

• Slightly longer alert periods — 10–20 minutes at a time
• Beginning to focus on faces more consistently
• Feeding becoming slightly more efficient as latch improves (for breastfed babies, milk supply usually established by end of week 2)

Development:

• Hearing is fully functional from birth; begins to distinguish familiar voices more clearly
• Staring at high-contrast patterns and faces
• Reflexive smiling begins (during sleep, not social)

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Week 3: The growth spurt

The "3-week growth spurt" is one of the first recognised growth spurts and often catches parents off guard. Baby may:

• Feed much more frequently than in week 2 — sometimes every hour or two
• Be much more unsettled and difficult to put down
• Seem harder to satisfy

This typically lasts 2–4 days. For breastfeeding mothers, this is cluster feeding driving a supply increase — trust the process, feed frequently, and it passes.

Development:

• Stronger Moro (startle) reflex responses — good reminder that swaddling helps
• Slightly improved ability to lift and turn head when on tummy

Behaviour:

• Starting to be awake for longer stretches — alert periods of 30–45 minutes possible
• More responsive to voices and sounds
• May begin making small vowel sounds ("ooh", "ah") — the beginning of intentional vocalisation

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Week 4: More aware, more communicative

Physical:

• Weight gain should be well established (roughly 150–200g per week)
• Jaundice fully resolved in most babies
• Cord stump likely fallen off

Development:

• Social smiling beginning — may be the very earliest social smiles by the end of week 4, though most arrive at 6–8 weeks
• Eye contact becoming more sustained and deliberate
• Tracks moving objects more smoothly — though still jerky
• Begins to distinguish caregiver's face from strangers

Behaviour:

• Alert periods lengthening — 45–60 minutes of awake time possible before fatigue
• Evening fussiness often begins or intensifies around this time (peak fussiness at 6 weeks)
• Beginning to communicate more clearly — distinguishable crying, more varied sounds

What to focus on in the first month

Feeding: The most important thing. Fed is best. Whether breastfeeding, formula feeding, or both — successful feeding is the goal.

Respond to everything: You cannot spoil a newborn. Responding promptly and consistently to cries, fusses, and communication builds the neural pathways for secure attachment.

Skin-to-skin: As much as possible. For both parents. The evidence for its developmental and physiological benefits is overwhelming.

Talk and sing: Your voice is your baby's favourite sound and primary source of language input. Talk as you go about your day; narrate what you're doing.

Tummy time (from birth): Short, supervised sessions with you on the floor together. Even 2–3 minutes several times a day from the first days makes a difference to neck strength.

Watch for tired cues: A newborn needs to sleep after roughly 45–60 minutes of awake time. Yawning, staring into space, grimacing, turning away from stimulation — these are the cues. Getting baby to sleep before they're overtired makes settling far easier.

The 6-week check

At 6–8 weeks, your GP performs the postnatal check. For baby, this includes:

• Physical examination (heart, hips, eyes)
• Weight and growth
• Feeding assessment
• Social responsiveness — smiling, eye contact
• Your emotional wellbeing (Edinburgh Postnatal Depression Scale)

Come with questions. There's rarely a better chance to raise concerns with someone who can act on them.

Normal vs worth mentioning

Normal:

• Irregular sleep (no night/day distinction until 12–16 weeks)
• Very frequent feeding, including cluster feeding in evenings
• Reflex smiling during sleep
• Hiccups frequently
• Sneezing
• Noisy digestion

Worth mentioning:

• Not back to birth weight by 2 weeks
• Yellow skin persisting or deepening beyond 2 weeks
• Not feeding effectively or frequently enough (fewer than 8 feeds in 24 hours)
• Persistent high-pitched crying unlike usual cry
• Not waking for feeds and very difficult to rouse
• Any concern about breathing