Your baby at four weeks: approaching the end of the newborn stage

Newborn · Development · Reviewed 20 June 2026 · All articles

Four weeks. A whole month has passed since your baby arrived, and the exhausted, overwhelmed fog of the very first days is slowly beginning to lift. Your baby is no longer quite the same creature who came home from hospital: they are heavier, slightly less floppy, and they are starting to take in the world around them with more focus. The end of what some people call the "fourth trimester" is still a few weeks away, but you are getting close. This guide covers what is typical at four weeks: growth, feeding, sleep, physical development, and the wonderful milestones that are just ahead.

A note before we begin: the ranges below describe what is typical for most babies, not all. Development is not a race and individual variation is wide. If your baby is doing something slightly earlier or later than the figures here, that almost never signals a problem. Your health visitor or doctor is the right person to speak to if you have a specific concern.

Development at a glance

• Typical weight: birthweight plus roughly 500 to 800 g, with weekly gains of around 150 to 200 g
• Typical length: approximately 53 to 56 cm, though ranges vary considerably
• Head circumference: growing steadily, usually around 37 to 39 cm
• Head control: still requires full support at all times; brief lifting of the head during tummy time possible for some babies
• Vision: best focus at around 20 to 30 cm; beginning to track slow-moving objects
• Social: increased interest in faces; first social smile typically still two to four weeks away
• Sleep: 14 to 17 hours per 24 hours; some babies showing early hints of day-night awareness
• Feeding: breastfed babies typically feeding 8 to 12 times in 24 hours; formula-fed babies usually feeding every 3 to 4 hours

Physical development at four weeks

Your baby has been growing rapidly since birth. After an expected dip in the first few days (most newborns lose up to 10% of their birthweight before their milk supply is established), the trajectory switches firmly upward. By four weeks, most well-fed babies have gained 500 to 800 g above their birthweight. This means a baby born at 3.4 kg might now weigh somewhere around 3.9 to 4.2 kg. These are averages: some babies grow faster, some slower, and the centile chart your health visitor uses will account for where your baby started.

Length also increases steadily. Growth happens in small bursts rather than a smooth continuous line, which is why some days your baby seems to sleep more, feed more, and be harder to settle: these may coincide with a growth spurt. Growth spurts at around two to three weeks and again at four to six weeks are both common. During a spurt, frequent feeding and increased fussiness are normal and usually short-lived, lasting a day or two.

Head control is still very limited and requires your full support at all times. The muscles in your baby's neck are among the last to develop significant strength in these early weeks. However, during supervised tummy time, some four-week-old babies can briefly lift their head to one side or briefly bob it upward. This is the beginning of the head control that will develop markedly over the coming weeks. Even brief daily tummy time sessions, while your baby is awake and you are watching, help build these muscles and reduce the risk of positional head flattening.

Your baby's hands are still mostly fisted. The grasp reflex remains strong: if you place your finger in their palm, they will grip it. This is a reflex rather than an intentional action at this stage, but it is the foundation of the deliberate reaching and grasping that develops around three to four months. You may also notice your baby beginning to look at their own hands occasionally, a small but meaningful sign of developing self-awareness.

Feeding at four weeks

Feeding is likely still the dominant activity in your household, and this is completely normal. At four weeks, many families are beginning to notice that feeding patterns are starting to settle slightly compared to the chaotic intensity of the first two weeks, though there is huge variation. Some babies are still feeding very frequently indeed; others are beginning to space feeds a little more. Both can be normal.

Breastfed babies typically feed between 8 and 12 times in 24 hours. Breast milk is digested relatively quickly, which is why breastfed babies tend to feed more often than formula-fed babies. Cluster feeding, where a baby feeds almost continuously for a block of a few hours (often in the evening), is common and can feel relentless when you are in the middle of it, but it serves a purpose: it helps to regulate and boost your milk supply to meet your baby's needs. Cluster feeding does not mean you do not have enough milk.

Formula-fed babies typically feed every three to four hours, taking around 90 to 120 ml per feed at this age. Responsive, on-demand feeding is recommended for formula-fed babies too: hunger cues (rooting, hand-to-mouth movements, increased alertness and fussiness) are more reliable guides than a fixed clock. Overfeeding can occur with bottles because it is easier to encourage a baby to finish a bottle than it is to cause a breastfed baby to overfeed. Follow your baby's cues, and do not worry if some feeds are larger or smaller than others.

Signs that feeding is going well include: regular wet nappies (at least six per day after day four or five), regular dirty nappies (though frequency varies considerably for breastfed babies), steady weight gain, a baby who seems satisfied after feeds even if not always perfectly calm, and a mother who does not have ongoing nipple pain if breastfeeding (some initial sensitivity is normal but persistent pain warrants assessment by a lactation consultant or health visitor).

If you are breastfeeding and supply or latch feel like a concern, this is a good week to seek support. A lactation consultant or breastfeeding support group can help address problems before they become harder to fix. Many feeding difficulties at four weeks are very manageable with the right guidance.

Sleep at four weeks

Most four-week-old babies sleep between 14 and 17 hours out of every 24, but this sleep is spread across many short periods rather than concentrated at night. The longest single stretch of sleep is typically two to four hours, and most babies still wake at least two to three times overnight for feeds. This is biologically normal and not a sign of a problem.

Some babies at four weeks begin to show very early, very subtle signs of day-night awareness. They may be fractionally more alert and wakeful during daylight hours and sleep slightly longer at night. This is the beginning of circadian rhythm development, driven by exposure to natural light and social cues such as your voice and the general pattern of household activity. It is not yet reliable or consistent at this age, so do not expect predictable night stretches yet, but it is a glimpse of what is gradually coming.

You can gently encourage day-night awareness by keeping daytime feeds in brighter, more stimulating environments and overnight feeds quieter and dimmer. This is not about strict schedules at this age; it is just about helping your baby start to learn the difference between day and night. A consistent bedtime routine, even a very simple one (bath, feed, dark room), can also begin to be introduced at around six to eight weeks, though there is no pressure to start before you feel ready.

Sleep location matters for safety. The advice from major health organisations is consistent: a baby should sleep on their back, on a firm, flat surface, in a clear sleeping space, in the same room as a caregiver for at least the first six months. Swaddling can help some babies settle, but it should be done with the hips loose and the baby placed on their back. Never swaddle a baby who is showing signs of rolling.

Health and senses at four weeks

Your baby's senses are developing steadily. Vision is still limited: newborns can focus best at around 20 to 30 cm, roughly the distance from a breast or bottle to a caregiver's face, which is no accident. At four weeks, most babies can track a slow-moving object (a face, a gentle toy, a brightly coloured card) through a short arc. High-contrast patterns, bold shapes, and faces are the most engaging visual stimuli at this age.

Hearing is well developed from birth, and by four weeks your baby may turn toward your voice or show a response to familiar sounds. Loud unexpected noises may produce a startle reflex (the Moro reflex), which is normal and typically fades by around four to six months. Talking to your baby, narrating what you are doing, and responding to their vocalisations lays important groundwork for language development.

Touch and smell are also important. Your baby recognises you by smell and by the feel of being held. Skin-to-skin contact, holding your baby close, and responsive physical care all support attachment, help regulate your baby's temperature and heart rate, and promote your own oxytocin release. There is no such thing as spoiling a four-week-old by responding to them.

Many families have a health check around the one-month mark, though the timing, name, and format of this review varies considerably. It may be called a one-month check, a four-week review, or it may be folded into the six-week check. It typically includes a physical examination covering weight, length, head circumference, hips, eyes, heart sounds, and reflexes. It is also an opportunity to discuss feeding, sleep, your own recovery, and any concerns. If you have not had a check offered at four weeks, the six-week check is standard in most places and will cover the same ground.

If at any point you notice symptoms that concern you, including high or low temperature, persistent poor feeding, unusual drowsiness, a rash that does not fade when pressed, difficulty breathing, or a general sense that something is not right, seek medical attention promptly. You know your baby best, and instinct is a valid reason to call.

What comes next: the six-week milestone

Six weeks is one of the most meaningful early milestones, and you are two weeks away from it. Several things tend to shift around that mark, though again, individual babies have their own timelines.

The first genuine social smile is the most anticipated. Between six and eight weeks, most babies produce their first real smile in response to a face or voice, one that lights up their whole face and represents actual social engagement rather than a reflex grimace. If your baby has not smiled by eight weeks, mention it at the next health check, but the range is wide and some babies take a little longer. You will know the real smile when it comes, and it tends to feel transformative after weeks of intense, one-sided caregiving.

Colic and crying often peak around six weeks. If your baby has been particularly unsettled or has had periods of intense, inconsolable crying in the late afternoon or evening, this is often described as colic. The exact cause is not fully understood. The good news is that for most babies it improves markedly by three months. If crying feels relentless or overwhelming, speaking to your health visitor is worthwhile; there are some strategies that help some babies, and there is support available for caregivers too.

Around six weeks, many parents also notice feeding beginning to feel slightly more efficient and predictable. Breastfed babies tend to feed more quickly as the latch becomes well established and the baby becomes more experienced. Feeds that took 45 minutes at two weeks might take 15 minutes by six weeks. This is a good sign, not a sign that the baby is not interested or not getting enough.

Your own six-week postnatal check (in places where this is offered) covers your physical and emotional recovery, including any symptoms of postnatal depression or anxiety. This check matters. If you are struggling with your mood, feeling persistently overwhelmed, or having intrusive thoughts, being honest at this appointment or with someone you trust can open doors to effective support.

Frequently asked questions

How much weight should my baby have gained by four weeks?

Most well-fed babies have regained their birthweight by around ten to fourteen days and then gained an additional 500 to 800 grams above birthweight by four weeks. Average weekly gain in this period is roughly 150 to 200 grams per week. Babies vary considerably, so if your baby is growing steadily along their own curve and feeding well, that is more meaningful than any single number. Your health visitor or midwife will plot weight on a centile chart to assess whether growth is on track.

When will my baby smile at me for the first time?

The first genuine social smile, meaning one that is a real response to your face and voice rather than a reflex, typically appears between six and eight weeks of age. At four weeks many babies are beginning to watch faces more attentively and may hold eye contact for a few seconds at a time, which is the groundwork for that first smile. The six-week mark is when most families notice the real thing, though some babies take a little longer and that is completely normal.

Is it normal for a four-week-old to sleep all day?

Yes. At four weeks most babies still sleep between 14 and 17 hours in every 24, spread across many short stretches. Some babies at this age are beginning to show very slight signs of day and night awareness, such as being slightly more alert during daylight hours, but this is not yet consistent or reliable. The shift toward longer night sleep and more wakeful daytime periods develops gradually over the coming weeks and months. If your baby is feeding well, gaining weight, and having wet and dirty nappies, their sleep pattern is likely normal for this age.

What happens at the one-month or six-week check?

In many places a health review is offered around one month or six weeks of age. This typically includes a physical check of the baby covering weight, length, head circumference, hips, eyes, heart, and reflexes. The person conducting the check will also ask about feeding, sleep, and how the family is coping. It is a good opportunity to raise any concerns you have, however small they seem. The exact timing and who carries out the check varies by location: it may be a GP, a health visitor, a paediatrician, or another maternal and child health professional.