Baby Growth Spurts: When Do They Happen, How Long Do They Last, and What Are the Signs?

Is your baby suddenly demanding milk every hour, seeming constantly hungry and fussier than usual? They may be going through a growth spurt. These periods most commonly occur around 7 to 10 days, between 3 and 6 weeks, and between 3 and 4 months. They usually last a few days, after which your baby's appetite returns to its usual pattern.

Here's when growth spurts typically happen, how to recognise the signs, what really helps, and how they differ from the “developmental leaps” described in many parenting books and apps.

What Is a Baby Growth Spurt?

A growth spurt is a short period during which a baby grows more quickly than usual. Their need for milk increases, so they may want to feed more frequently and sometimes for longer.

A baby's growth doesn't follow a perfectly steady pattern. Some studies suggest that growth can happen in bursts, with periods of faster growth alternating with quieter phases. However, every child develops at their own pace.

During these periods, an increased appetite is normal: your baby needs more milk to meet their growing needs. If you're breastfeeding, more frequent feeds also help stimulate milk production.

A growth spurt is not an illness and doesn't require any treatment.

Growth Spurts vs. Developmental Leaps: What's the Difference?

These two concepts are often confused, but they refer to different aspects of a baby's development:

• A growth spurt involves physical growth: your baby's body grows, and they may become hungrier for a few days.
• A developmental leap involves new skills: your baby learns to smile, grasp objects, roll over, crawl, or walk.

The idea of developmental leaps occurring at specific weeks was popularised by the book The Wonder Weeks and its accompanying app.

An independent study published in 1998 did not confirm the existence of these ten developmental periods at fixed ages, although the study involved only a small number of babies.

Developmental milestones are real, but they don't necessarily follow exactly the same timetable for every child.

According to the World Health Organization (WHO), for example, healthy children typically begin walking independently between approximately 8 and 18 months.

At What Age Do Baby Growth Spurts Happen?

Growth spurts are commonly reported at three particular stages during the first few months of life.

However, these ages are only general guidelines. Your baby may experience a growth spurt slightly earlier or later, or at entirely different times.

Around 7 to 10 Days

The first growth spurt often occurs during the second week of life.

Just as your baby is beginning to settle into a feeding routine, they may suddenly start demanding milk much more frequently.

Between 3 and 6 Weeks

This is one of the periods parents talk about most, particularly the well-known “3-week growth spurt” and “6-week growth spurt”.

Breastfeeds or bottles may become much more frequent, sometimes as often as once an hour.

Between 3 and 4 Months

Another increase in appetite is common between 3 and 4 months.

This also happens to be a period when babies' sleep patterns are changing. Their sleep cycles gradually become more structured, a development often associated with the 4-month sleep regression.

What About Growth Spurts at 6, 9, or 14 Months?

After 4 months, growth spurts become harder to identify, and their timing is less predictable.

Changes observed around 6, 9, or 14 months may also be linked to other developmental milestones, such as learning to sit, crawl, or walk.

Your baby may also be getting their first teeth, which usually begin appearing around 6 months, or experiencing separation anxiety, which often starts around 8 months.

If your baby suddenly seems hungrier at these ages, pay attention to their hunger cues and respond to their needs without necessarily trying to link every change to a growth spurt.

Baby Developmental Milestones from Birth to 18 Months

Developmental milestones are useful reference points, not strict deadlines that every child must meet.

For ages 2, 4, and 6 months, the milestones listed below are skills achieved by at least 75% of children at that age, not necessarily all children.

For the other milestones, the age ranges indicate when almost all healthy children develop the corresponding skill.

For more information, read our article: When Do Babies Start Rolling Onto Their Side or Tummy?

How Long Does a Baby Growth Spurt Last?

A growth spurt usually lasts just a few days. Afterwards, your baby's appetite generally returns to its usual pattern.

If your baby continues to demand significantly more milk than usual for over a week, or if other symptoms appear, such as fever, inconsolable crying, or fewer wet nappies, speak to your paediatrician.

There may be another reason for the change in your baby's behaviour.

How Can You Recognise a Baby Growth Spurt?

The most characteristic sign of a growth spurt is a sudden increase in appetite.

You might notice that:

• Your baby wants to feed more frequently, sometimes as often as every hour.
• Breastfeeds last longer, or your baby finishes their bottle and still seems hungry.
• Your baby seems fussier between feeds and seeks more physical contact and reassurance.

However, crying or increased fussiness without a noticeable change in appetite may have other causes.

If your baby is particularly unsettled at night, our article Why Does My Baby Cry at Night, and What Can I Do? can help you explore other possible explanations.

Growth Spurts and Sleep: Do Babies Sleep More or Less?

A growth spurt doesn't necessarily mean your baby will sleep less.

Some babies seem to need more sleep during these periods, while others wake more frequently because they're hungry.

A study published in 2011, involving 23 infants, observed an association between certain periods of longer sleep and increases in body length during the following days.

These findings are interesting, but they don't allow us to predict how every baby will sleep during a growth spurt.

The most important thing is to observe your baby's individual needs and respect their natural rhythm.

To learn more about this connection, take a look at our article Sleep and Growth: An Invisible but Essential Connection.

If your baby's nights remain unsettled for several weeks, there may be another explanation. Our articles on baby sleep regressions and frequent night waking can help you understand what might be happening.

What Can You Do During a Baby Growth Spurt?

Growth spurts can be tiring, particularly when your baby suddenly wants to feed much more frequently than usual.

Fortunately, you don't need to change your entire routine. A few simple steps can help you and your baby through these intense few days.

• Feed your baby on demand: If you're breastfeeding, offer the breast whenever your baby shows signs of hunger. More frequent feeding helps stimulate your milk supply. If you're bottle-feeding, follow your baby's hunger cues and speak to your paediatrician if you think they need larger quantities. Never change the recommended ratio of formula powder to water.
• Offer plenty of closeness and comfort: Cuddles, babywearing, and quiet moments in your arms can help reassure your baby during these more demanding days.
• Respect your baby's naps: If your baby seems to need more sleep, let them rest. During the first few weeks of life, however, follow your midwife's or paediatrician's advice regarding feeding intervals. You can also read our guide to naps for babies and young children.
• Keep familiar bedtime routines: A simple, consistent evening ritual helps your baby recognise when it's time to sleep. Discover our ideas for bedtime routines for babies.
• Look after yourself too: Make sure you drink enough water, eat regularly, and take turns during the night with your partner if possible. Remember, these particularly demanding days usually pass.

When Should You Contact Your Paediatrician?

An increased appetite for a few days is usually normal. However, it's important not to assume that every change in your baby's feeding or behaviour is caused by a growth spurt.

Contact your paediatrician if:

• Your baby is under 3 months old and has a temperature of 38°C or higher. Seek medical advice immediately.
• Your baby has a fever or seems unwell.
• They are drinking less than usual or refusing feeds.
• They have fewer wet nappies than normal.
• They are not gaining weight or are losing weight.
• They cry inconsolably or appear to be in pain.
• Their appetite remains significantly increased for more than a week.
• You feel exhausted, overwhelmed, or unable to cope.

Comfortable Sleep with Zizzz

During periods when your baby wakes more frequently to feed, a Zizzz baby sleeping bag provides warmth suited to the room temperature without the need for a loose blanket in the cot.

A properly fitting sleeping bag also allows your baby to move freely, keeping their arms unrestricted and leaving plenty of room for their legs to kick and wriggle.

Zizzz sleeping bags are made with Swisswool and organic cotton. To choose the right level of warmth, take a look at our TOG rating guide.

For older children, our cuddly toys, made with an outer layer of 100% organic cotton and a filling of 100% Swisswool, can become a familiar and comforting part of their bedtime routine.

Important: For babies under 12 months, the cot should remain free from cuddly toys, soft toys, and other soft objects.

Frequently Asked Questions About Baby Growth Spurts

How Long Does a Baby Growth Spurt Last?

A baby growth spurt usually lasts a few days.

If your baby's appetite remains significantly increased for more than a week, or if other symptoms appear, speak to your paediatrician.

At What Age Do Babies Have Growth Spurts?

Growth spurts are most commonly reported around 7 to 10 days, between 3 and 6 weeks, and between 3 and 4 months.

However, they can also occur at other times during the first few months, and every baby develops at their own pace.

Do Babies Sleep More During a Growth Spurt?

Not necessarily.

Some babies seem to need more sleep during these periods, while others wake more frequently to feed.

A small study found an association between longer periods of sleep and increases in growth during the following days. However, these findings cannot predict the sleep patterns of every baby.

Pay attention to your baby's usual needs and respect their individual rhythm.

Can Babies Have Growth Spurts at 6, 9, or 14 Months?

Yes, it's possible. However, after 4 months, growth spurts become harder to identify and less predictable.

Changes observed around 6, 9, or 14 months may also be related to new developmental milestones, teething, or separation anxiety.

Are Growth Spurts and Developmental Leaps the Same Thing?

No.

A growth spurt involves physical growth: your baby grows and may become hungrier for a few days.

A developmental leap refers to the acquisition of new skills.

The timetable of the so-called “Wonder Weeks” comes from a book, and an independent study published in 1998 did not confirm that these periods occur at fixed ages.

Sources

• INSPQ, From Tiny Tot to Toddler – Growth spurts in newborns: common ages, duration, and increased appetite during growth spurts.
• Lampl M. et al. – Saltation and Stasis: A Model of Human Growth, Science, 1992: research on growth occurring in bursts during infancy.
• Lampl M., Johnson M. L. – Infant Growth in Length Follows Prolonged Sleep and Increased Naps, Sleep, 2011: study examining the relationship between sleep and growth in 23 infants.
• World Health Organization (WHO) – WHO Motor Development Study: Windows of Achievement, Acta Paediatrica, 2006: age ranges for sitting without support, crawling, and walking independently.
• CDC – Developmental Milestones: developmental milestones at 2, 4, and 6 months, achieved by at least 75% of children at the corresponding ages.
• MSD Manuals – Separation Anxiety and Stranger Anxiety: typical age of onset and development of separation anxiety.
• Sleep Foundation – Baby Sleep Cycles: how babies' sleep cycles develop around 3 to 4 months.
• NHS – Baby Teething Symptoms: when babies' first teeth typically appear.
• de Weerth C., van Geert P. – Emotional Instability as an Indicator of Strictly Timed Infantile Developmental Transitions, British Journal of Developmental Psychology, 1998: independent research examining the proposed timetable of the “Wonder Weeks”.
• NICHD – Safe to Sleep (French-language brochure): safe sleep recommendations, including keeping soft toys and other soft objects out of a baby's cot.

This article is for informational purposes only and is not a substitute for professional medical advice.