What Happens During the Fourth Growth Crisis
 Category | Growth crises |
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Medically reviewed by pediatrician and perinatal psychologist Polina Kizino
During the fourth growth crisis, your baby starts to understand that actions can repeat and lead to outcomes. They reach for toys, roll over, hold objects with both hands — and tire quickly. Sleep may get worse, and your baby may seem fussier. Support them with familiar routines, gentle physical contact, and time to practice new skills.
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What’s Inside
Quick takeaways
- The fourth growth crisis usually occurs around weeks 19–20.
- The baby learns to recognize familiar actions: shake the toy — it makes a sound, mom leaves — she might come back.
- Anticipation of events develops — the baby responds to pauses and predictable situations.
- Active movement appears: rolling over, reaching, holding toys with both hands.
- The baby may become more anxious, sleep worse, and demand more attention — this is normal and temporary.
Understanding sequences
This is the first crisis where the baby begins to anticipate what’s next. They notice that events follow each other:
- After babbling — mom pays attention or picks them up
- Pulling a ribbon — the toy moves
- Lights off — it’s time to sleep
This is a key stage of cognitive development, laying the groundwork for cause-and-effect thinking
Motor skills take a leap
Alongside mental development, the body progresses too:
- Rolling from back to tummy
- Trying to push up with arms
- Grasping objects with both hands
- Reaching toward toys
The baby becomes more focused, tries to achieve goals. This requires coordination, effort — and often leads to fatigue and overstimulation.
Why your baby may seem fussy
Parents often feel like their baby is “off” during this stage:
- Sleeping worse
- Refusing usual routines
- Asking to be held more often
- Crying for “no reason”
This is a normal nervous system response to development. The baby is adjusting to new ways of sensing and moving, which takes time.
New skills — physical or emotional — can also overstimulate, causing fatigue and sleep disruptions.
How to support your baby
- Keep a familiar daily rhythm — predictable routines reduce stress
- Hold your baby more — physical contact eases anxiety
- Give time for new movements — don’t rush or over-correct
- Offer toys with predictable outcomes: rattles, hanging toys, musical panels with buttons
- Speak in simple phrases with pauses — this supports speech understanding
Frequently Asked Questions About the Fourth Growth Spurt
When does the fourth growth spurt happen?
The fourth growth spurt usually occurs around 19–20 weeks of age. During this period, babies begin to recognize patterns, anticipate events, and become more active in their movements.
What new skills develop during the fourth growth spurt?
Babies start noticing that actions lead to predictable outcomes. They may roll over, reach for toys, hold objects with both hands, and show greater interest in how things work.
How can I support my baby during the fourth growth spurt?
Keep daily routines predictable, offer plenty of physical contact, and allow time to practice new movements. Toys with clear cause-and-effect actions, such as rattles or button-activated toys, can also be engaging.
Why is my baby fussier and sleeping worse?
The nervous system is adapting to new ways of understanding and interacting with the world. As babies process new skills and experiences, they may become more tired, need extra comfort, and have temporary sleep disruptions.
With care
Our articles are based on evidence-based medicine and reviewed by pediatricians. However, they do not replace a consultation with your doctor. Every child is unique — if you have any concerns, please consult a medical professional.
Sources
- Plooij FX, van de Rijt-Plooij H. The Wonder Weeks: How to Stimulate Your Baby's Mental Development and Help Him Turn His 10 Predictable, Great, Fussy Phases into Magical Leaps Forward. Kiddy World Publishing; 2017. ISBN: 978-9491882166
- Child growth standards, WHO, https://www.who.int/tools/child-growth-standards/standards. Accessed 7 May 2025.
- 12 month developmental milestones, UK National Health Service, https://www.cambspborochildrenshealth.nhs.uk/child-development-and-growing-up/milestones/12-months/.
- National Research Council (US) and Institute of Medicine (US) Committee on Integrating the Science of Early Childhood Development. From Neurons to Neighborhoods: The Science of Early Childhood Development. Shonkoff JP, Phillips DA, editors. Washington (DC): National Academies Press (US); 2000. PMID: 25077268. https://pubmed.ncbi.nlm.nih.gov/25077268/.
- and de Onis, M. (2006), WHO Motor Development Study: Windows of achievement for six gross motor development milestones. Acta Pædiatrica, 95: 86-95. https://doi.org/10.1111/j.1651-2227.2006.tb02379.x. Accessed 7 May 2025.
- CDC’s Developmental Milestones, U.S. Centers for disease control and prevention, https://www.cdc.gov/ncbddd/actearly/milestones/index.html. Accessed 7 May 2025.
- Toddler Developmental Milestones & Safety, Cleveland Clinic, https://my.clevelandclinic.org/health/articles/22625-toddler-developmental-milestones--safety. Accessed 7 May 2025.
- Misirliyan SS, Boehning AP, Shah M. Development Milestones. 2023 Mar 16. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–. PMID: 32491450. https://pubmed.ncbi.nlm.nih.gov/32491450/
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