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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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 occur?
The fourth growth spurt usually occurs around 19–20 weeks of life. During this stage, the baby begins to notice sequences of events and understands that actions can lead to repeated outcomes. Motor development also progresses, with more reaching, early rolling attempts, and improved ability to hold and control objects with better coordination.
What new skills appear after the fourth growth spurt?
After this stage, the baby starts to understand simple cause-and-effect relationships between actions and outcomes. They roll more actively, reach for toys, try to support themselves on their arms, and hold objects with both hands. The baby also becomes more interested in repeating actions as they begin to notice predictable patterns.
How can you help the baby during the fourth growth spurt?
Keeping a stable daily routine is important, as predictability helps the nervous system adapt. Holding the baby more often, offering calm interaction, and allowing time for movement practice are helpful. Toys with predictable effects, such as rattles and musical panels, support understanding of cause-and-effect relationships.
Why does the baby sleep worse and become more fussy?
This often happens due to nervous system overload caused by rapid development of new motor and cognitive skills. The baby may become more tired, wake up more often, and need extra comfort and attention. This is a normal developmental phase as the brain adapts to new abilities in movement, perception, and coordination.
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.
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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 2026.
- 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 2026.
- CDC’s Developmental Milestones, U.S. Centers for disease control and prevention, https://www.cdc.gov/ncbddd/actearly/milestones/index.html. Accessed 7 May 2026.
- Toddler Developmental Milestones & Safety, Cleveland Clinic, https://my.clevelandclinic.org/health/articles/22625-toddler-developmental-milestones--safety. Accessed 7 May 2026.
- 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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