Development Overview

< Month 4 Overview

The 4-month Developmental Milestone

Cute baby with beautiful blue eyes on the white backgroundAround 4 months of age babies often experience noticeable changes. This 4-month milestone marks one of the most pronounced developmental periods in a child’s life. It usually starts around of 16 weeks of age but can start later especially in babies born early.

Schedules, feeding and sleep often get off track at this time, making days and night more challenging. However, your baby will also show marked progress in brain development and awareness of the world around him.

He is discovering the world around him as he learns how to manipulate objects. He’s making connections between his actions and the reactions they produce. When he laughs, you laugh; when he drops something, it’s still there. His world is becoming more organized as he discovers the patterns and changes around him.


This new awareness takes some getting used to. Feeding, whether breast or by bottle, now has fierce competition with the dog as she walks by or locating the source of noises. As any breastfeeding Mom can attest to, nipples don’t stretch that far! Everything, whether sight, sound, smell, touch or taste is demanding his immediate attention and eating is a low priority.


Cranky BabySleep also may become challenging. Naptimes are either reduced or fought every step of the way. Night wakings occur at increased intervals. And if that’s not enough, this cognitive development stage comes around the same time that sleep cycles change; causing transitions can be very stark and easy to wake from. And he will likely need your help getting back to sleep.


This sleep-deprived, over-stimulated baby of yours may also be fussy, clingy and demanding. You may wonder if there is something wrong. There is nothing further from the truth, everything is just right. This cognitive leap usually only lasts 1-3 weeks, after which you will find yourself with a more perceptive, interactive baby.