Growing & Milestones
A percentile describes a position, not a grade
Growth charts are among the most misread documents new parents encounter. The number is a location in a population, and almost…
Growing & Milestones
What changes month by month, and how wide the normal range is.
12 articles · updated August 11, 2026
Growing & Milestones
Milestone ages are ranges, and the ranges are far wider than they look
Almost every age quoted for a first-year skill is the middle of a broad distribution. The width of that distribution is the most reassuring fact in developmental science.
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Growing & Milestones
Tummy time is a slow build measured in seconds at first
Nearly every new parent is told to do tummy time and very few are told how briefly it starts. Expecting minutes on day one is why…
Growing & Milestones
Rolling over arrives without notice, usually somewhere inconvenient
The first roll is rarely observed by anyone. It happens on a changing table, a bed or a sofa, which is why the safety habit has to…
Growing & Milestones
Babbling is already language, several months before the first word
The noises a baby makes from a few months old are not filler before speech. They are the practice that speech is built out of, and…
Growing & Milestones
Hand control develops outwards from the shoulder
Babies do not learn to use their hands all at once. Control spreads from the trunk outwards, which explains almost everything about…
Growing & Milestones
Sitting up is a balance problem the trunk solves over weeks
Sitting looks like a single achievement and is actually a gradual accumulation of trunk strength and balance reactions. That is why…
Growing & Milestones
Some babies never crawl, and it does not mean anything
Crawling is treated as a required stage and is not one. A meaningful proportion of babies get about some other way and go straight…
Growing & Milestones
Peekaboo stops being boring the week memory arrives
The moment a game about disappearance becomes funny is the moment a baby starts holding onto things that are no longer in front of…
Growing & Milestones
Stranger wariness turns up around the time a baby learns faces
A baby who smiled at everyone suddenly objects to your neighbour. It is a developmental step that arrives on its own schedule and…
Growing & Milestones
The first tooth arrives whenever it arrives, and the spread is enormous
Some babies are born with a tooth and some reach their first birthday without one, and both are ordinary. Almost everything else…
Growing & Milestones
Standing, cruising, and the long quiet gap before walking
Pulling up to stand arrives dramatically, and then a great deal appears to happen slowly. The work going on in that gap is balance…