The week your baby changes and you can't say how

It happens two or three times a year, and it is always slightly unsettling.

You look at your child across a room and something has moved. Not grown — moved. The proportions of the face are different. The way they hold their shoulders is different. They look, for a moment, like a slightly older person you haven't met yet.

And if someone asked you what changed, you could not tell them.

Development doesn't happen in a straight line

The milestone lists give a misleading impression, because a list has to be made of nameable items: sits, crawls, walks, points, waves, says a word.

Those are real. But they are the visible edges of something much less tidy, and a great deal of what happens between them has no name at all. A week where sleep falls apart for no reason and then reassembles differently. A week where they suddenly find something funny that wasn't funny before. A week where they go quiet and watchful and then come out the other side doing something new.

"Nothing happened that week. He just came out of it as a different child."

Nobody asks about those weeks at a check-up, because there is no box for them. So they leave no trace.

Why you can't see it while it's happening

Because you're too close, and because it's gradual enough to hide inside a normal week.

Parents almost never notice their own child's changes in real time. They notice them in photographs, or when someone who hasn't visited for two months walks in and says something. The gap between what you see daily and what an outsider sees is, roughly, the size of the change.

Which is why the useful record isn't a description. You can't describe what you can't name. The useful record is something comparable.

The comparable version

Two things, both small.

• A photo in the same place, roughly monthly — same chair, same doorway, same corner of the sofa. Not a nice photo. A repeatable one.
• One line about how the week felt, even when nothing measurable happened: unsettled, sleeping badly, watching everything. Suddenly affectionate. Quiet all week, then talking more.

Alone, each is nothing. Six of them in a row show you a shape — and the shape is usually the thing you were trying to describe and couldn't.

What it's actually for

Partly it's just interesting. Read back a year of those lines and the growth spurts, the leaps and the flat patches are all visible, in a way they never were while you were living through them.

But there's a practical side too. "He's been different since about mid-October" is a much better sentence to be able to say — to a partner, to a grandparent, to a doctor — than "I don't know, something's changed."

The milestones will get recorded whatever you do; everyone remembers the first steps. It's the weeks in between, the ones that don't produce anything nameable, that need someone to write one line and move on.