Spots and stripes of light play over me. I jump and box and face the camera which is not what you want, you, lying there jubilant at my dirt grey swirl of flesh, fists and hollows. My little fist, you say, as I knuckle under and point out. You can't see my colours and so what if it's true that I can't judge how small you are, on that high bed, the sonar sensor sponging over you, my house, hair half as long as your body. You rod-like hair-bound nub of mother – what will we say when we are in different skins?

A nuchal scan measures the nape of a twelve week old unborn baby's neck.