Thanks everyone for the comments. This picture was taken for her passport, and the rules for mugshots set by Her Britannic Majesty were my original motivation for the layout and style of the shot.. It turned out so well that I'd like to refine the look for something even better, although I'm still aiming for a straightforward portrait (sorry Tony).(posted 8432 days ago)The major point that the background lighting needs to be improved has been taken on board. I don't mind a touch of unevenness or a hint of shadow, but the way the uplighting dominates here is certainly wrong - she's not starring in a horror movie.
Her right hand will also have to be tamed. From this roll, both the shots with this best-of-set facial expression had her twiddling her fingers like this. As a proud dad I couldn't care less, but I agree that photographically that finger looks odd and leads the eye out of the frame.
Other things are more a question of taste. I can't agree with the suggestion to use B+W. I love B+W portraits, but the whole point here is the blobs on pink on a white ground, and in any case it would be a crime to desaturate those sapphire blue eyes. I also like to give my subjects space in the frame, so tight cropping is also out for me.
I appreciate the responses. If the sun ever comes out again during a period when she's not asleep or colic-ridden I'll try another portrait encorporating your suggestions.