The skull stays soft — on purpose.
About the size of a celery head — or a hare, or a chocolate log. 43.5 cm (17.1 in), 1.9 kg (4 lb 3 oz).
What's happening this week. Bones are hardening everywhere except the skull, whose plates stay separate and soft so the head can move through the birth canal. Pupils now shrink and widen with light.
Skull plates stay soft. Pupils react to light. Immune system building up.
Those soft skull plates don't fully fuse until well after the first birthday.
What your partner can do this week: Read up on the signs that labour may be starting, and ask at the next appointment when to call. Stock up on the basics: nappies, wipes, maternity pads. Keep your phone charged and on loud when you're apart.