Nightshirt for post delivery - 1 size larger than usual or more?

[Easter2020]

Hi ladies, I'm distracting myself from CV sadness by finishing prep for my delivery in a few weeks. I don't have a nightshirt being a PJ person, but reading advice it seems that a short button down nightshirt is the best bet. As I can't go and try any on at the mo I'm going to order online, which i guess is the fact for all of us, pregnant or not! Anyway, advice is needed. I've seen a nice Joules nightshirt on sale - I'm usually a 10-12, should I get a 12 or 14? My bump is back to back so quite small although if the baby moves in the next 6 weeks I've been told to expect it to get significantly bigger! Or should I get a 16?
Thanks!

I'm usually a 10-12 and I bought a 14, but I guess it will depend on the shop how big they come up.

I would get the 16 as I hate tight things when trying to sleep and be comfortable.

Am normally a size 10 to 12 but got a 16 as 14 on bump fitted but would of been a bit snugg 16 so much better x