Hi all
If you are 20 weeks+ you can sit in first class if you apply to Southeastern (when no other seats are available).
I did this when pregnant last year but spoke to a lady on the train last week who didn't know this so thought I'd share.
You need to send a copy of your matb1 or a letter from midwife and they send you a letter back authorising it up until your last working day before your due date.
Definitely worth it if you are travelling in rush hour.