Advice on company changing my days and hours. When a. Pregnant and b. Other childcare issues

[Mum2oneds]

So my employer rang me today.. Whilst I'm off sick may I add. And said she's drawn up everyone's new contracts to start in Sept. Now I said I can't do what she needs due to my DS and I've also heard that changing hours is classed as changing contract conditions... = they can't without mutual agreement when pregnant.
It was too late to ring acas so will tomorrow.
I. Fuming as I have already told them I can't do this, and to ring when I'm off sick pregnancy related too takes the piss.

Now although I know they can change people's hours to suit the company needs. I have read that they would have to prove there is no one else whatsoever that could do that day instead of me.. There's 25 in our dept too and im the only one with a child..
Just can't sleep stressing about this.. Dp has gone nuts telling them to stick the job.. But it would be silly to because of mat leave. But defo going to leave at earliest point now rather than help them over Xmas.

It depends on what your contract says. If your hours are specified they cannot change them without agreement.

Even if they aren't you potentially have a claim for indirect sexual discrimination if they are unable to show that the change is necessary and no other option is available. Given what you have said about there being 25 other people you probably have a good argument on that basis.

ACAS are great for advice on these types of things

Yeah I do set hours which are written down. Thank you.