nanny pregnant before we hired her

[mothered]

Help,
Our nanny has just revealed she is well into her second trimester. Was over 3 months pregnant when we hired her but did not disclose it. There were a few teething problems before this over trust etc. The problem is we have very demanding twins, 16 months, and she will be leaving them when they are about 19.5 months. She insists she wants to come back and will only take a few months off.
Questions I have are: *how are we meant to afford maternity pay and a temporary nanny rate (if indeed we are even liable) and
*how far into her last trimester can she work on health and safety grounds; right up until she drops?! If you are a nanny who has worked during pregnancy, what issues did you experience (I know everyone is different) and when did you stop work? Did you go back? I have very inflexible employers and work long hours. The reason we hired a nanny was so there were minimal days off due to childcare crises but this is already slipping as she has been off ill a few times.
*What should happens when our kids get ill with infectious bugs etc - we do not want to put her at risk obvs.
*And what will the impact be on our children of a temp after three months, or six months even if they then change back? What if the temp is more effective than the nanny and the kids have bonded with her? How vital a time is this age group for development etc? Friends have told me that I seem to be spending more time worrying about the nanny's rights than our kids'.
Advice appreciated to a pushover mum.

You would have to check it out legally but yes I think you could force her to start leave early if you did a health and safety assessment and found it in her best interest and your children's that she set an earlier date.
By the sounds of its probably because she needs the money, but that's not practical.

The kids I look after are 3,4 and 5 it's a nanny share and in 10 years of nannying the best job I ever had I am delighted that I will end my nanny career on such a high.
I'm not going back because I would have been redundant by about August as all the kids will be in full time school but would have done holidays.
We actually started to TTC hoping I would be pregnant by August I got pregnant straight away I was with them for about 18 months before I got preganant so they are genuinely delighted I'm moving onto the next stage in my life.

IMO it's easier having walkers/older kids because I can talk about it and they understand that they need to be more careful no jumping on me etc.
Plus it's a lot more physical with toddlers espically Twins, not matter how light the buggy is as they gets older and heavier it becomes really hard to manover the bugger even when not pregnant.
Your twins are only going to be getting more active meaning more running around after them as they go in opposite directions! I would point this out to her when speaking about leaving dates.

Just wanted to point out if you do hire a temp and it works out well then if your nanny decided not to return there is a high chance she would be happy to stay causing less disruption for your children. I know plenty of nannies who have found permant jobs this way.

I don't think you can force her to start earlier, though if she is off sick with a pregnancy related illness in the 4 weeks before the EDD, the maternity leave automatically starts then, otherwise the latest start date is the EDD.

Has she any accrued holiday by then, if so, maybe encourage her to take it off before starting ML (what does your contract say about who chooses holiday dates?)