Adopted kitten is pregnant

[GRW]

Just before Christmas I visited a relative 250 miles away, who persuaded me to take a tabby kitten he had been given but felt he couldn't look after due to being at work full time. She is about 7 months old now, and is a lovely gentle little thing.
I took her to the vet today to start her vaccination course, and she was booked in to be spayed next week. The vet found she is already pregnant, and whilst I don't want to add to the unwanted cat population I don't feel I can abort kittens that are on the way.
I've been told she shouldn't be vaccinated whilst pregnant, and I will get her spayed as soon as possible after the kittens are weaned. Does anyone have any tips about looking after her during and after the birth? She is still a kitten herself and only weighs 2.6kg, so I am shocked that she is pregnant although she was allowed outside when my relative had her. I will obviously keep her indoors until she is vaccinated, spayed and microchipped.
We have 2 other cats aged 18 and 10, and I haven't any experience of having newborn kittens.

I would have thought giving birth so young would be very risky for her. Personally I would go ahead with the Spey for her sake

Try to get over your feelings about abortion. It would be best for her and best for the cat population in general. Giving birth is risky at the best of times, and for very small, young cats, it's even worse. And there are just too many cats and not enough homes. Even if you manage to find homes for your kittens you will be taking away homes that could have gone to other cats or kittens in need.

She can't be far along if you hadn't even noticed. Do it now and it will be the best thing all round.

It's going to be dangerous for her to give birth. She's still a kitten herself. I don't think you should do this. Having taken on two rescue kittens who are now 6 months and due to be neutered/spayed next week, I've thought about this issue a wee bit, just on the off chance they both suddenly sexually matured before their apptmnt. I know I'd abort in a heartbeat because I couldn't put her at risk like that. She too is very small, and she's had a traumatic past. She came from a kitten farm and I took her on specifically to prevent her being made to endure birth at such a young age.

Have to agree with the above. 7 months is too young to be having kittens.

May I just add, under thecatneuterers beady eye that the only reason it wasn't done sooner was a combination of my finances, the vets standard policy of doing it at 6 months for both males and females, Buttons size and the fact that they go in to the vets every 4 weeks for flea, worm and weigh so she's been keeping a beady eye on Pumpkin and monitoring whether he was looking sexually mature yet.
I'd have done it sooner if necessary.

As others have said, her health and wellbeing has to come first. It's akin to a pre teen giving birth - dangerous. You will possibly end up with huge vets bills and no cats otherwise.

Thanks for the replies. The vet did think she would be big enough to have the kittens, but I haven't cancelled the spay appointment, and I do want what is best for her. I wish I had her younger and would have got her spayed as soon as she was old enough.