spaying mum query

I woke up this morning to an almighty cat scream!

I went to check the 4 kittens, now 18 days old, and they were fine. I figured it must have been their mum. Anyway, she was downstairs at the door, peering through the glass at a very handsome black and white cat that was trying to scratch at the glass and get in. Obviously Tinkerbelle is on heat again and I need to get her spayed. Is it ok to do this with the babies being under 3 weeks of age? Or should I just keep her in for a few more weeks? I dont want her having any more babies!

Just keep her inside at all times with absolutely no access, even accidental, to the great (or not so great) outdoors. You can safely spay her when all of the kittens are eating solid foods on their own, usually by around 8 to 10 weeks old. They will still attempt to nurse, but by that time, Momma is no longer providing 100% of their nutritional needs and can be safely spayed.