Do I need to take vitamin B12?

[Serenissima123]

I'm currently 6 weeks along, and I've been taking the recommended amount of folic acid and Vitamin D supplements. I read in "What to Expect" that we might also take B12... but I see it's not listed as a requirement on the NHS website. Should I also be taking this? Autism is very prevalent in my family, and I read somewhere it can prevent autism, not sure if it's true though.
Do you/did you take B12?

No. There’s no need unless you have been told to by a doctor and you have symptoms of a deficiency

You can take a pregnancy multivitamin to cover all.
Unless you are having frequent blood tests you will not know if you develop deficiencies.