Hi,

Well gynaecology and obstetrics is a course under Medicine. You won't get a Msc degree in it. You will get a MD or a MS in it and the same reason because of which you can only do that after a mbbs and not after a bsc. If you want to become a gynaecologist then you need to follow the mbbs and then me track to become one.

I hope my answer helps.

All the best.