both are 安全. 全麻 mother will feel a bit uncomfortable whe she wakes up and normally would vomit/throw out. if u can choose, 半麻 is better because u can see the birth of your BB.
I was a 緊急 case at QM 4 mos ago. The doctor suggested 半麻, as it is safer than 全麻. But I chose 全麻. The doctor had to know why as she said very few people choose this. I said I was just too scared.
In my case I'm glad I chose 全麻 because when I was on the operating table, I was so scared I was shaking really bad and was crying. Afterwards, no vomit, but my left leg still a little numb (4 mos later). So it's different with everybody. But if you're not scared, is yr 2nd time, and you're even willing to go natural birth, I suggest 半麻.