If I know I'm pregnant now (1month), how long do I need to inform the company? What if they terminate me? :(

Congrats!! If you have been with the company for over 6 months before finding out you were pregnant, they can't terminate you. I would advice to let them know as soon as possible so it's easier on you (no need to hide) and the company has ample time to find a substitute while you are on maternity leave.