should I tell my parents?

I'm 7 weeks pregnant and it's getting harder and harder to hide my morning sickness and extreme fatigue. I have a 2 year old toddler and live at home. My parents would not be against it but just extremely worried since my first pregnancy was full of complications. I want to be able to talk to them but I don't want to cause them any added worries since my older sister is also pregnant and high risk as well. My mom is already concerned and stressed over her pregnancy