How do I tell my sister.

Long story short. I'm pregnant and kinda scared to tell my older sister cause I don't want to hurt her feelings. After her marriage she and her husband started IVF (cause she had cancer and carries the gene). Unfortunately the marriage did not work out and she is now a single 36 year old without children. I know the wants children, but she is very traditional so she will never choose to have them on her own. So now she is a little bit depressed and scared that she will never have kids. How do I to tell her that I'm pregnant. I feel like I have so much more luck in my life than she has and I don't want to point that out. I do want to make it a special announcement, but I do not know how she will react.