I didn't tell my mom I was pregnant until I was almost 3 months pregnant ... Of course she will be upset & angry but obviously it doesn't do any good to keep it from her. I was 15 when I got pregnant with my daughter & had her 3 months after my 16th birthday . The best decision I ever made was telling my mother I was pregnant because no matter how hurt, disappointed, or angry she was, she still had my back & was very supportive through out the whole pregnancy. My daughter just turned 4 in August & their relationship is so strong. You never know how she is going to react, but all you can do is hope for the best but prepare for the worst. You have to tell her eventually. Better now so she will have time to come around to the fact that you will be having a baby .!