chihuahua pregnant after 1st heat

Question
My 10 month old chihuahua was recently in her first heat and I came home to find her knotted with her father. She is petite and young,I am worried about her health and the health of future pups.Bella weighs3.5-4 lb. and her father is even smaller, do you think her and her pups will be O.K ? I assume she is pregnant because her nipples have gotten alot larger. Thank You

Answer
The problem with inter-breeding, is that the if you have ANY hereditary problems, they will be pronounced in the pups.

Also, consideration for her age should be given.  A mentally and physically immature female can reject her litter.  However, Chihuahua mature quicker so make sure you are feeding adult food so the pups don't grow to large.