Heat for kittens

Question
I have an 11-month-old female kitten.  She has never gone into heat, and she has not been spayed (she lives with a 14-yr-old female cat and we live in a high rise, so since there's no opportunity for them to be outside, I didn't see the need).  Should I be worried about this?  It's been bothering me a bit to think about.  Thanks so much for your help!
                           ~Lea


Answer
This is very unusual and I would highly recommend having her spayed regardless if she can or can't get outside to get pregnant.  Spaying greatly reduces the risk of breast cancer in cats as well as eliminates ovarian cancer and life-threatening uterine infections.