Running Away, First Book of the Rhia Series.

Rhia Timore lives in the future, a future where there are too many people and not enough space. As a result, families are allowed one child and one only, if they have another, both the mother and the 'Extra' baby are sentenced to death. Surprise, surprise, Rhia is an 'Extra', and has seen many of her kind killed. When the government decides the house she lives in is not space-efficient, and decide to knock it down, Rhia has to run. And run fast. Because they will always be looking for her, and all the others, to take away her right to live, love, but never her hope.