Should i worry if my baby has got a small head? She is currently in the 10th percentile at 3months.

I wouldn't worry too much. Is baby developing normally? Achieving her milestones, eating, moving around well. If yes, you shouldn't be too worried. Also, it could just be hereditary -- do small head sizes run in your family? It's a wee bit too early to tell because baby's body is still growing. This does not mean they have a lack of intelligence.