Hilary Duff has welcomed her third child, a baby girl, with husband Matthew Koma.The 33 year old took to her Instagram feed to announce the happy news with her 16.5million followers by sharing a gorgeous black-and-white photo of herself in a birthing pool cradling the newborn.The snap sees the star in a black top while husband Matthew, 33, strokes her head and her two other children Luca, nine, and two year old Banks stay close by.