Ashlee Simpson is a mum of three - after welcoming baby son Ziggy with husband Evan Ross.

The 36-year-old singer announced the happy news on her Instagram page on Saturday, sharing a snap of the newborn with her and Evan's hands rested gently on top.

In the caption, Ashlee revealed that baby Ziggy made his big entrance into the world on 29 October, as she wrote: "Ziggy Blu Ross. Our sweet boy has arrived! I'm over the moon, we are so blessed."

Hilary Duff, who recently announced she's pregnant with her third child, was among the celebrities offering their congratulations, as she commented: "Congrats guys!! Beautiful baby boy!"

Evan, 32, shared the same image of baby Ziggy on his Instagram page, alongside a slightly different caption as he commented "Our son has arrived. I'm in heaven."

Ashlee and Evan are also parents to daughter Jagger, five, while the Pieces of Me star shares 11-year-old son Bronx with ex-husband Pete Wentz.