Niamh O'Sullivan has welcomed her first child

The new mum announced the arrival of her baby girl on Instagram last night.

Alongside a sweet video of her baby's hand moving, the proud mum shared her news.

She captioned the video, "She’s here & she’s perfect."

Niamh also revealed the name of her baby girl in the announcement post.

"Our precious baby Isabelle," the new mum wrote.

The name Isabelle is of Hebrew and French origins and means 'God is perfect.'

The charming name is such a beautiful option and the most elegant name for a baby girl.

Niamh's followers showered her with loving messages following her touching announcement.

Louise Cooney wrote, "Awww Niamh she’s finally here. Huge huge congrats to you both. I hope you’re feeling good, enjoy every second of her."

Niamh Cullen added, "Most amazing news biggest congratulations."

Katja Mia shared, "Congratulations Niamh. Enjoy all the newborn snuggles."

Holly Carpenter said, "Congratulations Niamh! Welcome to the world Isabelle."

Niamh revealed she was pregnant with her first child in February.

The new mum posted a montage of her pregnancy journey to announce the special news earlier this year.

She captioned the video, A dream come true. Baby Butler coming this summer."