Game Of Thrones star Lena Headey has welcomed her second child, a baby girl.

The 41-year-old actress, who plays the role of Queen Cersei Lannister in the hit HBO series, took to Twitter to share the good news.

"Hello peeps. All good. Just fallen in unconditional heartbreaking divine love for the second time," she wrote.

The 300 actress is mother to four-year-old son Wylie, who she gave birth to while married to musician Peter Loughran. They divorced in 2011.

Headey, who announced her second pregnancy in February, is yet to share the identity of her daughter's father.

Meanwhile, in May, in a blog post titled My Daughter for the charity Plan International USA, Headey publicly declared that her unborn daughter would be free to love another woman.

"I am having a baby girl in six weeks. You have all been so lovely in your messages to me, and I thank you for that," she wrote.

"My daughter will have freedom of choice. She will be free to dance, to sing, to be educated in the fields that spark her passion, to marry if she wants, to marry WHO she wants, to remain single, or to fall in love with another woman. She'll be able to wear what she wants, put on lipstick, and read books that spark debate and expand her mind.

"She will be loved, protected, respected, and celebrated," she added.