The 29-year-old actress and her husband Stephen Moyer - who already has two children, 12-year-old son Billy and 10-year-old daughter Lilac, from previously relationships - will welcome their first child together into the world this autumn, their representatives have confirmed to Entertainment Weekly.
Anna and Stephen, 42, met on the set of `True Blood` in 2007 and married in Malibu, California, three years later.
Anna has previously admitted she doesn`t find it strange having to shoot sex scenes with her spouse for the racy TV vampire drama.
She has said: "Maybe it should be weird, simulating sex with your husband in front of people. But it`s really not.
When it`s a love scene with someone you actually love it`s not, `Can I touch him here, can I touch him there?` You know what your boundaries are, or aren`t I suppose."
The actress is openly bisexual and has previously admitted she faces a lot of prejudice because she is attracted to both men and women.
She said: "Frankly no one had ever asked me about being bisexual before. There is a lot of prejudice against us but the more people talk about it, the less of a deal it will be. Who people choose to sleep with or spend their lives with shouldn`t matter, not that anyone particularly cares who I`m attracted to."