Hilary Duff has already chosen her new baby's name.

Hilary Duff

Hilary Duff

The 'Younger' star is due to give birth to her little girl, whom she's expecting with her boyfriend Matthew Koma, later this year but revealed that the pair already know what they want to call the tot.

She told PEOPLE: "It was the very first thing [we decided on. We've known her name for a really long time. Her name starts with a B, and I keep calling her baby B, which is awesome because people are like, 'Oh, no, it's just because of his last name.'"

Koma's birth name is Matthew Bair.

Hilary, 30, also revealed that pair were torn between two names but are now thrilled with their choice.

She said: "We actually agreed. We had one name picked out and then we swapped a week later and we haven't discussed it since.

"It's unique but it's not too weird. The name that we first thought we were gonna use is going to be her middle name, so we're like, 'Let's not stress over this anymore.'"

Meanwhile, Hilary - who already has six-year-old son Luca from her marriage to Mike Comrie - previously admitted she is finding this pregnancy "hard as hell".

She wrote on Instagram: "The boobs are big the belly is big the body is big. Man.. pregnancy is hard. Giving love to all mamas who make it look effortless... this journey is hard as hell and also incredibly special. Lovely to have a little life inside and to day dream of all the new adventures to come buuuut almost impossible to get my own shoes on..sick of getting up 9 times a night to pee and looking at this weird body in the mirror that is not my own at the moment. (sic)"