Hilary Duff's son Luca is ''on the fence'' about having a baby sister.

The 'Younger' star - who is expecting a little girl with her partner Matthew Koma - has revealed that her eldest child, her six-year-old son, isn't too keen about being a big brother.

She said: ''He's on the fence, but I think that everything will be fine when she arrives.''

And the 30-year-old actress is ''so excited'' to welcome her little one.

She added to The Today Show: ''Everything is good. I'm ready for school to start I think like every other mom. I'm looking for a little more structure right now ... In this late stage, you're tired of running around and stuff, but we're ready. I'm so excited.''

And Hilary can't wait for her daughter to arrive.

She wrote on Instagram recently: ''Can't help but imagine this little girl is growing and blooming in my belly like these roses that keep popping up at our house. Pregnancy is filled with so much emotion and some really tough long days but it sure is special. Feeling lots of love today with every movement and kick to the bladder lol. Appreciate that this one picked Matt and I to be her mommy and daddy. We gunna crush it for you baby B. You also have the sweetest big* brother waiting to meet and love you (sic)''

The blonde beauty previously admitted she is finding pregnancy ''hard as hell''.

She shared: ''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)''