Sarah Michelle Gellar has wished her daughter a happy birthday.

Sarah Michelle Gellar

Sarah Michelle Gellar

The 39-year-old actress took to Instagram on Monday (19.09.16) to share a heartfelt picture of her daughter Charlotte, now seven, as a baby being held in a smiling Sarah's arms.

The caption read: "Sometimes when I need a miracle, I look into my daughters eyes, and realize I've already created one #happybirthdayCharlotte #thisis7 (sic)"

The former 'Buffy' star - whose four-year-old son Rocky also has a September birthday - has been planning a mammoth party for the pair as she also took to Instagram on Sunday (18.09.16) to share a picture of her car full of balloons ready for the celebrations.

She wrote: "This is me trying to drive home with a car full of balloons I apologize to anyone behind me while I was driving 5mph (my sight was slightly impaired) Two kids, two birthdays...these are the things we do. No #momfail on this one. (And yes I pulled over the pic..what kind of crazy driver do you think I am??) (sic)"

And it seems like September is the month for celebrating for the family, as at the beginning of this month Sarah celebrated her 14th anniversary with husband - and father to her two children - Freddie Prinze Jr.

Sarah - who met the fellow actor filming 'I Know What You Did Last Summer' in 1997 - posted on Instagram to share their anniversary with her fans.

She said: "Happy anniversary @realfreddieprinze You stole my heart, so I got my revenge and took your last name!! (sic)"