The American Pie star became a first-time father in February (14), when Mollen gave birth to baby son Sid, but they have since revealed it wasn't the first time the actress had fallen pregnant.
The new mum admits they almost became parents in 2008, just weeks into their relationship, but she tragically lost the baby at 12 weeks.
She tells People magazine, "It was odd timing, but the (miscarriage) bonded us in a crazy way.
"That was when I knew, if I'm willing to have a child with this guy, he's the One."
The couple decided to elope two months later and wed in April, 2008, and Biggs and Mollen credit weekly therapy sessions with helping to keep their relationship on track.
Biggs says, "Everyone should be in therapy. And when things are good, that's when you get the most work done. That's when you're open to hearing and learning to communicate better."