How? Last triplet born four years later

MCKINNEY, TX - Little Andrew was recently born a triplet, but the oldest of the three in Texas is already four years old. How is that possible?

His parents, Chris and Joyce Mallon, had the three conceived in a petri dish back in October 2007.

Julianna is the oldest and was born through in vitro fertilization nine months later.

Next was AnnaSophia, followed by Andrew four years later.

"Sometimes when you pray for a miracle, you get three. And so that's what we have," said mother Joyce.

She calls them "triplings," since they are triplets by conception but siblings by their dates of birth.

Fertility experts say freezing techniques have improved, so embryos can now be preserved for longer periods of time.

An estimated 400,000 embryos are currently in frozen storage in the United States.