Updated — May 12, 10:22 a.m.

Ohio mom Sarah Thistlewaite got a special early Mother's Day gift when her rare identical "mono mono" twins were born healthy on Friday.

The twins, named Jenna and Jillian, had the rare condition of being monoamniotic, or "mono mono" identical twins, which means the fetuses share an amniotic sac and remain in near-constant contact for the duration of the pregnancy. The mono mono condition occurs in about 0.3% of births.

Thistlewaite, who has a 15-month-old son, was on bed rest at Ohio's Akron General Medical Center for nearly two months, where doctors could monitor the babies' health, as the siblings can often become entangled in each other's umbilical cords.

"It's really mentally challenging. It's a very tough experience to go through," she said.