Monoamniotic twins or often referred to as "Mono Mono" are identical twins who share both a placenta and an amniotic sac, but have separate umbilical cords.

Basically, the twin babies share the same living space while in the mother's womb. This type of pregnancy is incredibly rare and happens once in every 10,000 births, according to experts.

Mono Mono can be detected by ultrasound prior to birth when no membrane between fetuses are present. There several health risks for monoamniotic twins due to the closeness within the amniotic sac. Mothers with Mono Mono twins are kept under frequent fetal monitoring.

A recent study titled, "Monochorionic Monoamniotic Twins: Neonatal Outcome," concludes " Monochorionic monoamniotic twins remain a group at risk for cord entanglement, congenital malformations, TTS and prematurity. Although their neonatal mortality and morbidity is high, outcomes for survival are better than anticipated."

The recommended delivery period is somewhere between 32 and 34 weeks as cord accidents may occur at any time. There is a consensus among physicians that during this stage available neonatal care must be provided so that mono mono twins delivered during this period have a good chance of survival. Birth is usually done by cesarean section considering in vaginal delivery there is an increased risk of cord accidents.

A Mother's Day Gift

On Sarah Thistlethwaite from Ohio delivered a rare "mono mono" twin girls, Jenna and Jillian, who were holding hands during birth. Born at the Akron General Medical Center, the Associated Press reported the sisters were finally taken off ventilators Sunday afternoon, Mother's Day and were held by their parents Sarah and Bill.

Dr. Melissa Mancuso, who helped delivered the twins, shared Sarah's pregnancy held only minor issues.

"It's just hard to put into words how amazing it feels to know the girls are OK," the doctor said.