Kalie and Joshua Kuhl welcomed identical triplets Tuesday in Rockford, Illinois.

If that wasn't rare enough, the boys' survival was complicated by an unusual womb disorder, reports the Rockford Register Star.

The complication was twin-to-twin-to-twin transfusion syndrome, which happens when the babies share the same placenta and some of the same blood vessels, according to the newspaper.

It is a dangerous condition because one fetus can be overloaded with blood and amniotic fluid and cause heart failure, while the other fetuses are deprived, according to the Star.

The babies are being closely monitored at Rockford Memorial's Neonatal Intensive Care Unit.