Nuala Conway, of Cookstown has given birth to the UK's fourth set of sextuplets at the Royal Jubilee Maternity Hospital in Belfast.
The four girls and two boys are reported to be healthy. Mrs Conway claims the six babies were conceived naturally, but fertility experts say she may have taken ovary-stimulating drugs that triggers the release of multiple eggs from the ovary.
Clifford Mayes, the neonatal consultant who was a part of the 30-member team that delivered the babies, said they were as healthy as could be expected. "It is an extraordinary thing to have witnessed but you are also struck by the fact that there are little babies in intensive care," he added.
Keith Reed, chief executive of the Twins and Multiple Births Association expressed delight at the news and said they would be hoping for the continued health of the mother and the babies.
"Around half of the 11,000 multiple births each year are premature resulting in one or more of their babies being cared for in a neonatal intensive care unit so our families understand the roller coaster of emotions this family will be on," he added.
According to available statistics, sextuplets are born only once in 4.5 million pregnancies globally.