A Canadian girl and boy born over four months premature and not expected to survive have celebrated their first birthday with a Guinness World Records nod as the world's most premature twins.

Adiah and Adrial Nadarajah were born on March 4, 2022 at the gestational age of 22 weeks, or 126 days early -- breaking by one day the previous record set in 2018 by American twins.

Weighing just 330 grams (0.72 lbs.) and 420 grams (0.92 lbs.), respectively, they are also the lightest twins at birth ever, Guinness World Records (GWR) said on its website.

Citing the babies' parents, the reference book for records of human achievements and natural world extremes said the twins were given "zero percent chance of survival" by doctors when they arrived.

"When I went into labour, the babies were denied all life-sustaining measures at the hospital I was admitted to and almost left to die," their mother, Shakina Rajendram, told GWR.

Most hospitals do not attempt to save babies born before 24-26 weeks.

But these two are alive and kicking.

A photo of the twins sitting on a couch next to their GWR framed certificate shows Adiah looking surprised with her mouth wide open, while her brother Adrial appears pensive.

The twins were described as having been extremely thin, with transparent skin at birth. After a six-month hospital stay that saw doctors dealing with several complications including brain bleeding and sepsis, they were finally sent home.

Since being discharged, according to GWR, Adiah has grown to 18 times her birthweight. "She's an extremely happy and social baby, and smiles all day long," Shakina said. "She is very chatty and has 'conversations' with us and her toys for hours."

Adrial has suffered a few setbacks -- infections and respiratory issues that sent him back to hospital twice for care -- but is said to be "progressing well."

Shakina described him as "observant, attentive, and intelligent," and a music lover.