But those helmets are there for a very serious reason — the 6-month-old triplets were born with craniosynostosis, a rare birth defect that causes a baby to be born with an abnormally shaped head.

But in babies with craniosynostosis, a serious birth defect that occurs at a rate of around 1 in 2,000 births, these bones fuse prematurely, preventing normal brain development and leading to mental ...