How Rare Are Identical Triplets
Identical triplets occur when a single fertilized egg splits into three embryos. This is far rarer than identical twins. Exact worldwide rates are not well documented, but medical sources describe identical triplets as a very uncommon event.
What Causes Identical Triplets
Identical triplets can happen when the early embryo splits in two stages or into three separate parts. The timing and pattern of the splits determine whether the babies share placentas or amniotic sacs. Fertility treatments slightly raise the chance of multiple embryos, but identical splitting is not caused by treatment.
How Often Do Identical Triplets Occur
Exact statistics vary by country and study design. Some large registries report that identical triplets are a small fraction of all triplet births. For current global estimates, see the March of Dimes overview on multiple births at https://www.marchofdimes.org/find-support/topics/premature-birth/multiple-births.aspx.
