My week-old premmie baby had a blood transfusion

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My darling son - born at 26w & 1d - had a blood transfusion last night.
We had been told that this isn't uncommon at all with premmie babies, and he's doing really well now which we're grateful for of course.
I was fine when we were told a few hours ago, but the thought of it is overwhelming me a bit now & I'm teary.
I could use some words of comfort please.