Random question about the mirena coil

[BeyondTheLimitsOfAcceptability]

Had it fitted last week for the first time.

Curious though, if I still have periods on it, will they be on a 28 days cycle like the pill, or my own natural cycle (which is 21 days)?

That's an interesting question. All sorts of random minor spotting for me, after ongoing slight bleeding for a while after it was put in.