Dd has period only 3 or 4 times a year? Possible reasons

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Daughter is 18, started periods at 12/13 but has only ever had one every 3 or 4 months, she's not overweight, fit and healthy, but I'm worried about what it could mean if anything. Is this something you would see a doctor for? She is pleased she doesn't get them regular and when she does it's very light and only a couple of days.

Could be polycystic ovaries, you don't have to be overweight. I'd see the doc.

This was exactly me. Started at nearly 13 and had 3 or 4 a year and they were very very light.
There was no reason for it at all and I had no problem getting pregnant, it was after the first baby at 24 that my periods regulated and I got one every single month without fail.