What do you mean by irregular periods??
Like, you miss some periods or they come whenever they want?
I would go through some months where I would have irregular periods and what I mean by this is that I would get my period maybe twice a month or so for a few months and then it would go back to regular for a while.
While I am on my periods "regularly" I will have it for 7-8 days. I am 3 months pregnant now and even though I have been having bleeding for 2 and a half months it is slowing down alot now. Some days I won't bleed and some days I will just spot. As far as my last ultrasound shows my baby is still growing at a normal rate.