So H&M have restocked their thick "heavy" leggings!
I have been waiting for these to come back for so long as they are nice and thick almost like sweatshirt material and they are more supportive on the bum than the regular thin ones. They fit nicely below the bump or over if you go a size up! They're a bit pricier at £8.99 but still a total bargain!
I bought 3 pairs in store (Bath). No sign of them online yet tho!