Yes Kraemer do them, called 'PregnaBreeches' - go on the Kraemer website (www.kraemer-pferdesport.de) and type 'pregna' in the search box. However it says something like 'ride till 6 months' so maybe not big enough if you are already 6 month pregnant?!
I have a couple of pairs of those Shilasflair but the waistband goes across the middle of bump and is uncomfortable now and if I push them under bump then they work their way under bum too!!
I just bought some cheap extra large jods & with the help of a belt expanded them as necessary. I still laugh when I come across them in my wardrobe!
I was huge when I was pregnant and I found the most cofrtable thing were these leggings they did for male runners. They had great wicking, were very snug and expanded nicly aroudn the bump. However, they were see through so I had to wear very long t-shirts!
I had some Harry Hall endurance jods that were a sort of cross between a trakkie bottom and a jod, with a drawstring waist - I am pretty sure they still do them. Anyway, they did me through my pregnancy - I have a picture of me in them somewhere, with a big bump