It will be once a month bby check up till 36 weeks. Subsequently will be 2 weeks/1 week till EDD/labour. If they are concern more on your fibroid, then you should ask them how's the routine check? Is it gonna be once a month or twice a month? Though they dont have list but they should explain if this check will be for your fibroid or baby.
Actually visits before n after 20 is monthly.. only later part i tink wk 32 time it was 3 wks or what then weekly