I'm on 3rd pregnancy and got SPD mildly at about 38 wks (it ended up being a 42wk pregnancy) first time and then 35 weeks with second (also went over to nearly 42 weeks). I spoke to MW about it at 35 wks the second time but there was a 6 week wait for physio so no point. I can feel twinges now at 26 weeks but nothign too bad. Is it worth asking for a referral now just in case? Does it really help?