I had spd to a certain extent in my first pregnancy, worse in the second and worse still in the third pregnancy. I don't think I had a very good physio third time round: she basically gave me a belt and told me to stop doing things that were keeping me fit (but bad for the spd) like walking everywhere - but didn't give me anything to take their place. I already knew all of the standard stuff like keeping your legs together when getting out of a car, keeping a pillow between your knees in bed blah blah. But I had hoped to get a bit more help from the physio and it wasn't really forthcoming. I had a terribly long transition when ds3 was born, probably because my pelvis was misaligned and it took a long time for his head to rotate around. And I had really bad pains down the outside of my thighs, which stayed even in between contractions. I think the combination of having been fairly inactive during the last few weeks, and my pelvis being misaligned, made that labour quite difficult.
This time round I had a brilliant physio who gave me loads of exercises to do: some core strength ones and some stretches (particularly for my glutes and hamstrings as they were getting very tight from overcompensation when I was walking). Not only that but she did some physical manipulation to move my pelvis back into alignment.
I was very diligent about doing the exercises, cut down on walking around and carrying heaving things, but I went on the exercise bike nearly every night as she had said that would be okay for the spd. Also I had been diagnosed with gestational diabetes and was trying to manage my blood sugar levels with diet and exercise alone.
I first saw her at about 26 weeks, went back at around 34 weeks and she found my abdominal muscle separation had hardly increased at all, so I was very pleased with that.
I started seeing a traditional chinese medicine practitioner at around 34 or 35 weeks, mostly due to the diabetes, but she did some acupuncture for the spd later on as I did start getting some sharp pains towards the end of the pregnancy. I was sceptical about acupuncture beforehand but feel that she did make a difference.
After all this I went 'overdue' by 5 days and still felt so much fitter and healthier than I had done the last time! The spd was really not a problem during labour.
So I would definitely recommend finding a good physio - one that can give you lots of exercises to do and help you to stay fit. And possibly going for acupuncture towards the end.