My Midwife told me that if you get it you will to some degree get it in subsequent pregnancies but the severity of it depends on the age gap between your babies.
If you have a bigger gap your body has more of a chance to recover.
I had wicked SPD with son number two as number one was only 11 months when I got pregnant again.
With number three it was tolerable because the gap was well over two years between pregnancies.
With number four I hardly noticed any problems but that gap was 5 years.
This time around I have it again quite bad but my gap is alot closer again, under that magical two years.
SO I believe the longer the gap the better your SPD will be.