If you only have swelling in one side it's a good idea to get it checked by your doctor in case of blood clots. I have 1 leg that has been swelling since about 30 weeks (I'm 38 weeks now), and Dr said it's because I favor that leg when I stand at work. He made me wear compression stockings and cut back on working, keep my feet elevated, drink water and rest a lot. Are you on your feet often? Also, because your baby is so large he could just be pushing down harder on one side causing more swelling in that leg.My baby is also thought to be a big baby and my Doctor said that could be a factor.