The yoga breath is a powerful tool to aid in decreasing muscle pain and discomfort caused by pregnancy.  As you work into a yoga posture imagine your breath going into the tight muscle creating space.  Imagine with each breath your muscles becoming more supple, longer, and agile.  See below to perform the yoga breath.

Yoga Breathing
The yoga breath is performed by inhaling in through your nose and exhaling out of your nose with your mouth closed.  As you exhale press your tongue on the roof of your mouth.  You should hear your breath loud in the back of your throat.  Begin practice by sitting comfortably.  Focus on your chest and belly expanding as you inhale, and notice your chest and belly compressing as you exhale.