What physiological changes will my expecting wife go through during her pregnancy? Anything I should be prepared for?

Lot of physiological changes and yes, u must be prepared to that as a husband. During pregnancy, husband support or help is very important to wife. Breast size increases. BP decreases during 2nd trimester & she feels week even for small household chores. And vomitings, dizziness, uneasiness, rib pain, neck pain, headaches may trouble her. Mood swings also influence her. Breath more deeply even at rest. Try to keep ur wife happy always because happy mother gives happy & healthy child. Good luck.