The heavier and larger your belly gets, the more your internal centre of gravity shifts.
This will likely affect your posture and lead to pain in the lumbar spine as a consequence. Pay attention to your posture and try not to slouch. For some women, their sex drive decreases or disappears at this time, as a result of the changes to the body. In some others, they might witness an increase, due to the increased blood flow in the pelvis.
You may need iron supplements to boost your vitals. Your midwife should be able to advise you accordingly after your regular checkup.