I have had a few clients in the past both pre and post natal, and I’ve heard people say everything from fewer symptoms of pregnancy (less sickness, less swelling, less fatigue) to an easier / shorter delivery. As Joanne points out, it is very important to stay healthy and fit throughout pregnancy, as post partum isn’t a piece of cake. Doing a lot of posture work has been helpful, as post partum, there’s a baby to hold, along with the diaper bag and all the other toys, strollers, and other supplies necessary!
In a class setting, pregnant women (especially if it’s a class with other pregnant women) can also experience positive effects on their mental and emotional state. Having people to share with is important, as their significant others and friends may not be able to relate, and having people unrelated to ask advice from can also be very beneficial and comforting. Keep in mind that a mixed class, with very young or fit individuals could have a negative impact if there is any self-consciousness with the pregnancy.
There are no two pregnancies alike, so reminding the woman to listen to her own body is key!