With my first pregnancy I took my regular yoga class until my belly got in the way.  I don’t recall doing anything more than walking after that.  My husband was unemployed during my entire second pregnancy, which ended up being a good thing for my body.  We went to the gym together, a lot.  My belly and I lifted weights and walked on the treadmill.  It was good for all three of us.  Here are some classes the moms recommend for pre-natal and post-natal exercise:

Evergreen Yoga
Midtown
Pre- and post-natal yoga, mommy & me yoga
I loved the prenatal yoga class at Evergreen Yoga.

YMCA Shilling Farms
I have really enjoyed the gentle/restorative yoga classes taught by Andrea at the YMCA in Collierville. Not specifically prenatal but Andrea is extremely knowledgeable about what you can and shouldn’t do while pregnant. They also have a saltwater pool which is great for swimming which is great while pregnant.

Pure Barre East Memphis | Germantown | Collierville
It’s low impact and the instructors have modifications for each trimester. Just tell them when you start that you are expecting. I’m 20 weeks and have been going. Also great post baby!

Fusion Fitness
Bartlett
pre- and post-natal exercise classes

Fit4Mom
Stroller Strides classes you take with your baby

Kroc Center
Fit Mom and Me classes geared towards moms-to-be and moms with babies ages 6 weeks – 6 months.

Sumits Yoga
Germantown
Taught by Susan Wilcox

Trillium WomenCare
Midtown
Prenatal and postpartum Pilates

Delta Groove Yoga
Overton Square
Mommy & Me yoga, prenatal yoga and kid yoga for ages 3-8

Dance Academy of Bartlett
Will begin offering adult classes this fall incuding Bootie Camp (for pregnant moms) and Baby-carrying fitness

Memphis Botanic Garden
Baby & Me yoga classes