Hi Susan, A very good exercise program, especially if you are having mobility problems, is Essentrics / Classical Stretch developed by Miranda Esmond - White a former dancer with the National Ballet of Canada. (unefemme.net)
A good exercise program can really help in your second trimester. (mypregnancyguide.com)
What factors are important for choosing the best exercise program for each, individual woman in her 40's or 50's? (integrativewomenshealthinstitute.com)