Congratulations on the baby
I'm sure H&M has some comfy preggy casuals in their shop at the Centre Commercial Crissier (15 mins. from Lausanne)...maybe they'd have the same selection for moms in their shop at Metropole 2000.
There's also this little shop along the Gallerie St. Francois (one entrance of this gallerie is facing the Mango shop on Rue de Bourg, the other end is on Saint Francois ave.) where I saw some preggy outfits too.