Just a few photos.
I like to do some photos in the studio as well. This was taken with a gray backdrop, the parents-to-be were about four feet in front of it with the flashes only two feet from them. Both flashes had large softboxes, and the flash on the left was set slightly brighter.
I also always include a prop or two with maternity sessions, so that when the parents return with the newborn, I can reuse the prop. Sometimes I’ll continue using the prop throughout the first year, and depending on the prop chosen, at subsequent birthday sessions as well.
Another fun effect for maternity sessions is to place the large softbox behind the couple/mother. Sometimes I’ll set the exposure really dark and turn off the other flash to get a full sillhouette. Other times, I’ll go for something like this. The second flash is to my left.