When I was pregnant I decluttered my prepregnancy wardrobe and got rid a few things. I held on to a lot of my prepregnancy clothes, a couple garbage bags in the back of my closet. It took several months after I had my son before I fit into my prepregnancy clothes again. I took a few things out here and there that I was so glad to have, like jeans that "fit" and looked good on me. Meanwhile, my nice jackets and many of my shirts took several months more to fit. I'm glad I didn't toss them, though, deciding they wouldn't fit my new mom figure, as now they look great on me. There are some shirts that were a little small to begin with, that especially don't fit me now, even though I'm below my prepregnancy weight.
Recently I decluttered my entire closet and dresser, keeping only what currently fits and a few select "in between" items that I really loved having this time around: a few pairs of jeans that I felt really good in. I figure that as long as I have some basic pieces I feel good in, I can pick up a few complimentary items fairly cheaply. It's important to feel good about oneself in that "in between" stage.
I do have a bag of maternity clothes saved for future pregnancies.