Honestly, I'd clear it out.
See if you can find a charity that supports new moms with baby clothing and other items. We have a pregnancy center in town that takes these kinds of donations. Or maybe a women's shelter.
You should itemized what you're donating for taxes anyway - so you can write - 18 footed sleepers, etc. While doing that you can pick out the cutest/best condition stuff and save one or two totes for your siblings. They would be overwhelmed by 18 anyway and will want to buy some new things.