I just finished two baby projects - a hooded baby wrap and a larger blanket. I've done lots of these over the years and I always wash them before giving them as gifts. After all, a new mom might be pre-occupied enough with other things and skip washing your gift before using it.
I machine wash the acrylics with a half measure (or less) of liquid Ivory Snow in warm water in the machine. If I put it in the dryer I use a delicate setting (heat tends to take the elasticity out of acrylic) but mostly I take the item and stretch it on my blocking table. It's amazing how beautiful the finished project is once washed and blocked.
But at the very least, I'd definitely give the blanket a wash.