IF you go through with the courthouse wedding in Minnesota, then there is no need for another ceremony in Hawaii. YES, any other type of ceremony (after a courthouse wedding) would be a "vow renewal."

I am NOT trying to sound mean, but if you are living with his family while you are pregnant and he is working to save money……DON’T go to Hawaii! Hawaii is NOT cheap by any means. Just the flight from Minnesota could be $1,000/each…then a wedding….then a honeymoon! Not a good idea.

Why not look more locally. Really, I live in Michigan so we have most of the same weather you do in Minnesota. The fall is really pretty. Why not (just the two of you) look into going somewhere more locally. Look into going to a Bed and Breakfast Inn or a historical site and have your wedding. Have you thought of the North Shore of Minnesota? There are so many nice lodges, hotels, resorts up there that provide weddings. Here is a link I found:
http://www.theknot.com/co_profileview.htm?profilename=NorthShoreMN
http://www.caribouhighlands.com/groups/weddings.htm
http://www.resortsandlodges.com/lodging/usa/minnesota/north-shore.html
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We were married legally before our child was born, and now, since we have some extra money and are over the "baby" thing, we are having what’s called a "Validation Ceremony". It’s basically a wedding without the legal part of it. You can be legally married and enjoy the tax benefits now, and when you have some more time and money you can have a real wedding. It will be different and you will be treated differently by some people, but that will all go away when your dancing in your wedding dress holding your son/daughter and your husband. Believe me, wait, enjoy your newborn, get your figure back and have a wedding when your lives are a little less hectic.

Oh, and a bonus- since you’ll already be married legally, you can have anyone perform your validation. My dad is "marrying" us. So sweet.
References :
Baby before the wedding!