I am not sure I would designate the shower to both. Most guests will only bring one gift anyway. I would try to incorporate both in the poem/phrase on the invite. Maybe have a rhyme on the invite that has both coming to see the happy couple's 'new baby' and 'new home' in it. Something like, "please stop by to see the happy couple's new home where their new family will begin. come and help them celebrate and settle in!" You can also google sayings for showers and house warming, etc then blend them to match and rhyme. The hosts throwing the party should add something about where you are registered for the baby and also coming to see your new home. If you are wanting gifts for both, you may want to have two separate parties. I would suggest you having your own house warming party. You could have a cookout and invite close friends so as not to imply a gift. Most ppl will bring a bottle of wine. You could have a wine and cheese party and tell each guest to bring a bottle of wine to share. You could have a stock the bar party and they all bring a bottle of their favorite beverage. Then, closer to time, your girlfriends host a baby shower for you. You also want to keep in mind that there may be some ppl you want to come to your baby shower but not to a house warming, or visa versa. Have the baby shower during the day and the housewarming at night. For our shower our friends had a couple's shower for us. It was an evening cookout for couple's so my husband was involved too.
If you want to incorporate and think your friends won't care to bring two gifts, have the hostess write where you are registered at the bottom. ex: Babies R Us and Home Depot then maybe you get gift cards to each.
For my second child I did not want another shower so what I did was have a 'sip and see' where AFTER my daughter was born I had a brunch for friends and family to come have brunch and meet our new daughter. Of course they brought a gift anyway but I was able to be relaxed, have it in my own home, let everyone meet her on my own time, and me choose my own menu and entertain my friends all in one party!
Congrats to you both! W.