We have been having these (call them what you will) for all the pg moms in our Natural Parenting Group. We have a LOT of moms due in Aug/Sept, so we're having about one a week in August, lol!
Everyone brings a prayer, poem, blessing, or what have you with some words of inspiration for the new mom. Our group tends to like to paint henna on the new mom's belly. We have had a professional henna artist come, but most of the time everyone just dives in and adds some part of the decoration. We bring good food, and spend time just talking. Our Blessings are generally done with moms and babes-in-arms only. Dads get to watch the older kids.
Then there is usually something special planned, and we tailor this to mom's needs/wishes and her personal beliefs. For one mom, we passed around a lit candle and everyone gave their tips/words of inspiration. Then the mom kept the candle, and could light it as a focus point during labor, and remember all the women who were with her in spirit, encouraging her. We also all held onto a circle of string, and said a prayer, then we cut the string into bracelets/anklets for each of us, and kept those to think/pray about the mom & baby until labor... the idea was that labor would come as the strings wore down and fell off. But, please note, don't use hemp! It took forever for those to wear off, and this mom went to 43 weeks!
For another mom, we made a "recipe box" for a peaceful and gentle labor, birth, and postpartum. Everyone wrote their "recipes" on an index card, so mom could pull out some encouraging words at any time she felt the need. The categories for the recipes were: Practical Tips (like sitz pads for pp), Inspirations (appropriate scripture passages or affirmations for labor), Heart Warmers (warm fuzzy birth stories, poems, etc.), and Just for Laughs (birth/baby/bf comics, amusing stories or sayings, etc.). We also brought the mom flowers, and said we hoped she would give birth before they were done blooming (she was fairly close to her date and ready to go... she did end up giving birth earlier, btw, so I would recommend the flowers over the hemp string idea!).
For another mom, we wrote simple affirmations/encouragements on a big poster-board, so she could read them (or have someone read them to her) during labor. The organizer also painted some wooden beads and had a poem or saying that went with each bead. We took turns pulling the beads out of a basket, reading the symbolism/meaning cards, and then strung them into a labor necklace for the mom.
We still have at least 3 more Mother Blessings coming up in the next month (including mine!), and another one the next month, so I'm excited to see what else the creative ladies in our group come up with!
Oh, btw, for Christain scriptures related to birth, this is a great resource.
http://www.ajoyfulbirth.com/Scripture