When my sister-in-law and brother were expecting their first child I wrote a short prayer for them and printed it on blue cardstock (since they were having a boy.) I purchased a pack of blue votive candles and glass holders and wrapped them in tulle. The prayer was attached to the candle with yellow ribbon and a cute diaper pin. (You can also use tea candles if you want to cut the cost.)
The candles can be given to the guests as a parting gift. When the mom-to-be goes into labor have someone call, email, or text the others to light their votive candle and say a prayer.
You can use the following prayer (fill in your own names) or another prayer, a poem, scripture verse, etc instead.

Prayer for the Votive Candles
Heavenly Father, We place (MOM’S NAME) & (DAD’S NAME) into your hands as they prepare for the birth of their child (BABY’S NAME IF KNOWN). Give (MOM) strength of body, mind and spirit. Calm her fears and bring peace to her heart. Protect her and (BABY) from all harm and may they have a safe and healthy delivery. St. Joseph, protector of the family, give (DAD) strength, courage and compassion as he helps (MOM) during labor. Mother Mary, watch over (DAD), (MOM) & little (BABY) today & always. May they grow in their love for God & forever be a shining light of Christ in the world. Amen
Do you have another idea to share? Email me at rol@revolutionoflove.com. Thanks!