So what do the volunteers do? According to Spence-Chapin's website, volunteer families care for the newborn for a period of days or several weeks. They take the babies to all doctor appointments, take the baby to visitations with either the birth or adoptive parents and document any milestones with photos and written observations.
One woman, whose youngest son died in a 2009 skiing accident, has cared for 20 babies since 2010.
"My job is to make the baby feel safe and love 24-7," Susan Singer told ABC News.
"I hold them all the time. I talk to them. I sing to them. We play music. And I get so much joy and pleasure. I feel so good when I'm with an infant that I hope that it does ... something for them, too," Singer added.
The only cost to the volunteers is their love for the children. The adoption agency pays for the expenses including diapers, car seats and doctor visits, ABC News reported.
There are 159,000 children either adopted or waiting to be adopted in the U.S. in 2014, according to data compiled by the Department of Health and Human Services.