In another study that compared mothers who released their children to those who raised them, mothers who released their children were more likely to delay their next pregnancy, to delay marriage, and to complete job training. However, both groups reached lower levels of education than their peers who were never pregnant.[124] Another study found similar consequences for choosing to release a child for adoption. Adolescent mothers who released their children were more likely to reach a higher level of education and to be employed than those who kept their children. They also waited longer before having their next child.[122] Most of the research that exists on adoption effects on the birth parents was conducted with samples of adolescents, or with women who were adolescents when carrying their babies—little data exists for birth parents from other populations. Furthermore, there is a lack of longitudinal data that may elucidate long-term social and psychological consequences for birth parents who choose to place their children for adoption.
In the 1970s, as adoption search and support organizations developed, there were challenges to the language in common use at the time. As books like Adoption Triangle by Sorosky, Pannor and Baran were published, and support groups formed like CUB (Concerned United Birthparents), a major shift from "natural parent" to "birthparent"[182][183] occurred. Along with the change in times and social attitudes came additional examination of the language used in adoption.
Unlike guardianship or other systems designed for the care of the young, adoption is intended to effect a permanent change in status and as such requires societal recognition, either through legal or religious sanction. Historically, some societies have enacted specific laws governing adoption; where others have tried to achieve adoption through less formal means, notably via contracts that specified inheritance rights and parental responsibilities without an accompanying transfer of filiation. Modern systems of adoption, arising in the 20th century, tend to be governed by comprehensive statutes and regulations.
The period 1945 to 1974, the baby scoop era, saw rapid growth and acceptance of adoption as a means to build a family.[40] Illegitimate births rose three-fold after World War II, as sexual mores changed. Simultaneously, the scientific community began to stress the dominance of nurture over genetics, chipping away at eugenic stigmas.[41][42] In this environment, adoption became the obvious solution for both unwed people and infertile couples.[43]

Private domestic adoptions: under this arrangement, charities and for-profit organizations act as intermediaries, bringing together prospective adoptive parents and families who want to place a child, all parties being residents of the same country. Alternatively, prospective adoptive parents sometimes avoid intermediaries and connect with women directly, often with a written contract; this is not permitted in some jurisdictions. Private domestic adoption accounts for a significant portion of all adoptions; in the United States, for example, nearly 45% of adoptions are estimated to have been arranged privately.[83]
Open records: Movements to unseal adoption records for adopted citizens proliferated along with increased acceptance of illegitimacy. In the United States, Jean Paton founded Orphan Voyage in 1954, and Florence Fisher founded the Adoptees' Liberty Movement Association (ALMA) in 1971, calling sealed records "an affront to human dignity.".[158] While in 1975, Emma May Vilardi created the first mutual-consent registry, the International Soundex Reunion Registry (ISRR), allowing those separated by adoption to locate one another.[159] and Lee Campbell and other birthmothers established CUB (Concerned United Birthparents). Similar ideas were taking hold globally with grass-roots organizations like Parent Finders in Canada and Jigsaw in Australia. In 1975, England and Wales opened records on moral grounds.[160]
His solution was outlined in The Best Method of Disposing of Our Pauper and Vagrant Children (1859) which started the Orphan Train movement. The orphan trains eventually shipped an estimated 200,000 children from the urban centers of the East to the nation's rural regions.[28] The children were generally indentured, rather than adopted, to families who took them in.[29] As in times past, some children were raised as members of the family while others were used as farm laborers and household servants.[30] The sheer size of the displacement—the largest migration of children in history—and the degree of exploitation that occurred, gave rise to new agencies and a series of laws that promoted adoption arrangements rather than indenture. The hallmark of the period is Minnesota's adoption law of 1917 which mandated investigation of all placements and limited record access to those involved in the adoption.[31][32]