Other studies provide evidence that adoptive relationships can form along other lines. A study evaluating the level of parental investment indicates strength in adoptive families, suggesting that parents who adopt invest more time in their children than other parents and concludes, "...adoptive parents enrich their children's lives to compensate for the lack of biological ties and the extra challenges of adoption." Another recent study found that adoptive families invested more heavily in their adopted children, for example, by providing further education and financial support. Noting that adoptees seemed to be more likely to experience problems such as drug addiction, the study speculated that adoptive parents might invest more in adoptees not because they favor them, but because they are more likely than genetic children to need the help.
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" occurred. Along with the change in times and social attitudes came additional examination of the language used in adoption.
Foster care adoption: this is a type of domestic adoption where a child is initially placed in public care. Many times the foster parents take on the adoption when the children become legally free. Its importance as an avenue for adoption varies by country. Of the 127,500 adoptions in the U.S. in 2000 about 51,000 or 40% were through the foster care system.
Adoption practices have changed significantly over the course of the 20th century, with each new movement labeled, in some way, as reform. Beginning in the 1970s, efforts to improve adoption became associated with opening records and encouraging family preservation. These ideas arose from suggestions that the secrecy inherent in modern adoption may influence the process of forming an identity, create confusion regarding genealogy, and provide little in the way of medical history.
During the same period, the Progressive movement swept the United States with a critical goal of ending the prevailing orphanage system. The culmination of such efforts came with the First White House Conference on the Care of Dependent Children called by President Theodore Roosevelt in 1909, where it was declared that the nuclear family represented "the highest and finest product of civilization" and was best able to serve as primary caretaker for the abandoned and orphaned. Anti-institutional forces gathered momentum. As late as 1923, only two percent of children without parental care were in adoptive homes, with the balance in foster arrangements and orphanages. Less than forty years later, nearly one-third were in an adoptive home.
The practice of closed adoption (aka confidential or secret adoption), which has not been the norm for most of modern history, seals all identifying information, maintaining it as secret and preventing disclosure of the adoptive parents', biological kins', and adoptees' identities. Nevertheless, closed adoption may allow the transmittal of non-identifying information such as medical history and religious and ethnic background. Today, as a result of safe haven laws passed by some U.S. states, secret adoption is seeing renewed influence. In so-called "safe-haven" states, infants can be left, anonymously, at hospitals, fire departments, or police stations within a few days of birth, a practice criticized by some adoption advocacy organizations as being retrograde and dangerous.
The number of adoptions in the United States peaked in 1970. It is uncertain what caused the subsequent decline. Likely contributing factors in the 1960s and 1970s include a decline in the fertility rate, associated with the introduction of the pill, the completion of legalization of artificial birth control methods, the introduction of federal funding to make family planning services available to the young and low income, and the legalization of abortion. In addition, the years of the late 1960s and early 1970s saw a dramatic change in society's view of illegitimacy and in the legal rights of those born outside of wedlock. In response, family preservation efforts grew so that few children born out of wedlock today are adopted. Ironically, adoption is far more visible and discussed in society today, yet it is less common.
Psychologists' findings regarding the importance of early mother-infant bonding created some concern about whether parents who adopt older infants or toddlers after birth have missed some crucial period for the child's development. However, research on The Mental and Social Life of Babies suggested that the "parent-infant system," rather than a bond between biologically related individuals, is an evolved fit between innate behavior patterns of all human infants and equally evolved responses of human adults to those infant behaviors. Thus nature "ensures some initial flexibility with respect to the particular adults who take on the parental role."