An important thing to remember is that up until the past few decades, parents placing children were not given a choice about having an open or closed adoption - adoptions were closed, and there was no discussion about it. In the case of my original mom, although she voluntarily chose adoption for me, the hospital tried to deny her the chance to see me before she made the decision (thinking she wouldn't get attached if she didn't see me), but she refused to leave the hospital until she did, and she hoped every day from the day I was born until the day I found her that I would make contact again.
In many cases from the 1960s and earlier, women did not place their children voluntarily as my original mom did, but were coerced into placing their children for adoption - women who would have given birth and raised their children, but their parents, boyfriends, or others pressured them to sign away their parental rights.
Going forward, no person placing her child for adoption today should have any reasonable expectation that her child will never want to have contact, and the social workers need to make that clear.
Adoptee and Adoptive Mom.