Searching absolutely can disrupt the birhtmother's life (likewise, birthparents searching can equally disrupted the adoptees lives). That doesn't mean it always will, but I think if anybody (birthparent, birth sibling, or adoptee) wants to conduct a search, they must do so responsibily and take into consideration a number of factors:
- the adoptee/birth relative may not want to be found
- the adoptee may not have been told he or she was adopted (this is increasingly rare in recent adoptions, but this has not always been the case)
- the birthparent may not have disclosed to his or her family that they had a child previously
- the birthparent may be in active denial about her grief over the adoption
When you are searching for a birth relative, you don't know what that persons's life situation is. You don't always know what their feelings are about the adoption -- anger, denial, and grief are often all bound together, they are all part of the grieving process so it's not unusual that the person may be in any of these stages of grief.
In my birthmother's case, she had not told any of her current family members about me. She had been in active denial over my adoption. She did not even think of me for many many years because the grief was too hard for her to process. She'd also isolated herself from anybody who could have helped her through the grieving process because she never told anybody about me.
I was fortunate that I met her at a time she had actually been thinking about me and wanted to know how I was doing, but if I had found her even just a year or two earlier, it would have been a completely different situation.
My birthfather on the other hand, told his wife before he married her that he'd had a daughter out of wedlock. It was his wife in fact who prepared him for the fact that I would probably come looking for him one day.