What is puthra kaamesti yagam?

What is puthra kaamesti yagam? For what type of dosham is this yagam done? Is this related to previous birth?
Update: Is this yagna simple to perform.. Will there be priests who can do this? If this is not related to any dosha, then why was asked to perform this?Do someone need to follow tough rules and regulations while perform this yagna?Which are the specific places where we can do this? Sorry for too many questions. Thanks
8 answers