From this article in the London Times:
The birth certificates of children born from donated eggs and sperm would be marked with details of the way they were conceived, under proposals advanced yesterday [July 31, 2007] by MPs and peers.
A legal requirement to register such births openly is the only way of ensuring that children conceived from donors have the right to learn of their biological origins, a parliamentary committee that is scrutinising fertility reforms said. * * *
The suggestion raises significant privacy issues as birth certificates are public documents. Anybody would thus be able to find out whether any individual had been conceived from donated eggs or sperm.