Another option for unwed mothers was the sometimes unpleasant Mother and Babies Homes. Here are a couple links to websites about the homes. Quite a few unwed mothers have thier children taken from them after giving birth in these institutions, and is is extremely diffuclt if not impossible to find records of the births.
http://www.motherandbabyhomes.com/http://www.pbs.org/opb/historydetectives/investigation/unwed...http://www.theguardian.com/lifeandstyle/2007/oct/31/familyan...