Putting a child up for adoption is a huge undertaking. It requires the mother to carry the child in her womb for nine months, during which time a bond is created with the child. As a result, many mothers who have given a child up for adoption often suffer intense feelings of loss which last for the rest of their lives.
Many women would prefer to abort the foetus than being forced into completing the full term the pregnancy. Partly, this is because although there is a large number of families hoping to adopt an infant, children from ethnic minorities often languish in foster homes and grow up in social services. Adoptive parents do not adopt babies of colour at the same rates they do young, white children.
If a pregnant woman chooses to go through the pregnancy and relinquish her child, that is a noble and selfless decision. But that is her decision to make. Adoption is always an option, but it should never be the ONLY option and it is certainly not her duty.