The demand for adoption of infants has also fallen off a cliff due to the availabilty amd now NHS funding of IVF and other assisted conception techniques.
That is not an argument against NHS funding btw, just a statement of reality.
It is now easier and quicker even with (successful) IVF to have a birth child than be approved for infant adoption.
Adopters as a result have become (again, in no way a criticism) choosier about what children they will accept. Children at risk from foetal alcohol syndrome, children of mixed or non white heritage, children exposed to drug use during pregnancy, these are all infants who already struggle to find any adoptive placement.
People are rightly encouraged to be honest and say if they would find it difficult to accept an adoption child rather than their “own” child and are screened out as a result. Again, not a criticism. I know a number of couples with fertility difficulties who absolutely ruled out adoption on this basis.
This is not the 1960s. There are not desperate willing adopters for thousands of unwanted babies with poor prenatal circumstances.