These are very rare cases, adoption has been on the rise since 1979 and what did people do with their newborns when they didn't want them before abortion, give them up for adoption, c'mon my mom worked for an adoption agencies in 1980s, it peaked during that time
Sixties it was a rule to give up for adoptions haven't you heard of Little orphan Annie during 1950s
Adoption doesn't stop that girl from having to go through a potentially high-risk pregnancy because she's so young and then labor and delivery. No one should ever be forced to carry a child they either don't want or could kill them.
Also there are far more kids up for adoption than there are adoptive parents, contrary to what anti-choice propaganda would tell you. Do you know how many kids age out of foster care every day because nobody wanted them? The ones lucky enough to not be murdered or abandoned will end up in that wretched system. They don't get adopted for various reasons, mainly because everyone wants babies and children that don't have horrific pasts.
I used to work in a psych hospital and I saw the consequences of this every day. I will never forget a 22 year old I met who was abandoned at birth by his drugged-out teenage mother and was then raped and molested every day in foster care until he turned 18. Now he's constantly depressed, suicidal, on drugs, and in and out of the hospital because he can't function.