It is not about 1968 but the science of 1968. In 1968, we had very little ability to help a premature baby. Most babies born before 34 weeks died. I could not find any exact numbers for survival rates of premature babies from 1968, but I think you will agree that a baby born at 24 weeks in 1968 had NO chance of survival.
Contrast that with this statement
"However, according to this
2016 analysis of more than 8,300 deliveries in the United States, babies born
at 24 weeks had a 68 percent chance of survival. A
2016 cohort study of more than 6,000 births found a survival rate of 60 percent"
source -
https://www.healthline.com/health/baby/premature-baby-survival-rate#24-weeks
Knowing what we know now, the 'viability' of an unborn baby went from 34 weeks in 1968 to around 24 weeks in 2016. To allow 1968 science to drive 2021 decisions is irrational. Who knows what it will be 2068?