Answer:
To provide a baseline for judging the survival rates of infants who received whole-body cooling
Step-by-step explanation:
In this case, the purpose of the experiment is to see whether reducing body temperature for three days after birth increased the rate of survival without brain damage.
Then, the proposed method (whole-body cooling) has to be contrasted with the baseline, in this case, the "usual care". If we want to know if this proposed method is statistically better, we have to compare with these baseline with random sampling out of the same population.
If it is not compared to nothing or to a new method, it wouldn't be possible to conclude if the method is better or not than the usual care.