Final answer:
Corticosteroids are injected into pregnant women at risk for preterm labor to improve the premature baby's chances of survival by aiding lung development.
Step-by-step explanation:
Injecting pregnant women at risk for delivering premature babies with corticosteroids increases the babies' chances of survival. Corticosteroids work by enhancing the development of the fetus's lungs, thereby helping to reduce the risk of respiratory difficulties, a common problem with premature births. The use of corticosteroids has been a standard practice to increase neonatal survival rates in premature deliveries. Unlike other options listed, corticosteroids specifically address the development issues related to premature birth, while options like gamma globulin and tetracycline are not typically used in this context and saline solution is not a medication.