Final answer:
The lower limit of gestational age for administering tocolytics is 24 weeks, as they are used to delay preterm labor and give the fetus more time to develop, increasing its chances of survival with each additional week.
Step-by-step explanation:
The lower limit of gestational age at which tocolytics should be given is 24 weeks. Tocolytics are medications used to delay preterm labor and their use is generally considered when premature birth is imminent. Gestational age is critical in this decision since the fetal viability and ability to survive outside the uterus improve significantly with each week of gestation. At 23 weeks, neonates have a 20-35% chance of survival, usually with extensive medical support. By 25 weeks, survival rates increase dramatically to as high as 70%, though still requiring intensive care. After 26 weeks, more than 90% of babies survive with essential medical care. Considering these statistics, tocolytics are typically administered no earlier than 24 weeks to balance the risks and benefits of early delivery and prolong pregnancy to allow for further fetal development, particularly of the respiratory system, reducing complications associated with prematurity.