Betamethasone is given to promote fetal lung maturity for fetuses between which gestational ages?

• A. 24-34 weeks
• B. 28-40 weeks
• C. 12-20 weeks
• D. 34-36 weeks

Answer: (A)

Anticipating preterm birth, betamethasone is given to accelerate fetal lung maturity. It works by stimulating the fetus’s type II pneumocytes to produce surfactant, speeding up lung development and improving the lecithin-to-sphingomyelin ratio. This helps reduce the risk of neonatal respiratory distress syndrome after birth. The window for giving this steroid is roughly 24 to 34 weeks of gestation, because within this range the benefit is greatest: earlier than 24 weeks the lungs are too immature to gain much protection, and after 34 weeks lung maturity is typically sufficient and the added benefit, along with potential risks, is less clear. The treatment is typically given when preterm delivery is likely within the next week, often as two intramuscular doses 24 hours apart.