Betamethasone is used to stimulate fetal lung maturity and surfactant production in fetuses between which weeks?

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

Answer: (A)

Betamethasone is given to speed up fetal lung maturation when preterm birth is likely, so the fetus has time to develop sufficient surfactant to keep the airways open after birth. It works by accelerating the maturation of type II pneumocytes and increasing production of lung surfactant, which lowers surface tension and helps prevent atelectasis in the immature lungs.

The most beneficial window is between about 24 and 34 weeks of gestation. Before 24 weeks, fetal lungs are too immature to gain meaningful benefit, and after 34 weeks the risk of respiratory distress syndrome is already markedly reduced because surfactant production is usually adequate. Administering the steroid during 24–34 weeks optimizes the chance of preventing RDS and related complications in the preterm newborn.