Preterm birth is defined as birth occurring after how many weeks of gestation?

• A. Under 20 weeks
• B. 38-42 weeks
• C. Over 20 weeks
• D. 28-32 weeks

Answer: (C)

The key idea here is gestational age thresholds used to classify pregnancy outcomes. Birth is generally considered a live birth once the pregnancy has progressed beyond a viability threshold, commonly around 20 weeks. That means births occurring after 20 weeks are counted as a birth event, while pregnancies ending before that are typically labeled miscarriages. Preterm birth, specifically, refers to birth before full term (before 37 weeks), but the choice framed as “after how many weeks” points to the threshold where a birth is recognized rather than a fetal loss. Therefore, “over 20 weeks” is the best fit. The other options don’t match: under 20 weeks is usually miscarriage, 38–42 weeks is term, and 28–32 weeks is just a subset of preterm, not the threshold.