Nuchal translucency is measured at approximately which gestational age?

• A. 9 weeks
• B. 12 weeks + 6 days
• C. 14 weeks
• D. 11 weeks

Answer: (B)

Nuchal translucency is measured in the first trimester when the fetus is in a suitable window for reliable assessment of the fluid behind the neck. The typical or optimal window is roughly between 11 and 13 6/7 weeks of gestation, with many clinicians aiming near 12 weeks to 13 weeks. The exact timing around 12 weeks plus a few days (about 12 weeks 6 days) sits in the middle of this window and provides the most accurate measurement that will be used alongside crown-rump length and maternal serum markers to estimate aneuploidy risk. Measuring this too early (around 9 weeks) can be technically challenging because the structure is small and less defined, while measuring closer to 14 weeks reduces the usefulness of NT for first-trimester screening.