What is the expected range for crown-rump length measurement in the first trimester?

The expected range for crown-rump length measurement during the first trimester is between 2 and 4 cm. This measurement is critical in early pregnancy as it helps assess gestational age and fetal growth. The crown-rump length is taken when the embryo is about 6 to 13 weeks old, and at this early stage, the fetus is relatively small, measuring within this range.

As the pregnancy progresses, fetal growth accelerates, leading to larger measurements; therefore, the other choices reflect measurements that would be more appropriate for later gestational weeks. Thus, understanding that the 2-4 cm range corresponds to early first-trimester development emphasizes its relevance for accurate dating and monitoring of embryonic growth.