Question

Gestational age can be estimated by ultrasound measurement of maternal abdominal circumference, fetal femur length, and fetal head size. when are these most accurate?

Answer 1

The most accurate ultrasound measurements for estimating gestational age occur during the second trimester, particularly between weeks 18 to 22.

Step-by-step explanation:

Ultrasound imaging is the technique of choice for studying fetal growth and development due to its safety, non-invasiveness, and accuracy. Estimates of gestational age based on ultrasound measurements such as maternal abdominal circumference, fetal femur length, and fetal head size are most accurate during the second trimester, particularly between weeks 18 to 22. Beyond this period, fetal growth can vary due to numerous biological factors; however, ultrasound remains a vital tool for monitoring the fetus, with the ability to identify conditions such as intrauterine growth restriction (IUGR) and assess the viability of the fetus. The growth of the fetus is typically linear until the final weeks before birth when the fetus rapidly gains body fat and weight.