What does "hl" mean in prenatal checkups?

Fetal HL usually refers to the humeral length of the fetus. This examination is typically performed during the second trimester using ultrasound imaging and serves as one of the important indicators for assessing fetal growth and development in utero.

The fetal humeral length refers to the length of the upper arm bone (not the femur, as incorrectly stated in the original text). After 12 weeks of gestation, the embryo has developed into a fetus. Pregnant women usually undergo ultrasound examinations, through which the humeral length can be measured and evaluated as a reference index for fetal growth and health status. At different stages of pregnancy, the fetal humeral length falls within specific standard ranges. If the measurement is 5% or more below the expected value, further medical evaluation may be recommended to rule out potential developmental abnormalities.

When an ultrasound during the second or third trimester reveals a shorter-than-normal fetal humeral length, it may be closely associated with certain genetic disorders such as dwarfism, Edwards syndrome, Down syndrome, and other related conditions. If such congenital abnormalities are suspected, additional diagnostic tests—such as 4D color Doppler ultrasound, amniocentesis, or genetic testing—may be required.