Femur length
Abbreviation: FL
Femur length (FL) is the ultrasound measurement of your baby's thigh bone, the longest bone in the body. It is recorded from around 14 weeks onward and is one of four standard biometric measurements used to estimate fetal age and weight. FL helps confirm whether your baby's skeletal development is progressing normally for gestational age. Very short femur length relative to other measurements can sometimes prompt further assessment, though a wide range of normal values exists across different ethnicities. Your obstetrician will always interpret FL alongside other measurements rather than in isolation.
What This Means for You
Understanding Femur length is an important part of your second/third trimester journey. During pregnancy, your care team will use this term regularly. Being familiar with it means you can ask better questions and feel more confident at your antenatal appointments.
Explore our Pregnancy hubGood to Know
Singapore hospitals use ethnicity-adjusted growth charts, so an FL that looks low on a generic Western chart may be perfectly normal for a Southeast Asian baby. Always ask your doctor to explain results in the context of your specific chart.
Related Terms
Source: https://www.acog.org/womens-health/faqs/how-your-fetus-grows-during-pregnancy
Always consult your healthcare provider for personalised advice.
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