भ्रूण की लंबाई का परसेंटाइल (CRL और CHL)

What is the difference between CRL and CHL?

**CRL (crown–rump length)** measures from the top of the head to the bottom of the torso and is used mainly in **early pregnancy**. **CHL (crown–heel length)** estimates full body length and is used later when limbs are visible.

Which weeks can I use this tool for?

In **CRL mode**, you can choose weeks **6–14**. In **CHL mode**, you can choose **14–42**. If you switch modes, the week is automatically kept within the valid range.

What does “Within typical range” actually mean?

It means your length lies between the approximate **10th and 90th percentiles** for that week in this model. Many babies are there, but some healthy babies will be below or above.

Does a “Below typical” or “Above typical” result mean something is wrong?

Not by itself. It only says your measurement is outside the 10th–90th band in this model. Your provider will look at patterns over time, Dopplers, fluid and other findings before deciding anything.

Can I use values from different scans?

You should match **week and length from the same scan**. Do not mix a week from one appointment with a length from another, or it will distort the percentile.

Does this replace the growth charts in my hospital?

No. Hospitals may use their own reference charts and rules. This is an **educational tool** only and cannot replace local standards or medical judgement.