Understanding Fetal Growth Percentiles
Fetal growth percentiles tell you how your baby's estimated weight compares to other babies at the same gestational age. This helps identify babies who may be growing too slowly (SGA) or too rapidly (LGA).
The INTERGROWTH-21st Project created international fetal growth standards, similar to how WHO standards work for postnatal growth. These standards account for both gestational age and sex.
| Classification | Percentile | What It Means |
|---|---|---|
| SGA (Small for Gestational Age) | < 10th | Baby is smaller than 90% of peers. May need closer monitoring. |
| AGA (Appropriate for Gestational Age) | 10th–90th | Normal range. Baby's growth is on track. |
| LGA (Large for Gestational Age) | > 90th | Baby is larger than 90% of peers. May indicate maternal diabetes or genetics. |
Typical Fetal Weights by Gestational Age
| Weeks | Median Weight | Weeks | Median Weight |
|---|---|---|---|
| 22 | ~450 g | 32 | ~2,150 g |
| 24 | ~650 g | 34 | ~2,670 g |
| 26 | ~910 g | 36 | ~3,210 g |
| 28 | ~1,250 g | 38 | ~3,710 g |
| 30 | ~1,670 g | 40 | ~4,120 g |
Track growth after birth
Continue monitoring with WHO standards after your baby arrives.