Even while a baby is in the womb, following baby’s growth is very important. Fetal growth is determined by measuring the length and weight of the fetus by ultrasound. Because of that, all pregnant women should be informed on how long and heavy their baby is at each ultrasound, except for the first examination when it is impossible to determine the baby’s measurements. However, the problem arises when pregnant women are not familiar with the average fetal weight and length for a given gestational period. In these situations, information about the fetal length and weight often confuses pregnant women and indicates worry whether their baby is growing as it should. To avoid such situations, our team of pediatricians has created The Fetal Growth Chart shown below. With our fetal growth chart, you can get information on the average fetal length and weight by gestational age.
How to determine fetal growth?
Baby’s life in the womb is divided into three developmental stages: germinal, embryonic and fetal. During this prenatal development, the baby grows very intensively. In nine months, a baby that is the size of a dot grows to a real baby with an average weight of about 3 kg or 6,8 lb.
During dating scan at around 8 weeks, doctors determine the fetal growth by measuring the fetus from its head to its bottom. This measure will be used to help determine the due date. From around 20 weeks of pregnancy, babies become more active, so the previous method becomes less accurate. Now doctors should check baby’s head circumference (HC), abdominal circumference (AC) and thigh bone (femur) length (FL). According to these measures, doctors determine fetal growth.
The Fetal Growth Chart below shows the exact measurements of the average fetal length and weight by gestational age. Also, you can download this fetal growth chart as an image. If you don’t know the length of your baby, but you know the length of his/her femur, you can find out that information using The Fetal Length Calculator.
The fetal growth chart from eight weeks to 19 weeks
| Pregnancy week | Length (cm) | Mass (g) | Length (inches) | Weight (ounces) |
|---|---|---|---|---|
| 8 weeks | 1.6 | 1 | 0.6 | 0.04 |
| 9 weeks | 2.3 | 2 | 0.9 | 0.07 |
| 10 weeks | 3.1 | 4 | 1.2 | 0.1 |
| 11 weeks | 4.1 | 7 | 1.6 | 0.2 |
| 12 weeks | 5.4 | 14 | 2.1 | 0.5 |
| 13 weeks | 7.4 | 23 | 2.9 | 0.8 |
| 14 weeks | 8.7 | 43 | 3.4 | 1.5 |
| 15 weeks | 10.1 | 70 | 4 | 2.5 |
| 16 weeks | 11.6 | 100 | 4.6 | 3.5 |
| 17 weeks | 13 | 140 | 5.1 | 4.9 |
| 18 weeks | 14.2 | 190 | 5.6 | 6.7 |
| 19 weeks | 15.3 | 240 | 6 | 8.5 |
The fetal growth chart from 20 weeks to 42 weeks
| Pregnancy week | Length (cm) | Mass (g) | Length (inches) | Weight (ounces) |
|---|---|---|---|---|
| 20 weeks | 25.6cm | 300g | 10in | 10.6oz |
| 21 weeks | 26.7cm | 360g | 10.5in | 12.7oz |
| 22 weeks | 27.8cm | 430g | 10.9in | 15.2oz |
| 23 weeks | 28.9cm | 500g | 11.4in | 1.1lb |
| 24 weeks | 30cm | 600g | 11.8in | 1.3lb |
| 25 weeks | 34.6cm | 660g | 13.6in | 1.5lb |
| 26 weeks | 35.6cm | 760g | 14in | 1.7lb |
| 27 weeks | 36.6cm | 875g | 14.4in | 1.9lb |
| 28 weeks | 37.6cm | 1kg | 14.8in | 2.2lb |
| 29 weeks | 38.6cm | 1.1kg | 15.2in | 2.5lb |
| 30 weeks | 39.9cm | 1.3kg | 15.7in | 2.9lb |
| 31 weeks | 41.1cm | 1.5kg | 16.2in | 3.3lb |
| 32 weeks | 42.4cm | 1.7kg | 16.7in | 3.7lb |
| 33 weeks | 43.7cm | 1.9kg | 17.2in | 4.2lb |
| 34 weeks | 45cm | 2.1kg | 17.7in | 4.7lb |
| 35 weeks | 46.2cm | 2.4kg | 18.2in | 5.3lb |
| 36 weeks | 47.4cm | 2.6kg | 18.7in | 5.7lb |
| 37 weeks | 48.6cm | 2.9kg | 19.1in | 6.3lb |
| 38 weeks | 49.8cm | 3.0kg | 19.6in | 6.8lb |
| 39 weeks | 50.7cm | 3.3kg | 20in | 7.2lb |
| 40 weeks | 51.2cm | 3.5kg | 20.2in | 7.6lb |
| 41 weeks | 51.5cm | 3.6kg | 20.3in | 7.9lb |
| 42 weeks | 51.7cm | 3.7kg | 20.3in | 8.1lb |
Of course, every baby is different, so don’t worry if the measurements in your maternity notes are different from The Fetal Growth Chart.
Some babies are simply smaller or bigger than others, just as some adults are skinny or obese. However, if your baby is bigger or smaller, it doesn’t mean that there will be something wrong with the baby when he/she is born. The practice proves that. Many babies born with weight less than 2 kg and more than 4 harmonized their growth with average baby very quickly.
Therefore, if your baby is deviating from the average fetal length and weight, but everything else is going the right way, you don’t need to worry. Just enjoy the beauty of pregnancy having in the mind that the mother’s spiritual peace is food for the mother and baby, while the pregnancy stress is their enemy.
*Bonus image for mothers who want to know and have a fetal / baby weight chart during pregnancy in grams / kg
*** Fetal weight percentile chart by week
Fetal weight chart in grams from 8 weeks to 27 weeks
Interesting facts: At 28 weeks of pregnancy, the fetus weighs about 1 kg!
Fetal weight chart in kg from 28 weeks to 42 weeks
Similarly, more pictures on Google search engine: fetal weight chart
