Fetal Growth Chart

the fetal average length and weight

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

fetal weight chart in grams

Interesting facts: At 28 weeks of pregnancy, the fetus weighs about 1 kg!

Fetal weight chart in kg from 28 weeks to 42 weeks

fetal weight chart in kg

Similarly, more pictures on Google search engine: fetal weight chart

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