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Fetal Weight (kg) & Length (cm) During Pregnancy: Baby Development Chart by Week and Month


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Pregnancy is marked by the gradual growth and increasing size of the baby bump. You must have heard people saying, “Oh! My baby is the size of an orange now.” But does this indicate your developing fetus’s actual fetal weight and height?

Since the amniotic sac surrounds the baby, estimating the accurate length and weight by looking at the pregnancy bump won’t give accurate results. This is where the fetal weight and length chart comes into play.

This article will explore everything to know about the fetal weight and length chart during pregnancy and the significance surrounding the same.

Also Read: CRL in Ultrasound Scan Report During Pregnancy: Meaning, Full Form, What Does It Indicate and More

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What is the Fetal Weight chart?

The fetal weight chart gives an average idea about the corresponding weight of the growing fetus with each week in the pregnancy. The fetal weight chart gives an average figure, and the actual weight of the fetus will most significantly vary from one pregnancy to the other.

However, any drastic difference from the average can signify an anomaly in the growth of the fetus in the womb. These situations call for further testing and medical intervention.

Following is the medically accepted fetal weight chart used for reference during pregnancy:

Pregnancy Week Average Weight
8 weeks 1g
9 weeks 2g
10 weeks 4g
11 weeks 7g
12 weeks 14g
13 weeks 23g
14 weeks 43g
15 weeks 70g
16 weeks 100g
17 weeks 140g
18 weeks 190g
19 weeks 240g
20 weeks 300g
21 weeks 360g
22 weeks 430g
23 weeks 501g
24 weeks 600g
25 weeks 660g
26 weeks 760g
27 weeks 875g
28 weeks 1kg
29 weeks 1.2kg
30 weeks 1.3kg
31 weeks 1.5kg
32 weeks 1.7kg
33 weeks 1.9kg
34 weeks 2.1kg
35 weeks 2.4kg
36 weeks 2.6kg
37 weeks 2.9kg
38 weeks 3.1kg
39 weeks 3.3kg
40 weeks 3.5kg


Also Read: Quadruple Marker Test in Pregnancy: What is It, Normal and Abnormal Test Results, Cost in India

What is the Fetal Length chart?

Keeping track of the fetal length during the pregnancy is just as important as the fetal weight. The ultrasound technicians measure the fetal length from the crown of the head to the bottom. This length is measured because most of the fetus stays curled inside the womb. This makes it difficult to measure the exact length of the baby from head to toe.

From the 20th week onwards, the fetal length is measured from the crown to the heel of the baby’s anatomy.

Also Read: Internal OS Closed: What Does It Mean in Pregnancy Scan Report

Pregnancy Week Average Length
8 weeks 1.6cm
9 weeks 2.3cm
10 weeks 3.1cm
11 weeks 4.1cm
12 weeks 5.4cm
13 weeks 7.4cm
14 weeks 8.7cm
15 weeks 10.1cm
16 weeks 11.6cm
17 weeks 13cm
18 weeks 14.2cm
19 weeks 15.3cm
20 weeks 25.6cm
21 weeks 26.7cm
22 weeks 27.8cm
23 weeks 28.9cm
24 weeks 30cm
25 weeks 34.6cm
26 weeks 35.6cm
27 weeks 36.6cm
28 weeks 37.6cm
29 weeks 38.6cm
30 weeks 39.9cm
31 weeks 41.1cm
32 weeks 42.4cm
33 weeks 43.7cm
34 weeks 45cm
35 weeks 46.2cm
36 weeks 47.4cm
37 weeks 48.6cm
38 weeks 49.8cm
39 weeks 50.7cm
40 weeks 51.2cm


Also Read: Is Vaginal Birth Safe After Cesarean Delivery? New Research Says there is Over 20% Increased Chances of Perineal Tear

How often does the doctor measure the Fetal weight and length?

The accurate checking and reading of the fetal weight and length are recorded during four ultrasound scans during pregnancy. They include:

Dating and viability scan

This is done between six to nine weeks of gestation. During this scan, the fetus’s crown to rump length (CRL) gives a tentative idea of the baby’s due date.

Nuchal translucency area

This is done between 11-13 weeks of gestation. This is a crucial ultrasound scan and assesses if the baby has Down’s syndrome.

Anomaly scan or mid-pregnancy scan

This is done between 18-20 weeks of gestation. During this scan, the doctor not just prioritizes the overall fetal weight and length but other prospects too. These include the head circumference, abdominal circumference, femur length.

Growth scan

This is done between 28-32 weeks of gestation to check the fetal well-being and ensure that the baby’s growth is right.

What Is the Significance of Fundal Height in Baby’s Growth and Development?

The fundal height is the height measurement from the tip of the womb from the abdomen. The fundal height is generally equal to the number of weeks of the pregnancy (plus or minus 2 cm).

The growth of the fundal height increases as the pregnancy progresses.

  • During the 12th week, the womb reaches around the upper edge of the pubic bone.
  • During the 22nd week, the womb reaches just beneath the belly button.
  • During the 24th week, the womb reaches just above the belly button.
  • During the 36th week, the fundal height is typically at its maximum and the womb is just beneath the sternum.

In case of any drastic differences in the fundal height compared to the average, the doctor will instruct undergoing further scans for a better diagnosis of an underlying anomaly.

Common Terminologies Associated with Fetal Growth

When assessing fetal growth and length, several markers are involved. A healthy fetus measures between the 10th and 90th percentile.

Common terms associated with fetal growth include:

Common terminologies Definition
Crown-Rump Length Gives an estimate of the fetus’s average length. Estimates the due date of the baby too.
Biparietal Diameter Measures the transverse width of the fetus’ head in the widest part.
Femur and Humerus Length Measures the length of the largest bones in the hands and limbs to check for skeletal dysplasia.
Abdominal Circumference Measures and assesses fetal growth and the optimal growth proportions. Measured during the second half of the pregnancy.
Gestational Sac Measures the number of weeks of the pregnancy.
Foetal Pole Dates an early pregnancy.


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The fetal growth chart, including the weight and length, is an important marker of the fetus’ growth and development. It indicates the healthy progress of the pregnancy. Any apparent anomaly during these scans indicates if further medical intervention or testing is necessary. This is one of the primary reasons why getting timely scans is a prerequisite for a healthy pregnancy.


What is normal fetal weight at 34 weeks in kg?

The normal fetal weight at 34 weeks is around 2.1 kg and the fetus should measure around 30 cm by that week. However, remember that every baby has subjective growth and development, so the numbers might vary.

What is the ideal fetal weight during 36 weeks of pregnancy?

By week 36, the fetal weight in kg should be 2.6 kg. The baby should also measure 47.4 cm from their head to their heel.

Are 36 weeks OK for delivery?

By 36 weeks, which is the ninth month of pregnancy, the baby is healthy and developed to be delivered naturally without involving any complications. It is a subjective situation because every pregnancy is different.

Somapika Dutta (B.Sc Physiology, Honours)
Somapikar holds Bachelors Degree in Physiology from University of Culcutta. She has 6+ years of experience writing in different niches, including health, tech and lifestyle. An animal enthusiast and a raging foodie, experiencing life - one day at a time.


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