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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In this Article
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 |
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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Conclusion
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.
FAQs
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.
