WHO Fetal Growth Charts, 2017

When

The World Health Organization fetal growth charts were published in 2017 in PLOS Medicine.

Who Developed It

The charts were produced by an international research team working with the World Health Organization. The published article lists Torvid Kiserud, Gilda Piaggio, Guillermo Carroli, Mariana Widmer, José Carvalho, Lisa Neerup Jensen, Daniel Giordano, José Guilherme Cecatti, Hany Abdel Aleem, Sameera A. Talegawkar, and additional collaborators.

The work was funded by the UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, Department of Reproductive Health and Research, World Health Organization.

Source: https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002220

Why This Source Is Credible

This source is credible because it was published in a peer-reviewed medical journal, was produced with World Health Organization involvement, and used a prospective multinational study design. The publication describes the study population, pregnancy risk criteria, gestational-age confirmation method, ultrasound schedule, and statistical approach.

The study was designed to create fetal growth references from low-risk singleton pregnancies rather than from a mixed clinical population with unknown risk factors.

Who Was Included

The study followed low-risk singleton pregnancies from 10 countries:

• Argentina
• Brazil
• Democratic Republic of the Congo
• Denmark
• Egypt
• France
• Germany
• India
• Norway
• Thailand

Participants were women of high or middle socioeconomic status without known environmental constraints on fetal growth. Gestational age was checked using crown-rump length measured at 8 to 13 weeks. The final study population included 1,387 participants.

Measurement Type

This source is based on ultrasound estimated fetal weight and fetal biometric measurements, not direct fetal weighing. Estimated fetal weight is calculated before birth from ultrasound measurements, so values can vary with measurement quality, fetal position, equipment, and the formula used.

How It Was Built

This was a multinational prospective longitudinal ultrasound study. Participants had scheduled assessments during pregnancy, including repeated ultrasound examinations. The researchers collected common fetal biometric measurements and used them to produce fetal growth charts, including estimated fetal weight.

Estimated fetal weight is not directly weighed before birth. It is calculated from ultrasound measurements, commonly including head, abdomen, and femur measurements. The WHO paper reports percentile charts for estimated fetal weight and several ultrasound biometric measurements.

What It Means

The WHO chart shows how an estimated fetal weight compares with values from a multinational low-risk singleton pregnancy reference group.

For example, a 50th percentile value means that the estimate is near the middle of the reference distribution for that gestational age. A lower or higher percentile means the estimate is lower or higher relative to this reference group, not automatically abnormal.

How To Interpret It

Use the WHO chart as a broad international comparison point. It can be especially helpful when no high-quality local reference is available.

The chart should be interpreted as a reference position, not a clinical conclusion. A percentile result needs context: gestational dating accuracy, ultrasound measurement quality, interval growth, maternal and fetal history, and the clinician's assessment all matter.

What This Source Should Not Be Used For

This source should not be used by itself to diagnose fetal growth restriction, macrosomia, placental insufficiency, or pregnancy risk. It provides a reference comparison only. Clinical interpretation requires medical history, ultrasound quality, gestational dating, growth trend, and clinician assessment.

Limitations

• The study included 10 countries, but it still represents only a limited selection of global populations.
• The authors reported significant differences in estimated fetal weight growth between countries.
• Maternal age, height, weight, parity, and fetal sex influenced estimated fetal weight to some degree.
• Estimated fetal weight is calculated from ultrasound measurements and is therefore subject to measurement and formula error.
• The WHO paper itself notes that local testing, adjustment, customization, or replacement may be needed in some clinical settings.

Bottom Line

The WHO fetal growth chart is a strong international reference built from a prospective, multinational, low-risk pregnancy cohort. Its main value is broad comparability. Its main limitation is that an international average reference may not fit every local population or every individual pregnancy.