Protocol - Fetal Growth Assessment - Percentiles for U.S. Populations

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Fetal Growth Standards Based on the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies


Publicly available


Determination of fetal growth is a three-step process:

Step 1: Ascertainment of estimated fetal weight (EFW)

Step 2: Verification of gestational age (GA) at which the EFW was recorded

Step 3: Determination of EFW or biometry percentiles by plotting the EFW or relevant biometric measures at the appropriate GA on a pre-defined fetal growth curve


1. Ascertainment of Estimated Fetal Weight (EFW)

The investigator is encouraged to utilize one of the following approaches for documentation of EFW. Approach (a) is the preferred approach for retrospective studies, although it is recognized that biometric data may be less easily accessible in retrospective investigations, and as such approach (b) is provided as an alternative.

(a) EFW (preferably in grams) derived by review of available ultrasound reports to obtain relevant biometric measures (bi-parietal diameter [BPD], head circumference [HC], abdominal circumference [AC], and femur length [FL]), followed by calculation of EFW from formula provided by Hadlock (see Hadlock et al., 1985).

    Date of ultrasound: ____________________ (DD/MMM/YYYY)

    Gestational Age: ________ weeks ________ days (as per protocol for GA)

    Biometric measures as they appear on the ultrasound report:

    Bi-parietal diameter (BPD): __________ mm

    Head circumference (HC): ___________ mm

    Abdominal circumference (AC): ___________ mm

    Femur length (FL): ___________ mm

    Estimated Fetal Weight (EFW): ________________ grams

(b) EFW (preferably in grams) abstracted from ultrasound report contained within the medical record:

    Date of ultrasound: ____________________ (DD/MMM/YYYY)

    Gestational Age: ________ weeks ________ days (as per protocol for GA)

    Estimated Fetal Weight: ________________ grams

2. Verification of Gestational Age (GA)

The PhenX measure for Gestational Age - Medical Record Abstraction is considered essential for interpretation of this measure.

3. Plotting the EFW or Biometric Measures - US populations

Determination of fetal growth should then be undertaken, by plotting EFW or biometric measures on a growth curve, allowing for determination of percentiles, by using the following protocol:

    NICHD Fetal Growth Studies

*An SR of 11 methods of EFW assessment did not identify a superior formula; given that Hadlock (1985) is the most widely used formula, it may provide the greatest degree of consistency across studies

Once biometric measures and gestational age have been obtained using one of the approaches described, the investigator should consult the Fetal Growth Standard established via the NICHD Fetal Growth Studies, to determine the specific, ethnicity-specific, EFW percentile. See Table 2 in the Buck Louis et al. 2015 publication for the EFW percentiles of the different ethnicities.

Personnel and Training Required

Personnel who are trained in performing medical records review.

Equipment Needs



Requirement CategoryRequired
Average time of greater than 15 minutes in an unaffected individualNo
Major equipmentNo
Specialized requirements for biospecimen collectionNo
Specialized trainingNo

Mode of Administration


Life Stage:

Adolescent, Adult, Pregnancy

Specific Instructions:

Utilization of Fetal Growth Standards based on the Fetal Growth Longitudinal Study (FGLS) is recommended. Another protocol used in international settings, the INTERGROWTH 21st Fetal Growth Standards, is available in Supplemental Information.

Research Domain Information

Release Date:

April 11, 2017


This measure includes abstraction of fetal growth and ultrasound information from a medical record.


Fetal growth is a gestational age-dependent measure of fetal size, measured in grams, in relation to a defined standard growth curve. Fetal growth at both extremes of pathology (Small for gestational age [SGA] and large for gestational age [LGA]) affects fetal/neonatal outcome and has been linked with a variety of comorbidities encountered in later life.

Selection Rationale

This is a robust methodology, accounting for ethnic differences in fetal growth in the United States. The protocol is accessible and easy to use. The formula chosen to calculate estimated fetal weight (EFW), which was then used to develop the fetal growth percentiles, is well-known and widely-available. Researchers searching for a protocol for fetal growth assessment can apply this formula with ease to calculate the EFW for their study, using biometry measures as described above, to be plotted on the available Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) growth curves.

This measure was derived from prospective follow-up of healthy women with low-risk, singleton pregnancies from 12 community and perinatal centers in the United States, including non-Hispanic whites, non-Hispanic blacks, Hispanics, and Asians. Women were screened from 8+0 to 13+6 weeks gestational age (GA) for maternal health status associated with presumably normal fetal growth (aged 18-40 years, body mass index [BMI] 19.0-29.9 kg/m2, healthy lifestyles and living conditions, low-risk medical and obstetrical history). The fetuses of 74% of women continued to be low risk (uncomplicated pregnancy, absent anomalies) at birth, and their measurements were included in the standards.




Common Data Elements (CDE)Fetus Growth Curve Percentile Percentile Rank Value5747180CDE Browser

Process and Review

The Expert Review Panel has not reviewed this measure yet.


Buck Louis, G. M., Grewal, J., Albert, P. S., Sciscione, A., Wing, D. A., Grobman, W. A., Newman, R. B., Wapner, R., D’Alton, M. E., Skupski, D., Nageotte, M. P., Ranzini, A. C., Owen, J., Chien, E. K., Craigo, S., Hediger, M. L., Kim, S., Zhang, C., & Grantz, K. L. (2015). Racial/ethnic standards for fetal growth: the NICHD Fetal Growth Studies. American Journal of Obstetrics & Gynecology, 213(4), 449.e441-449.e441.

Hadlock, F. P., Harrist, R. B., Sharman, R. S., Deter, R. L., & Park, S. K. (1985). Estimation of fetal weight using head, body and femur measurements - a prospective study. American Journal of Obstetrics & Gynecology, 151, 333-337.

General References

Bricker, L., Neilson, J. P., & Dowswell, T. (2008). Routine ultrasound in late pregnancy (after 24 weeks' gestation). The Cochrane Database of Systematic Reviews, 4, CD001451.

Conde-Agudelo, A., Papageorghiou, A. T., Kennedy, S. H., & Villar, J. (2013). Novel biomarkers for predicting intrauterine growth restriction: a systematic review and meta-analysis. BJOG: An International Journal of Obstetrics & Gynaecology, 120, 681-694.

Ioannou, C., Talbot, K., Ohuma, E., Sarris, l., Villar, J., Conde-Agudelo, A., & Papageorghiou, A. T. (2012). Systematic review of methodology used in ultrasound studies aimed at creating charts of fetal size. BJOG: An International Journal of Obstetrics & Gynaecology, 119, 1425-1439.

Malone, F. D., Canick, J. A., Ball, R. H., Nyberg, D. A., Comstock, C. H., Bukowski, R., . . . D'Alton, M. E., for the First- and Second-Trimester Evalution of Risk (FASTER) Research Consortium. (2005). First-trimester or second-trimester screening, or both, for Down's Syndrome. New England Journal of Medicine, 353(19), 2001-2011.

Sylvan, K., Ryding, E. L., & Rydhstroem, H. (2005). Routine ultrasound screening in the third trimester: A population-based study. Acta Obstetricia et Gynecologica Scandinavica, 84, 1154-1158.

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