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

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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

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.




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
Major equipment No
Specialized training No
Specialized requirements for biospecimen collection No
Average time of greater than 15 minutes in an unaffected individual No
Mode of Administration

Medical record abstraction


Adolescent, Adult, Pregnancy


Pregnant women aged 18-40

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.



caDSR Form PhenX PX241501 - Fetal Growth Assessment Percentiles For Us Populatio 6873323 caDSR Form
Derived Variables


Process and Review

Not applicable.

Protocol Name from Source

Hadlock, F.P., et al. Racial/ethnic standards for fetal groth: the NICHD Fetal Growth Studies. Am J Obstet Gynecol, 2015


Buck Louis, G. M., Grewal, J., Albert, P. S., Sciscione, A., Wing, D. A., Grobman, W. A., Newman, R. B., Wapner, R., DAlton, 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., . . . DAlton, M. E., for the First- and Second-Trimester Evalution of Risk (FASTER) Research Consortium. (2005). First-trimester or second-trimester screening, or both, for Downs 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.

Protocol ID


Export Variables
Variable Name Variable IDVariable DescriptiondbGaP Mapping
PX241501060000 Abdominal circumference (AC): N/A
PX241501020200 Gestational Age: N/A
PX241501020100 Gestational Age: N/A
PX241501030000 Biometric measures as they appear on the more
ultrasound report: show less
PX241501040000 Bi-parietal diameter (BPD): N/A
PX241501080000 Estimated Fetal Weight (EFW): N/A
PX241501070000 Femur length (FL): N/A
PX241501050000 Head circumference (HC): N/A
PX241501110000 Estimated Fetal Weight: N/A
PX241501100200 Gestational Age: N/A
PX241501100100 Gestational Age: N/A
PX241501090000 Date of ultrasound: N/A
PX241501010000 Date of ultrasound: N/A
Measure Name

Fetal Growth Assessment - Percentiles for U.S. Populations

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.


pregnancy, gestational age, fetal ultrasound, fetal weight, due date, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health

Measure Protocols
Protocol ID Protocol Name
241501 Fetal Growth Assessment - Percentiles for U.S. Populations

There are no publications listed for this protocol.