Comparison of the Hadlock and INTERGROWTH formulas for calculating estimated fetal weight in a preterm population in France

Am J Obstet Gynecol. 2018 Nov;219(5):476.e1-476.e12. doi: 10.1016/j.ajog.2018.08.012. Epub 2018 Aug 14.


Background: Accurate estimation of fetal weight is needed for growth monitoring and decision-making in obstetrics; the INTERGROWTH project developed an estimated fetal weight formula to construct new intrauterine growth standards.

Objective: We sought to compare the accuracy of the Hadlock and INTERGROWTH formulas for the estimation of fetal weight among preterm infants.

Study design: Using the EPIPAGE 2 population-based study of births between 22-34 weeks of gestation, we included 578 nonanomalous singleton fetuses with an ultrasound-to-delivery interval <2 days. We used abdominal circumference, head circumference, and femur length to calculate estimated fetal weight with Hadlock formula and abdominal and head circumferences to calculate estimated fetal weight according to INTERGROWTH. The mean percentage errors and the proportions of estimated fetal weight measures within ±10% of birthweight were compared between the 2 methods.

Results: Mean (SD) gestational age and birthweight were 29.1 (SD 2.7) weeks and 1219 (SD 489) g. Mean (SD) percentage errors for Hadlock and INTERGROWTH were significantly different: -0.7 (SD 10.1) and -3.5 (SD 11.6), respectively (P < .001), and more infants were classified within ±10% of their birthweight with Hadlock compared to INTERGROWTH (68.7% vs 57.8%, P < .001). The INTERGROWTH formula overestimated birthweight at 22-23 weeks compared to Hadlock [mean errors of 18.8 (SD 13.6) vs 5.5 (SD 10.2)] and underestimated birthweight >28 weeks: at 29-31 weeks, mean errors were -5.8 (SD 10.9) for INTERGROWTH and -0.6 (SD 10.4) for Hadlock.

Conclusion: Hadlock estimated fetal weight formula was more accurate than INTERGROWTH formula for fetuses delivered between 22-34 weeks of gestation. Our results support continued use of Hadlock formula in France and raise questions about the applicability of INTERGROWTH intrauterine growth standards.

Keywords: Hadlock; INTERGROWTH; estimated fetal weight; ultrasound; very preterm.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abdomen / diagnostic imaging
  • Abdomen / embryology
  • Adult
  • Birth Weight
  • Ethnic Groups
  • Female
  • Femur / diagnostic imaging
  • Femur / embryology
  • Fetal Development
  • Fetal Weight*
  • France
  • Gestational Age
  • Growth Charts
  • Head / diagnostic imaging
  • Head / embryology
  • Humans
  • Infant, Newborn
  • Infant, Newborn, Diseases / diagnosis
  • Infant, Premature*
  • Pregnancy
  • Prenatal Diagnosis / methods*
  • Prenatal Diagnosis / standards*
  • Reproducibility of Results
  • Ultrasonography, Prenatal