Blind Measurement in Fetal Weight Estimation

Estimating fetal weight using ultrasound is an essential component in fetal medicine and prenatal treatment.

A study that was conducted as a part of the INTERGROWTH-21 project established international standards for fetal growth by documenting 3 measurements of biometry indices, which included head circumference, abdominal circumference, femur length and biparietal diameter (BPD). The measurements were not disclosed to the investigator in order to prevent bias.

In a recent study it was found that use of the average of the 3 biometric measurements compared with a single measurement for the purposes of estimating fetal weight, is more accurate. However, the measurements were disclosed to the investigator.

Currently, no studies have examined whether there blinded measurements are significantly better than non-blinded measurements.

The aim of this study is to compare blinded to non-blinded biometric measurements for estimation of fetal weight.

Woman who are expected to give birth in the next 72 hours will be asked to participate in the study. After singing an informed consent, participants will be randomly allocated to a study group of blinded measurements for estimated fetal weight and a control group of non-blinded measurements. Estimation of fetal weight will be performed using the Hadlock-4 formula in triplicate measurements. In the study group the measurement will be blinded from the sonographer and measurements will be revealed only upon completion of all measurements. In the control group, the same measurements will be conducted without blinding of the measurements during the assessment. Accuracy of estimations will be compared between the two groups.

Inclusion criteria

• Singleton pregnancy
• Gestational age between 37 and 41 weeks
• Expected delivery within 72 hours

Exclusion criteria

• Major Malformations
• Active labor