## How accurate is Hadlock formula?

The accuracy of any ultrasonic fetal weight formula is dependent on its 95% confidence limit. For example, one of the more popular formulas is the Hadlock HC/AC/FL where the 95% confidence limit is ± 15% and so it is expected that 95% of actual birth weights will be within ± 15% of the predicted birth weight.

## What is Hadlock in ultrasound report?

Estimated fetal weight (EFW) helps inform clinical decision making in patients with preterm premature rupture of membranes (PPROM). The Hadlock IV formula is the most commonly used calculation of EFW using biparietal diameter, head circumference, abdominal circumference, and femur length.

Formula C of Hadlock et al [Hadlock C; log(10) BW = 1.335 – 0.0034(abdominal circumference [AC])(femur length [FL]) + 0.0316(biparietal diameter) + 0.0457(AC) + 0.1623(FL); Am J Obstet Gynecol 1985; 151:333-337] had the best performance according to the bias and precision method.

### How accurate is Hadlock EFW?

In accordance with numerous other studies, our results confirmed that the ultrasound-derived EFW during labor at term is an appropriate diagnostic tool, with an average accuracy of 70% within a relative difference of ±10% to the real birth weight [9,10,11,12,13].

### What is EFW Hadlock in ultrasound?

Figure 1 Association between estimated fetal weight (EFW), derived from model of Hadlock et al. using measurements of head circumference, abdominal circumference and femur length11, and birth weight (BW) in Dataset 1.

What is the normal EFW in pregnancy?

Between 25 and 35 weeks’ gestation, the mean EFW was noticeably larger than was the actual mean birth weight, with discrepancies of up to 16% of birth weight at 30 weeks (predicted birth weight = 1341 g, predicted EFW = 1561 g).

#### What is AC Hadlock measurement?

BPD: biparietal diameter (the diameter between the 2 sides of the head. HC: head circumference. AC: abdominal circumference.

#### What foods increase fetal stomach circumference?

We found maternal fruit and vegetable intake had a positive association with the biparietal diameter of the fetus and infant weight at birth to 6 months. Also, maternal vitamin C intake was positively associated with the abdominal circumference of the fetus and infant birth length.

How far off can a dating ultrasound be?

Ultrasounds performed after 22 weeks gestation are much less reliable in estimating the due date of the baby because the size no longer reflects the gestational age very well. Even average babies can differ by up to 2 to 3 “weeks of growth”.