*2.10.1. The lung area to head circumference ratio*

The lung-to-head circumference ratio (LHR) is a sonographic measure proposed to identify fetuses with congenital diaphragmatic hernia (CDH) that have a poor prognosis. The lung area contralateral to the CDH is measured at the level of *four-chamber view* by manual tracing of the lung which appears to be the most reproducible way of measuring the lung area [30]. The product is divided by the head circumference (HC) to obtain the LHR.

The lung area to head circumference ratio (LHR) = lung area/head circumference.
