Fig 4. Crude comparison of biases associated with alternative methods of estimating gestational age.
GA: gestational age estimated from CRL biometry. CRL: crown-rump length. SFH: symphysis fundal height. HC: head circumference, measured at 25, 30, 35 or 40 weeks gestation. Solid red vertical lines delineate cut-offs for preterm (<37 weeks) and post-term (>41 weeks) newborns, and small for gestational age (Z-score <-1.28) newborns. Dotted red horizontal lines are mirrors of HC bias to facilitate visual comparison.