Prenatal microcephaly: can we be more accurate?

Consultation regarding isolated fetal microcephaly is especially difficult in a genetically heterogeneous population, as one of the factors associated with head circumference difference is ethnicity. The study presents four women referred to the neuro-fetal clinic for isolated fetal microcephaly. All fetuses had normal chromosomes, no structural abnormalities, or evidence of intrauterine infection or intoxication. Their head circumference measurements were 2 to 3 standard deviations below average for age on repeat ultrasound and fetal magnetic resonance imaging. Striking differences in chart placements were found between different professionals using different charts. In all children, measured head circumference after birth/termination was within normal limits. This study suggests that national charts should be built measuring fetal size adjusted for ethnicity and based on a genetically heterogeneous population. The charts should be customized between different professionals assessing prenatal and postnatal head circumference.