Prenatal small head circumference: Which biomarkers best predict microcephaly?

Area of Science:

• Medical imaging
• Prenatal diagnostics
• Pediatric neurology

Background:

• Prenatal ultrasound detection of small head circumference (US-SHC) is a primary indicator for microcephaly.
• Microcephaly diagnosis and prediction require reliable biomarkers for timely intervention.

Purpose of the Study:

• To determine the incidence of small head circumference at birth (b-SHC) and microcephaly at 6 months.
• To identify prenatal biomarkers for predicting postnatal microcephaly.

Main Methods:

• Retrospective study including 55 fetuses with US-SHC and a median postnatal follow-up of 28 months.
• Analysis of fetal brain MRI, head circumference (HC) growth patterns, and genetic testing.

Main Results:

• Prenatal US-SHC predicted b-SHC in 66% of cases and persistent microcephaly at 6 months in 47% of liveborns.
• Fetal brain MRI accurately predicted b-SHC (PPV 83%, NPV 82%), but was less effective for persistent microcephaly (PPV 53%, NPV 75%).
• Prenatal HC growth deceleration significantly predicted both b-SHC (OR=13.86) and persistent microcephaly (OR=13.00). Genetic etiology was found in 44% of microcephaly cases.

Conclusions:

• Prenatal US-SHC is a significant predictor of postnatal microcephaly.
• Prenatal head circumference growth deceleration is a key biomarker for identifying persistent microcephaly.