Understanding Fetal Microcephaly
Thu Feb 05 2026
Fetal Microcephaly has an incidence of 2 to 12 in10,000 births in the USA and can be diagnosed prenatally via ultrasound (in second or early third trimester) or postnatally via measurement of head circumference (HC). Antepartum, this is a unique diagnosis since we are mainly used to using PERCENTAGES for biometrics and for fetal weight, butmicrocephaly is not diagnosed by HC percentage- but by Standard Deviation (SD). Microcephaly has been linked to developmental delay, seizures, as well as feeding, vision and hearing problems. Prognosis depends on the severityof the microcephaly and whether it is associated with other anomalies. What SD is diagnostic of microcephaly? What are the potential etiologies? What genetic syndromes are most associated with true microcephaly? Is fetal cranial MRIrecommended? Listen in for details.
1. Sukenik-Halevy R, Golbary Kinory E, Laron KenetT, Brabbing-Goldstein D, Gilboa Y, Basel-Salmon L, Perlman S. Prenatalgender-customized head circumference nomograms result in reclassification ofmicrocephaly and macrocephaly. AJOG Glob Rep. 2023 Jan 29;3(1):100171. doi:10.1016/j.xagr.2023.100171. PMID: 36864987; PMCID: PMC9972400.
2. SOGC CO (2019) No. 380-Investigation andManagement of Prenatally Identified Microcephaly
3. Fetal Medicine Foundation: Microcephaly; https://fetalmedicine.org/education/fetal-abnormalities/brain/microcephaly
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Fetal Microcephaly has an incidence of 2 to 12 in10,000 births in the USA and can be diagnosed prenatally via ultrasound (in second or early third trimester) or postnatally via measurement of head circumference (HC). Antepartum, this is a unique diagnosis since we are mainly used to using PERCENTAGES for biometrics and for fetal weight, butmicrocephaly is not diagnosed by HC percentage- but by Standard Deviation (SD). Microcephaly has been linked to developmental delay, seizures, as well as feeding, vision and hearing problems. Prognosis depends on the severityof the microcephaly and whether it is associated with other anomalies. What SD is diagnostic of microcephaly? What are the potential etiologies? What genetic syndromes are most associated with true microcephaly? Is fetal cranial MRIrecommended? Listen in for details. 1. Sukenik-Halevy R, Golbary Kinory E, Laron KenetT, Brabbing-Goldstein D, Gilboa Y, Basel-Salmon L, Perlman S. Prenatalgender-customized head circumference nomograms result in reclassification ofmicrocephaly and macrocephaly. AJOG Glob Rep. 2023 Jan 29;3(1):100171. doi:10.1016/j.xagr.2023.100171. PMID: 36864987; PMCID: PMC9972400. 2. SOGC CO (2019) No. 380-Investigation andManagement of Prenatally Identified Microcephaly 3. Fetal Medicine Foundation: Microcephaly; https://fetalmedicine.org/education/fetal-abnormalities/brain/microcephaly