Established and Proposed Microcephaly Case Definitions
| Origin of Case Definition | Microcephaly Case Definition |
|---|---|
| Brazil MOH 1 | Term: OFC ≤33.0 cm for all infants Preterm: OFC ≤3rd percentile Fenton GC adjusted for GA and gender |
| Brazil MOH 2 | Term: OFC ≤32.0 cm for all infants Preterm: OFC ≤3rd percentile Fenton GC adjusted for GA and gender |
| PAHO 1 | Term: OFC <−2 SD WHO GC for males (<31.9 cm) and females (<31.5 cm) Preterm: OFC <−2 SD Fenton GC adjusted for GA and gender |
| PAHO 2 | Term: OFC <3rd percentile WHO GC for males (<32.0 cm) and females (31.6 cm) Preterm: OFC <3rd percentile Fenton GC adjusted for GA and gender |
| WHO 1 | Unknown GA, suspected term: OFC <−2 SD WHO GC 0–6 days: males: <31.9 cm; females: <31.5 cm 7–13 days: males: <32.7 cm; females: <32.2 cm |
| WHO 2 | Unknown GA, suspected term: OFC <3rd percentile WHO GC 0–6 days: males: <32.0 cm; females: <31.6 cm 7–13 days: males: <32.8 cm; females: <32.4 cm |
| WHO 3 | Unknown GA, suspected term: OFC <−3 SD WHO GCa 0–6 days: males: <30.7 cm; females: <30.3 cm 7–13 days: males: <31.5 cm; females: <31.1 cm |
| Fenton 1 | All infants: <−2 SD Fenton GC adjusted for gender and estimated GA |
| Fenton 2 | All infants: <3rd percentile Fenton GC adjusted for gender and estimated GA |
| Fenton 3 | All infants: <−3 SD Fenton GC adjusted for gender and estimated GAa |
Abbreviations: GA, gestational age; GC, growth curve; MOH, Ministry of Health; OFC, occipital frontal head circumference; PAHO, Pan American Health Organization; SD, standard deviation; WHO, World Health Organization.
↵a <-3 SD defines severe microcephaly.