GAIA Level 3b Prenatally Diagnosed Congenital Microcephaly

**Semantic type:** Classification

**Definition:** GAIA Level 3B Prenatally Diagnosed Congenital Microcephaly is defined by three criteria: first, the fetus is at least 24 weeks gestational age (GA), with GA based on certain or uncertain last menstrual period (LMP) date, with fundal height and no confirmatory first or second trimester ultrasound (US) scan, OR uncertain LMP with second trimester ultrasound, intrauterine insemination (IUI) OR embryo transfer date; second, a head circumference (HC) measurement either 2 standard deviations (SD) below the mean or less than the third percentile according to fetal US examination, using appropriate, standardized reference charts according to GA and gender for the population (e.g. WHO growth reference charts if GA greater than or equal to 37 weeks and Intergrowth-21st reference charts for GA 24 to 36 weeks); third, no confirmation of microcephaly with any additional US or by HC measurement at either birth or autopsy. IMPORTANT NOTICE: The NCI Thesaurus contains biomedical terminologies that NCI does not own or control. This concept contains gender-related content that does not comply with Executive Order 14168.

**Synonyms:** - Global Alignment of Immunization safety Assessment in pregnancy Level 3b Prenatally Diagnosed Congenital Microcephaly - Level 3b Prenatally Diagnosed Congenital Microcephaly