GAIA Level 2a Postnatally Diagnosed Congenital Microcephaly

**Semantic type:** Classification

**Definition:** GAIA Level 2a Postnatally Diagnosed Congenital Microcephaly is defined by three criteria: first, a live birth, stillbirth, or spontaneous or therapeutic abortion of at least 24 weeks gestational age (GA), with GA assessed by either a certain last menstrual period (LMP) date with confirmatory 1st trimester (less than 14 weeks) or 2nd trimester ultrasound (US) scan OR 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 as assessed by GA and gender, using appropriate, standardized reference charts 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, one of the following requirements is met: a) the measurement is taken within the first 24 hours after birth or at the end of the pregnancy taking into consideration the molding of the head; OR b) the measurement is taken greater than 36 hours and up to 6 weeks after birth or the end of the pregnancy with no apparent post-natal insult resulting in microcephaly. 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 2a Postnatally Diagnosed Congenital Microcephaly - Level 2a Postnatally Diagnosed Congenital Microcephaly