Age Variable Definitions🔗

Fields reporting age in the tabulated datainstrument and derived data
(tabulated format) include global, single-point (i.e. static) variables in Basic Demographics (e.g. Maternal Age at V01), and instrument-specific variables for age that vary depending on the date of administration for a given instrument. In the raw file-based data (EEG, magnetic resonance imaging/spectroscropy, and motion sensor data), fields reporting age vary depending on the date of data acquisition, reported in the session- and scan-level .tsv files. See details for each below.

Basic Demographics🔗

Tabulatedinstrument and derived data
(tabulated format) Basic Demographics data (sed_basic_demographics) includes variables derived across instruments, with the following set of variables reporting age. These are single-point, static variables (i.e. they do not change over time) that should be present and consistent across all visits unless data beyond visit V01 is not available.

Name	Variable Name	Description	Unit & Calculation
Maternal Age at V01 (MAV01)	mother_age_v01	Birth parent's age, obtained from the scheduled date of the V01 visit	Years (to two decimal places), with fractional years calculated by dividing the number of whole months (rounded down) by 12
Maternal Age at Delivery (MAD)	mother_age_delivery	Birth parent's age at the time of their child's delivery (date of birth)	Years (to two decimal places), with fractional years calculated by dividing the total whole months (rounded down) by 12
Gestational Age at Delivery (GAD)	gestational_age_delivery	Time elapsed between the first day of the birth parent's LMP last menstrual period, estimated as EDD minus 280 days and the child's date of birth	Whole weeks, rounded down to the nearest week

Tabulated Instrument Data🔗

All tabulated data include the following fields that report the age of the child participants at the time of instrument administration.

Name	Variable Name	Description	Unit & Calculation	Visit(s)
Gestational Age at Administration (GAA)	{instrument}_gestational_age	Time from the first day of the birth parent's LMP Last menstrual period, estimated as EDD minus 280 days to the instrument administration date. Max 4 week variation Varies no more than 4 weeks across protocol elements except when protocol exceptions were granted	Whole weeks, rounded down to the nearest week	V01 only
Chronological Age at Administration	{instrument}_candidate_age	Time from birth (with the birthdate jittered up to 7 days to mitigate identification risks) to the date of instrument administration	Years Reporting in years, rather than months, ensures consistency across developmental stages (e.g., toddlerhood, childhood), while three-decimal precision compensates for birthdate adjustments, yielding values closer to actual age. (to 3 decimal places), calculated by dividing the total days elapsed (rounded down) by 365.25	V02 onward
Adjusted Chronological Age at Administration (ACAA)	{instrument}_adjusted_age	Time elapsed between the EDD estimated date of delivery and date of instrument administration	Whole weeks, rounded down to the nearest week	V02 onward

Raw File-Based Data🔗

Raw file-based dataimaging and biosignal data
(varied formats) includes MRI, MRS, EEG, and motion/accelerometry data acquired from the child participants (see details). For visits V02 onward (data unavailable for prenatal visit V01), the age of the child at the time of data acquisition is reported in the session- and scan-level .tsv files that accompany these data (see details).

Name	Variable Name	Description	Unit & Calculation	Visit(s)
Adjusted Age at Time of Scan	age_adjusted	Time from EDD estimated date of delivery to the date of data acquisition	Days (not rounded)	V02 onward
Chronological Age at Time of Scan	age	Time from birth (with the birthdate jittered up to 7 days to mitigate identification risks) to the date of data acquisition.	Years Reporting in years, rather than months, ensures consistency across developmental stages (e.g., toddlerhood, childhood), while 3-decimal precision compensates for birthdate adjustments, yielding values closer to actual age. (to three decimal places), calculated by dividing the total days elapsed (rounded down) by 365.25	V02 onward