Age Variable Definitions🔗
This page defines how age is represented for the child and birth parent across HBCD datasets.
Basic Demographics🔗
The Basic Demographics table contains global, static variables derived across administrative and instrument data. Age variables include the child's Gestational Age at Delivery as well as age variables specific to the birth parent, including Maternal Age at V01 and Maternal Age at Delivery. See documentation under Basic Demographics for details.
Tabulated Instrument Data🔗
Age variables within tabulated instrument data describe the child’s age at instrument administration.
Note:
- LMP (first day of the birth parent's last menstrual period) is estimated as EDD (Estimated Date of Delivery) − 280 days
- Adjusted Chronological Age may be negative if collected prior to the EDD
| Variable Name | Variable Label | Description | Visit |
|---|---|---|---|
| Gestational Age at Administration | gestational_age |
Number of weeks (rounded down) between LMP and the V01 administration date. May vary by ≤4 weeks across protocol elements. | V01 |
| Chronological Age at Administration | candidate_age |
Age in years (3 decimal places) at administration based on a jittered DOB (±7 days) to protect participant privacy. Calculated as: total elapsed days (rounded down) ÷ 365.25 | V02+ |
| Adjusted Chronological Age at Administration | adjusted_age |
Number of weeks (rounded down) between EDD and the administration date. Aligns preterm and full-term infants to a common developmental reference. | V02+ |
File-Based Data🔗
Age variables within file-based data, provided within higher-level session- and scan-level metadata, describe the child’s age on day of scan/data acquisition for MR, EEG, and biosensor data.
| Variable Name | Variable Label | Description | Visit |
|---|---|---|---|
| Adjusted Age at Time of Scan | age_adjusted |
Time in days between EDD and the acquisition date | V02+ |
| Chronological Age at Time of Scan | age |
Age in years (3 decimal places) at acquisition, based on a jittered DOB (±7 days) to protect participant privacy. Calculated as: total elapsed days (rounded down) ÷ 365.25 | V02+ |