Page Last Updated: May 17, 2026

Release Notes & History🔗

Participant Population (Inclusion/Exclusion Criteria)🔗

HBCD enrolls at least 25% of participants who have more than minimal substance use during pregnancy, including opioids (Si et al. 2024). In addition, HBCD enrollment strategies aimed at yielding a study population that is representative of the individual and geographic characteristics of reproductive-aged women in the United States who had a birth in the past 12 months, and include an adequate comparison group for substance exposed individuals (Nelson et al. 2024). There are siblings enrolled in HBCD, some of whom are twins or triplets (multiples). IDs for multiples are presented in the HBCD Private Release Notes - see Multiple Birth Participants under Visit Information for details.

General Rules Applied to All Data🔗

Exclusions applied to all data	Inactive participants/sessions excluded
Field Conversions	Empty fields are replaced with 'n/a' Sex is set to 'Other' for participants with only one active Visit 1 (V01) visit 'Candidate_Age' values are replaced with 'n/a' for Visit 1 (V01)

Version: R2.0🔗

Release Date: 2026-02-11

Participants

3,605

Total Visits

8,415

V01: 3,545 | V02: 2,310
V03: 1,398 | V04: 679 | V05: 483

By Sex

V02 onwards visit done:
1,159 (F) | 1,271 (M)

V01 Only: 1,175 (Unknown)

Below are the key changes made in Release 2.0 - click to expand each section for details.

Multiple Birth Participants: multiple participants from the same birth (e.g. twins)
Postnatal Recruits (PNR): joined the study after the child is born (complete a modified V01 and V02)

= Concatenated Data - see details

Domain	Instrument	Construct
BEHAVIOR, BIOLOGY, & ENVIRONMENT
Administrative	Study Navigator Contact Form	Recruitment/Retention
Beh & CH-CG Int	CHAOS	Family Organization
	ecPROMIS CH-CG Relationship [1-5 year]	Child-Caregiver Interaction
	ecPROMIS Peer Relationships	Peer Relationships
	ecPROMIS Self-Regulation	Self-Regulation and Flexibility
	FAD (GF6+)	Global Functioning of Family Unit
	ECBQ (VSF)+BI	Early Childhood Behavior + Inhibition
	MAPS-TL [Toddlerhood & Preschool]	Irritability
Biospecimen & Omics	Illumina GDA GWAS	GWAS, EWAS, Transcriptome
Neurocog & Language	Bayley-4 Scales	Child Development (Cognitive, Language, Motor)
	MacArthur-Bates CDI-I	Language Development (Words & Gestures)
	SPM-2 [Toddler]	Sensory Processing/Integration
	Vineland Adaptive Behavior	Adaptive Behavior
Physical Health	Brief Infant Sleep Questionnaire	Sleep
	ecPROMIS Physical Activity/Greenspace	Physical Activity
	ecPROMIS Sleep	Sleep
	Medical History	Medical History
	Infant Nutrition Questionnaire	Nutrition
	Screen-Based Media Use (ScreenQ)	Media Use
	Vision Screener	Vision
Pregnancy & Exposure	ASSIST [V4]	Substance Use Post-Pregnancy
Pregnancy & Exposure	Substance Use Patterns	Substance Use in Pregnancy
Social & Environment	Geocoded Linkage	Neighborhood Measures
	ACEs	Adverse Childhood Experiences
	Child Demographics	Demographics
	Composite Abuse Scale (CABr-SF)	Intimate Partner Violence
	Current Employment	Current Employment
	HOME-21 IT	Child’s Home Environment
	Household Chemical Exposures	Household Chemical Exposures
	Lead Exposures	Lead Exposures
	PACES [<18]	Protective Factors
	Second Hand Smoke Exposure	Second Hand Smoke Exposure
	Transition in Care Screener	Recruitment/Retention
	Vancouver Index of Acculturation (VIA)	Acculturation
BRAIN ACTIVITY & BIOSENSORS
EEG	EEG Acquisition Checklist + Reattempt 1/2	Acquisition Checklists
EEG	ERP SummaryStats	Tabulated HBCD-MADE derivatives
MRI	Pre-Scan Questionnaire	Infant Sleep Environment
Novel Tech & Wearables	Biosensor Receipt & Setup	Administrative

Cross-Modality Updates (MRI & EEG)

Full Raw BIDS Inclusion: All raw BIDS data are now included for both MRI and EEG (previously, only raw data that passed initial raw-data quality control were released).
Additional participant- and visit-level data

MRI-Specific Updates

Enhanced Scans TSV metadata: The session-level sub-[ID]_ses-{V0X}_scans.tsv files now include detailed scanner metadata, including: ScannerManufacturer, ScannerModel, ScannerSoftwareVersion, and ScannerSerialNumber (enables differentiation of multiple scanners within the same site).
Processed data exclusion criteria updated: New procedures have been implemented to remove MRI derivatives with serious data quality issues. See: MR Exclusion Criteria for full details.

Domain	Table/Data	Resolved Known Issue
N/A	General	[1] Resolved lower floating-point value precision in Parquet files by creating all data available in the release in one step (`type_data`=doubles)
	Basic Demographics `sed_basic_demographics`	[1] Removal of invalid response option 2 = Hawaiian from Mother Race (`screen_mother_race`).
		[2] Removed Child Multi-Race (`child_ethnoracial_acs_by_multi_race`) variable due to duplicated coding to Child Multi-Ethnicity (`child_ethnoracial_acs_by_multi_ethnicity`).
		[3] Removed Child Multi-Ethnicity V01 data.
	Visit Level Data `par_visit_data`	[1] Participants who did not withdraw from the study (`participant_withdrawal` = “no”) were assigned a sentinel withdrawal date (`participant_withdrawal_date`) of `12/26/1999`. These values were updated to null for clarity and consistency.
		[2] Removed V02 Biospec substance use flags derived from USDTL urine toxicology (`su_flag_bio_*`) (urine samples not collected at V02).
		[3] Corrected values (replaced 'no' with 'null') of the TLFB substance use flags (`su_flag_tlfb_*`) for participants without a V02 visit.
	Urine toxicology	Restored 'missing' values for urinary cotinine (`bio_bm_biosample_urine__results_results_bio_c_cot_u`) erroneously set to `0` (N = 18).
	SPM-2 `ncl_cg_spm2__inf`	[1] Added age fields - `gestational_age`, `adjusted_age`, and `candidate_age`.
	SPM-2 `ncl_cg_spm2__inf`	[2] Added Status Scores that were missing for all but one subscale.
	APA 1/2 `pex_bm_apa_anger_*`	Added missing T-scores and total scores to Anger subscale (remaining subscales intact).
	TLFB `pex_ch_tlfb`	Added age variable fields - `gestational_age`, `adjusted_age`, and `candidate_age`.
	eHITS `sed_bm_ehits`	Corrected calculation for the two eHits "score" variables (`score` & `total_score`).

Version: R1.1🔗

Release Date: 2025-10-10

Participants

1,426

Total Visits

2,207

V01: 1,426 | V02: 660 | V03: 121

By Sex (V02/V03)

♀ 328 | ♂ 338

1.1 Existing Study Data Updates🔗

Domain	Table/Data	Update/Improvement
Demographics	Basic Demographics `sed_basic_demographics`	Reviewed scoring for AOU and ACS EthnoRacial fields. The multiracial options for ACS – Child – Multi Race (`child_ethnoracial_acs_by_multi_race`) were merged into one due to limited granularity in the child_race field.
Biospecimen & Omics	Nails & Urine Toxicology `bio_bm_biosample_*`	Removed 'Specimen ID’ fields from all Biospecimen tables and time from dates in 'Nails Results.'
Pregnancy Exposure, Including Substance Use	Pregnancy & Infant Health `pex_bm_health*`	Medications are now categorized into more detailed components based on RxNorm IDs to improve clarity and enable more granular analyses. Additional columns specify: Brand Name, Ingredient, Precise Ingredient, and Multiple Active Ingredients.
Social & Environmental Determinants	V01 Demographics `sed_bm_demo`	Added Birth Parent Sexual Orientation variable.
Magnetic Resonance Imaging & Spectroscopy	BrainSwipes QC `img_brainswipes*`	Added QC results missing from R1.0 (N=8).

Basic Demographics

sed_basic_demographics.json
sed_basic_demographics.parquet
sed_basic_demographics.tsv

BioSpecimens

bio_bm_biosample_nails_results.json
bio_bm_biosample_nails_results.parquet
bio_bm_biosample_nails_results.tsv
bio_bm_biosample_nails_results_shadow.parquet
bio_bm_biosample_nails_results_shadow.tsv
bio_bm_biosample_urine.json
bio_bm_biosample_urine_results.parquet
bio_bm_biosample_urine_results.tsv
bio_bm_biosample_urine_results_shadow.parquet
bio_bm_biosample_urine_results_shadow.tsv

SPM-2

ncl_cg_spm2__inf.json
ncl_cg_spm2__inf.parquet
ncl_cg_spm2__inf.tsv
ncl_cg_spm2__inf_shadow.parquet
ncl_cg_spm2__inf_shadow.tsv

TLFB

pex_ch_tlfb.json
pex_ch_tlfb.parquet
pex_ch_tlfb.tsv
pex_ch_tlfb_shadow.parquet
pex_ch_tlfb_shadow.tsv

PEX Health V2 Preg

pex_bm_healthv2_preg.json

1.1 Resolved Known Issues🔗

Basic Demographics (sed_basic_demographics)

Income Not Displayed For All Participants (income)
Missing income fields for subset of subjects now added.

Duplicate Options for 'Mother Race' Variable (screen_mother_race)
Option #3, a duplicate of option #5 for 'Black African American,' now removed.

Gestational Age at Delivery and Mother’s Age at Delivery (<gestational|mother>_age_delivery)
Data from deliveries that occurred after the R1.0 cutoff date of 2025-07-01 (and therefore did not undergo QC) now removed so that only eligible participants with V01 + V02 or V03 are retained.

Mother Ethnicity (screen_mother_ethnicity)
Incorrectly documented as a 4-level variable in the data dictionary, with additional values of 0 and 1 that were not used. The data now only includes the valid levels: 2 (Hispanic) and 3 (Non-Hispanic).

Mother Race & Ethnicity (rc_mother_ethnoracial_aou_race_ethnicity)
Addition of formerly missing response option, "None of these fully describe me/Other."

Visit Level Data (par_visit_data)

Addition of missing Substance Use flags (see details) for alcohol, opioid, cannabis, and nicotine.

Nails & Urine (bio_bm_biosample_{nails|urine})

Addition of formerly missing collection and analysis dates (Collection/Received/Report).

Urine (bio_bm_biosample_urine_results)

Corrected Specific Gravity Variable
Values for the 'Urine Specific Gravity' field (bio_spg_u) have been set to the correct floating point value for the appropriate thousandths format (were previously set to '1' and data type to 'integer'). The corrected variable can now be used for urinary concentration corrections.

Toxicology (Cotinine)
All negative values for urinary toxicology results field bio_c_cot_u are now set to ‘0’ (as negative values are not biologically plausible).

Corrected Negative Gestational Ages
The negative gestational ages for 2 participants in the Urine dataset have been corrected.

The HBCD-MADE resting-state derivative files (processed_data/*_task-RS_powerSummaryStats.csv) have been removed due to errors caused by a previous pipeline bug. These files should not be used for analysis. Users can regenerate the corresponding summary statistics using the scripts provided in HBCD EEG Utilities.

The SPM-2 (ncl_cg_spm2__inf) now includes verified t-scores, originally excluded due to errors in conversion from raw scores.

Health V2- Infancy (pex_bm_healthv2_inf)
Erroneously included descriptive fields 001__00 - 005__00 now removed.

APA 1/2 (pex_bm_apa)
Summary scores and corresponding T-scores are now provided, where appropriate, for Level 2 domains.

EPDS (pex_bm_epds)
Duplicate data for each item (e.g., epds_001 and epds_001_01) now removed.

TLFB (pex_ch_tlfb)
#1 Corrected logic for TLFB substance use flags
Previously, only the alcohol use flag applied the intended criteria (use during or after pregnancy across V01–V02). All substance use flags now follow this logic.

#2 Age Variables Removed
TLFB age variable fields (gestational_age, adjusted_age, and candidate_age) are now removed due to incorrect values.

Version: R1.0🔗

Release Date: 2025-06-26

Participants

1,426

Total Visits

2,207

V01: 1,426 | V02: 660 | V03: 121

By Sex (V02/V03)

♀ 328 | ♂ 338

Participant & Visit Exclusions🔗

Excluded Participants	Participants with no brain rating or brain rating noted as "atypical" Postnatal Recruitment participants Multiple Birth participants
Excluded Visit Data	Visits with 'LaunchPad Complete' Status set to 'Complete' after 2024-07-01.

Instrument & Field Exclusions🔗

Instrument Exclusions

Instrument	Table Name
Biosensor Receipt Form	`sens_ch_rcpt`
EEG Acquisition Checklists	`eeg_ch_chkl` / `eeg_ch_chkl_<1\|2>`
ERICA forms	`mh_cg_erica_<3_7m\|7_9m>` / `mh_cg_erica_fcm_adm_<3_7m\|7_9m>`
GABI Setup/Receipt	`nt_pa_gabi_setup` / `nt_pa_gabi_rcpt`
MRI Checklists & Pre/Post Scan Prep	`mri_ra_chkl_data` / `mri_ra_chkl_scan` / `mri_ra_prep`
NIH Baby ToolBox	`ncl_ch_nbtb`
Participant / RA Feedback	`adm_cg_fb` / `adm_ra_fb`
Urgent Events & Participant Alerts	`adm_fd_urgent` / `admin_alert`
Visit Start / Visit Level Data	`visit_start` / `adm_fd_visitdata`

Instrument Field Exclusions

Table Field(s)	Field Name(s)/Details
Date of Administration	`date_taken`
Examiner	`examiner`
REDCap Complete status	`complete`
Timestamps	`timestamp` / `timestamp_start` / `timestamp_stop` / `timestamp_redcap_locked`
Visit Data	`visit_stage` removed from the `visit_data` category
Breast Feeding History Fields	`ph_cg_phx_i_bfh` – All fields except `001` excluded
Height/Weight/Head Circumference BMI	`ph_ch_anthro` – BMI-related fields removed