Page Last Updated: May 13, 2026

Timeline Follow Back (TLFB)🔗

Table Name	`pex_bm_tlfb`
Construct	Substance Use Before and During Pregnancy
Study Visits	V01, V02
Administration	Child-specific: No Respondent: Birth Parent or Primary Caregiver Method: Staff-administered, in-person (self-administered in Alabama) (10 min estimated duration)
Quality Control	Response distributions are reviewed for outliers and additionally cross-checked with ASSIST V1/V2 to ensure consistency in reported substances.

HBCD was designed to enable the characterization of the known fluctuation in substance use across the perinatal period critical for advancing prevention and intervention (Massey et al., 2021, Bandoli et al., 2022, Si et al., 2024).

Moreover, characterization of between- and within-person variability in substance use has been shown to enhance the sensitivity and specificity of risk prediction (Massey et al., 2021, Massey et al., 2018). Thus, the characterization of patterns or trajectories of use should be considered over the use of dichotomous exposure characterization. Another gap in literature concerns the extent, nature, and implications of polysubstance use during pregnancy since individual substances have primarily been examined alone in prior research (Massey et al., 2018). The power and scope of HBCD avails a unique opportunity to understand the prevalence and implications of such ‘real world’ patterns of substance use.

Sampling Window and Coverage Limitations
The sampling covers specific weeks before pregnancy (Weeks 1-2) and during pregnancy (Weeks 3-9). Consequently, substance use reported outside these weeks may not appear in the TLFB, and a positive biospecimen may lack corresponding TLFB data for the same reason. This sampling approach balances participant burden (avoiding a full 40-week TLFB) with capturing key pregnancy phases when behaviors often shift, such as before and after pregnancy recognition and in late pregnancy.

Notes on Reporting Format and Data Variability
Participants were asked to report occasions (except cigarettes/cigarillos and drinks, reported as number), but some substances (e.g. electronic cigarette devices) are difficult to report in occasions and have outliers.

Instrument Details🔗

The original Timeline Follow Back instrument is designed to assess substance use over the 7 days preceding survey administration. For HBCD, the TLFB was adapted, triggered by responses on the ASSIST, to collect information on substance use before and during pregnancy.

Participants who reported any substance use in the three months prior to or during pregnancy completed a TLFB interview for each substance reported on the ASSIST. Use was disaggregated by product type (e.g., edible cannabis products), and participants provided estimates for nine distinct weeks of use. For each week, the number of occasions of use per day was captured for all products except for cigarettes and cigarillos (number per day) and alcohol (number of single servings per day). The nine sampled weeks were distributed across two study visits:

Version 1	Period 1: Two Weeks Pre-LMP (Weeks 1–2, four through two weeks pre-LMP) - Pre-pregnancy use Period 2: Four Weeks Post-LMP (Weeks 3–6, two through six weeks post-LMP) - Early pregnancy use Period 3: Last Week (Week 7, the week prior to Visit 1) - Current use (at time of administration)
Version 2	Period 4: Last Two Weeks Before Delivery (Weeks 8–9)

Postnatal recruits (participants enrolled in the study postnatally) are administered an adapted Version 3 of the TLFB, which includes all of the four time periods above in a single administration. Period 3 in this version captures Week 7 as the week spanning LMP + 19 weeks to LMP + 20 weeks.

Version 3

Period 1: Two Weeks Pre-LMP (Weeks 1–2, four through two weeks pre-LMP) - Pre-pregnancy use
Period 2: Four Weeks Post-LMP (Weeks 3–6, two through six weeks post-LMP) - Early pregnancy use
Period 3: Week 7, captured as the week spanning LMP + 19 weeks pre-LMP + 20 weeks
Period 4: Last Two Weeks Before Delivery (Weeks 8–9)

References🔗

Bandoli, G., Kable, J. A., Coles, C. D., Del Campo, M., Suttie, M., & Chambers, C. D. (2022). Trajectories of prenatal alcohol exposure and behavioral outcomes: Findings from a community-based sample. Drug and Alcohol Dependence, 233(109351), 109351. https://doi.org/10.1016/j.drugalcdep.2022.109351

Massey, S. H., Pool, L. R., Estabrook, R., Level, R. A., Shisler, S., Stacks, A. M., Neiderhiser, J. M., Espy, K. A., Wakschlag, L. S., Eiden, R. D., & Allen, N. B. (2022). Within-person decline in pregnancy smoking is observable prior to pregnancy awareness: Evidence across two independent observational cohorts. Addiction Biology, 27(6), e13245. https://doi.org/10.1111/adb.13245

Massey, S. H., Allen, N. B., Pool, L. R., Miller, E. S., Pouppirt, N. R., Barch, D. M., Luby, J., Perlman, S. B., Rogers, C. E., Smyser, C. D., & Wakschlag, L. S. (2021). Impact of prenatal exposure characterization on early risk detection: Methodologic insights for the HEALthy Brain and Child Development (HBCD) study. Neurotoxicology and Teratology, 88(107035), 107035. https://doi.org/10.1016/j.ntt.2021.107035

Massey, S. H., Mroczek, D. K., Reiss, D., Miller, E. S., Jakubowski, J. A., Graham, E. K., Shisler, S. M., McCallum, M., Huestis, M. A., Ganiban, J. M., Shaw, D. S., Leve, L. D., Eiden, R. D., Stroud, L. R., & Neiderhiser, J. M. (2018). Additive drug-specific and sex-specific risks associated with co-use of marijuana and tobacco during pregnancy: Evidence from 3 recent developmental cohorts (2003-2015). Neurotoxicology and Teratology, 68, 97–106. https://doi.org/10.1016/j.ntt.2018.06.002

Si, Y., Bandoli, G., Cole, K. M., Daniele Fallin, M., Stuart, E. A., Gurka, K. K., Althoff, K. N., Thompson, W. K., & the HBCD Design Workgroup and Biostatistics Workgroup. (2024). Advancing high quality longitudinal data collection: Implications for the HEALthy Brain and Child Development (HBCD) Study design and recruitment. Developmental Cognitive Neuroscience, 69(101432), 101432. https://doi.org/10.1016/j.dcn.2024.101432

Sobell, L., & Sobell, M. (2000). Alcohol timeline follow-back (TLFB). In Handbook of psychiatric measures (p. 477). American Psychiatric Association.