# Electronic nicotine delivery systems (ENDS) use across the menstrual cycle and oral contraceptive regimen: A proof-of-concept intensive longitudinal study

## TL;DR

This study explores how nicotine use via electronic devices changes with hormone levels during the menstrual cycle and with oral contraceptive use.

## Contribution

It introduces the use of intensive longitudinal methods to study ENDS use in relation to hormonal fluctuations and contraceptive regimens.

## Key findings

- ENDS use increased with rising estradiol levels in naturally cycling individuals.
- Oral contraceptive users showed consistent and lower ENDS use.
- Intensive longitudinal methods effectively captured variations in ENDS use over time.

## Abstract

Exogenous and endogenous ovarian hormones (e.g., estradiol, progesterone) may influence nicotine use. Prior research has focused on combustible cigarettes and yielded mixed results, which may be due to a lack of granular assessment of nicotine use across the menstrual cycle or oral contraceptive (OC) regimen. We conducted a small proof-of-concept study on Electronic Nicotine Delivery Systems (ENDS). Our goals were to examine the utility of intensive longitudinal methods to assess ENDS use in a ~month long protocol, and explore ENDS use levels and variability among naturally cycling (NC) individuals and those using OCs.

There were 12 NC participants (Mage=22) and 7 participants using OCs (Mage=21). ENDS occasions were assessed 4 times a day across the protocol.

On average, the NC group completed 77 % and the OC group completed 86 % of ENDS assessments. The average number of missing data was 2.2 days (SD=2.9). Time-Varying Effect Modeling (TVEM) examine changes in links between variables over time. TVEM revealed increases in ENDS use coinciding with rises in estradiol across the menstrual cycle. In contrast, ENDS use was consistent in the OC group.

Preliminary evidence indicates that ENDS use among NC individuals varies as a function of natural fluctuations in ovarian hormones while OCs appear to lower and stabilize ENDS use. Despite the small sample, this study suggests that intensive longitudinal methods are useful for examining links between the menstrual cycle, OCs, and ENDS use. This proof-of-concept research may galvanize mechanistic and intervention research on ovarian hormones and ENDS use.

•ENDS use may vary as a function of naturally occurring fluctuations in estradiol across the menstrual cycle.•Tentative evidence suggests that oral contraceptives may lower and stabilize ENDS use.•Intensive longitudinal methods are useful for examining links between the menstrual cycle/OC regimens and ENDS use.

ENDS use may vary as a function of naturally occurring fluctuations in estradiol across the menstrual cycle.

Tentative evidence suggests that oral contraceptives may lower and stabilize ENDS use.

Intensive longitudinal methods are useful for examining links between the menstrual cycle/OC regimens and ENDS use.