Abstract P201: Early Life Exposure To Environmental Tobacco Smoke And Cardiometabolic Diseases In Middle Age: A 4-decade Follow-up Study Of The Collaborative Perinatal Project
Authors: Niu Zhongzheng , Mu Lina , Buka Stephen , Loucks Eric , Kubzansky Laura , Wang Meng , Tian Lili , Wen Xiaozhong 
Published: May 2021

Introduction:
Environmental tobacco smoke (ETS) is a major source of indoor air pollution and has been associated with cardiovascular diseases (CVD) risks. There is little research on the associations of ETS exposure in early life with CVD risks in later life.

Hypothesis:
We hypothesized that ETS exposures in the uterus, childhood, and teenage increase midlife CVD risks.

Methods:
For 1,623 offspring born in 1959-1966 at two sites from the Collaborative Perinatal Project, we defined intrauterine ETS exposure in each trimester if the mother smoked (1-19 or ≥20 cigs/day). ETS exposure in each year from birth to 18 years was quantified by total daily-average hours of parents smoking weighted by daily packs from a questionnaire at the adult follow-up (mean age: 39 years). Ever diagnoses of diabetes (cumulative incidence: 3.0%), heart diseases (1.5%), hypertension (17.3%), and high cholesterol (25.3%) until adult follow-up were reported. Cardiometabolic diseases (CMD, cumulative incidence: 35.4%) were defined as any diagnosis. We estimated odds ratio (OR) for CMD by ETS exposures in each trimester adjusting for prenatal factors (maternal SES, pre-pregnancy BMI, parity, newborn sex); additionally adjusted for maternal smoking in pregnancy, birth weight, and gestational age for ETS exposure from birth to 18 years. We also stratified the analyses by adult smoking status.

Results:
Exposure to ≥20 cigs/day in the 1
st
(OR: 1.52, 95% CI: 1.02-2.26) and 2
nd
(OR: 1.50, 95% CI: 1.01-2.24) trimester was significantly associated with hypertension compared to none exposure, and the associations were stronger in adult offspring who were smokers. Among the 70% of participants who reported childhood ETS exposure, the average exposure was 8.5 smoker-hours/day and 10.5 smoker-hour*packs/day (HP/Day), with a declining trend from birth to 18 years. ETS exposure (per SD increment) in early life from birth to 18 years, separately or cumulatively (OR=1.24, 95% CI: 1.07-1.43), was associated with higher odds of adult hypertension. ETS exposure in teenage (11-18 years, OR=1.26, 95% CI: 1.05-1.50), but not in childhood (birth to 10 years, OR=1.18, 95% CI: 0.96-1.45), was associated with higher odds of a combination of adult heart disease and diabetes, which was more striking in adult non-smokers than smokers. Odds of adult CMD increased by 13% (95% CI: 1%-28%) for each SD (about 10 HP/Day) increment in ETS in the whole childhood and by 16% (95% CI: 3%-30%) in teenage. The results for smoker-hours/day were similar to those for smoker-hour*packs/day.

Conclusions:
Intrauterine exposure to maternal smoking and ETS exposures (time and total amount) from birth to 18 years increase the risk of adult hypertension. ETS exposure in early life may also increase the risk of adult cardiometabolic diseases. Teenage may be a sensitive window for elevated risk of adult heart diseases and diabetes associated with ETS exposure.