Associations between adult and childhood secondhand smoke exposures and fecundity and fetal loss among women who visited a cancer hospital

Unraveling the link: environmental tobacco smoke exposure and its impact on infertility among American women (18-50 years)

Purpose

The detrimental effects of environmental tobacco smoke (ETS) on women's reproductive health have been widely recognized. However, the detailed association between exposure to environmental tobacco smoke and the incidence of infertility remains under-explored. This investigation focuses on exploring this potential connection.

Methods

For this analysis, we extracted data from the US National Health and Nutrition Examination Survey (NHANES) database, covering the years 2013 to 2018, focusing on individuals with recorded serum cotinine levels and infertility information. ETS exposure and fertility status were analyzed as independent and dependent variables, respectively. We applied weighted multivariate logistic regression method to evaluate the impact of ETS on infertility, including subgroup analyses for more detailed insights.

Results

The study encompassed 3,343 participants. Logistic regression analysis revealed a notable positive correlation between ETS exposure and infertility, with an odds ratio (OR) of 1.64 (95% Confidence Interval [CI]: 1.14-2.36). We observed a non-linear relationship between ETS exposure and infertility risk. Notably, infertility risk increased by 64% in serum cotinine levels above 0.136 compared to that in serum cotinine levels below 0.011. Further, subgroup analysis and interaction tests showed consistent results across different segments, underscoring the robustness of the ETS-infertility link.

Conclusion

Our findings suggest that environmental tobacco smoke exposure may be a contributing factor to infertility. These results reinforce the recommendation for women in their reproductive years to avoid ETS exposure, especially when planning for pregnancy.

Indoor and outdoor air pollution and couple fecundability: a systematic review

BACKGROUND

Air pollution is both a sensory blight and a threat to human health. Inhaled environmental pollutants can be naturally occurring or human-made, and include traffic-related air pollution (TRAP), ozone, particulate matter (PM) and volatile organic compounds, among other substances, including those from secondhand smoking. Studies of air pollution on reproductive and endocrine systems have reported associations of TRAP, secondhand smoke (SHS), organic solvents and biomass fueled-cooking with adverse birth outcomes. While some evidence suggests that air pollution contributes to infertility, the extant literature is mixed, and varying effects of pollutants have been reported.

OBJECTIVE AND RATIONALE

Although some reviews have studied the association between common outdoor air pollutants and time to pregnancy (TTP), there are no comprehensive reviews that also include exposure to indoor inhaled pollutants, such as airborne occupational toxicants and SHS. The current systematic review summarizes the strength of evidence for associations of outdoor air pollution, SHS and indoor inhaled air pollution with couple fecundability and identifies gaps and limitations in the literature to inform policy decisions and future research.

SEARCH METHODS

We performed an electronic search of six databases for original research articles in English published since 1990 on TTP or fecundability and a number of chemicals in the context of air pollution, inhalation and aerosolization. Standardized forms for screening, data extraction and study quality were developed using DistillerSR software and completed in duplicate. We used the Newcastle-Ottawa Scale to assess risk of bias and devised additional quality metrics based on specific methodological features of both air pollution and fecundability studies.

OUTCOMES

The search returned 5200 articles, 4994 of which were excluded at the level of title and abstract screening. After full-text screening, 35 papers remained for data extraction and synthesis. An additional 3 papers were identified independently that fit criteria, and 5 papers involving multiple routes of exposure were removed, yielding 33 articles from 28 studies for analysis. There were 8 papers that examined outdoor air quality, while 6 papers examined SHS exposure and 19 papers examined indoor air quality. The results indicated an association between outdoor air pollution and reduced fecundability, including TRAP and specifically nitrogen oxides and PM with a diameter of ≤2.5 µm, as well as exposure to SHS and formaldehyde. However, exposure windows differed greatly between studies as did the method of exposure assessment. There was little evidence that exposure to volatile solvents is associated with reduced fecundability.

WIDER IMPLICATIONS

The evidence suggests that exposure to outdoor air pollutants, SHS and some occupational inhaled pollutants may reduce fecundability. Future studies of SHS should use indoor air monitors and biomarkers to improve exposure assessment. Air monitors that capture real-time exposure can provide valuable insight about the role of indoor air pollution and are helpful in assessing the short-term acute effects of pollutants on TTP.

Early life exposure to tobacco smoke and ovarian cancer risk in adulthood

BACKGROUND

Ovarian cancer risk in adulthood may be affected by early life exposure to tobacco smoke. We investigated this relationship in two large prospective cohorts, the Nurses' Health Study (NHS) and NHSII.

METHODS

In total, analyses included 110 305 NHS participants (1976-2016) and 112 859 NHSII participants (1989-2017). Self-reported early life smoking exposures were queried at baseline or follow-up questionnaires. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of ovarian cancer overall and by tumour histotype.

RESULTS

Overall, ovarian cancer risk was not different among participants whose mothers did versus did not smoke during pregnancy (HR = 1.05, 95% CI: 0.87-1.27); however, an increased risk was observed among women who themselves were never smokers (HR = 1.38, 95% CI: 1.05-1.81) but not among ever smokers (HR = 0.86, 95% CI: 0.66-1.14; Pheterogeneity = 0.02). Compared with women who never smoked, ovarian cancer risk was similar for women who started to smoke at age <18 (HR = 0.98, 95% CI: 0.86-1.11) or ≥18 (HR = 1.02, 95% CI: 0.93-1.12). These associations did not differ by histotype (Pheterogeneity ≥0.35). Parental smoking in the home during childhood/adolescence was related to a 15% increased risk of ovarian cancer in adulthood (HR = 1.15, 95% CI: 1.04-1.27) and this association was suggestively stronger among women with non-serous/low-grade serous tumours (HR = 1.28, 95% CI: 1.02-1.61) versus high-grade serous/poorly differentiated tumours (HR = 1.09, 95% CI: 0.93-1.28; Pheterogeneity = 0.25).

CONCLUSIONS

Exposure to parental tobacco smoke in the home, but not early initiation of smoking, was associated with a modest elevated risk of ovarian cancer. Further investigations are required to confirm these findings and elucidate underlying mechanisms.

Systematic review and meta-analysis of female lifestyle factors and risk of recurrent pregnancy loss

It is known that lifestyle factors affect sporadic miscarriage, but the extent of this on RPL (recurrent pregnancy loss) is less well known. A systematic review and meta-analysis was performed to assess the associations between lifestyle factors and RPL. Studies that analysed RPL in the context of BMI, smoking, alcohol and caffeine intake were included. The primary and secondary outcomes were odds of having RPL in the general population and odds of further miscarriage, respectively. Underweight and women with BMI > 25 are at higher odds of RPL in the general population (OR 1.2, 95% CI 1.12-1.28 and OR 1.21, 95% CI 1.06-1.38, respectively). In women with RPL, having BMI > 30 and BMI > 25 has increased odds of further miscarriages (OR 1.77, 95% CI 1.25-2.50 and OR 1.35, 95% CI 1.07-1.72, respectively). The quality of the evidence for our findings was low or very low. Being underweight and BMI > 25 contributes significantly to increased risk of RPL (general population). BMI > 25 or BMI > 30 increases the risk of further miscarriages (RPL population). Larger studies addressing the effects of alcohol, cigarette smoking and caffeine on the risk of RPL with optimisation of BMI in this cohort of women are now needed.

Are older adults' home exposures to secondhand smoking during earlier life stages associated with current health status and life satisfaction in China? A multilevel approach

Secondhand smoking (SHS) has become a critical challenge in Chinese society, and progress on SHS prevention remains unknown. There is little knowledge targeting Chinese older adults generally to investigate the associations between SHS exposure experiences during earlier life stages and health-related measurements. Using cross-sectional data from a nationally representative data set, the 2014 wave of the Chinese Longitudinal Healthy Longevity Survey (n = 4,414), multilevel logistic regression models with random effects for Chinese provinces were used for analyses. Two health-related measurements included self-reported health status and life satisfaction. All regression models included the same set of predictors and covariates with socioeconomic factors and basic biological information. Approximately 40% and 47% of older adults reported SHS exposure in childhood and in younger adulthood at home, respectively. Older adults with SHS exposure in childhood had lower odds of reporting better health status, compared with those who did not have such exposure (adjusted odds ratio [AOR] = 0.69, 95% CI [0.55, 0.86], p < .01). However, life satisfaction was not associated with any SHS exposure experiences. Policy makers and public health practitioners should continue to investigate the long-term effect of SHS exposure on human health, including older adults. Policy regarding SHS prevention should be enhanced.

Childhood secondhand smoke exposure and pregnancy loss in never smokers: the Guangzhou Biobank Cohort Study

OBJECTIVE

Studies of secondhand smoke (SHS) exposure especially childhood SHS exposure and pregnancy loss are limited. We used baseline data of the Guangzhou Biobank Cohort Study (GBCS) to examine the association of childhood SHS exposure with a history of pregnancy loss.

METHODS

Never smoking women aged 50 years or above in GBCS from 2003 to 2008 were included. Propensity score matching (PSM) was used to control for confounding. Negative binomial regression and logistic regression were used to examine the association of childhood SHS, assessed by number of smokers in childhood household and frequency of exposure, with past pregnancy loss.

RESULTS

Of 19 562 women, 56.7% (11 096) had SHS exposure during childhood. In negative binomial regression, after adjusting for age, education, past occupational dust exposure, past home fuel exposure, oral contraceptive, adulthood SHS exposure, age at first pregnancy and age at first menarche, compared to non-exposure, the incidence rate ratio of one more pregnancy loss was 1.20 (95% CI1.05 to 1.37) in those who lived with ≥2 smokers in the same household, and 1.14 (95% CI 1.04 to 1.25) in those exposed ≥5 times/week. After similar adjustment, logistic regression showed that the OR of pregnancy loss ≥2 times (versus 0 to 1 time) was 1.25 (95% CI 1.00 to 1.57) and 1.20 (95% CI 1.03 to 1.40) for high density (≥2 smokers in the same household) and frequency (≥5 times/week) of childhood exposure, respectively.

CONCLUSIONS

Childhood SHS exposure was associated with higher risks of pregnancy loss in middle-aged and older Chinese women.

Major Disease Prevalence and Menstrual Characteristics in Infertile Female Korean Smokers

We investigated the prevalence of smoking and factors associated with smoking in infertile Korean women. Smoking status, education, occupation, personal habits, past medical history, current illness, stress level, and menstrual characteristics were collected from self-report questionnaires. The Beck Depression Inventory (BDI) was used to assess the degree of depression. Data on the causes of infertility and levels of six reproductive hormones were collected from medical records. Among 785 women less than 42 years of age, the prevalence of current, secondhand, past, and never smokers were 12.7%, 45.7%, 0.9%, and 40.6%, respectively. Primary infertility was more frequent in secondhand smokers. Causes of infertility were similar among current, secondhand, and never smokers. Current smokers were less educated (P < 0.001) and more likely to consume alcohol than secondhand or never smokers (P < 0.001). Secondhand smokers slept less than current smokers (P = 0.041). Among several major diseases, only the prevalence of diabetes mellitus (4.0%) was significantly higher in current smokers than in secondhand smokers (0.0%, P = 0.002) or never smokers (0.6%, P = 0.031). The self-reported prevalence of depression, and the degree of depression were similar among women with different smoking statuses. There were no differences in menstrual characteristics or serum levels of six reproductive hormones between current, secondhand, and never smokers, even after excluding women with polycystic ovary syndrome. In conclusion, education/employment status, alcohol drinking, and the prevalence of primary infertility and diabetes mellitus were significantly different according to smoking status among infertile women.

Urinary Phthalate Metabolite Concentrations and Reproductive Outcomes among Women Undergoing in Vitro Fertilization: Results from the EARTH Study

BACKGROUND

Evidence from both animal and human studies suggests that exposure to phthalates may be associated with adverse female reproductive outcomes.

OBJECTIVE

We evaluated the associations between urinary concentrations of phthalate metabolites and outcomes of assisted reproductive technologies (ART).

METHODS

This analysis included 256 women enrolled in the Environment and Reproductive Health (EARTH) prospective cohort study (2004-2012) who provided one to two urine samples per cycle before oocyte retrieval. We measured 11 urinary phthalate metabolites [mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-isobutyl phthalate (MiBP), mono-n-butyl phthalate (MBP), monobenzyl phthalate (MBzP), monoethyl phthalate (MEP), monocarboxyisooctyl phthalate (MCOP), monocarboxyisononyl phthalate (MCNP), and mono(3-carboxypropyl) phthalate (MCPP)]. We used generalized linear mixed models to evaluate the association of urinary phthalate metabolites with in vitro fertilization (IVF) outcomes, accounting for multiple IVF cycles per woman.

RESULTS

In multivariate models, women in the highest as compared with lowest quartile of MEHP, MEHHP, MEOHP, MECPP, ΣDEHP (MEHP + MEHHP + MEOHP + MECPP), and MCNP had lower oocyte yield. Similarly, the number of mature (MII) oocytes retrieved was lower in the highest versus lowest quartile for these same phthalate metabolites. The adjusted differences (95% CI) in proportion of cycles resulting in clinical pregnancy and live birth between women in the fourth versus first quartile of ΣDEHP were -0.19 (-0.29, -0.08) and -0.19 (-0.28, -0.08), respectively, and there was also a lower proportion of cycles resulting in clinical pregnancy and live birth for individual DEHP metabolites.

CONCLUSIONS

Urinary concentrations of DEHP metabolites were inversely associated with oocyte yield, clinical pregnancy, and live birth following ART.

CITATION

Hauser R, Gaskins AJ, Souter I, Smith KW, Dodge LE, Ehrlich S, Meeker JD, Calafat AM, Williams PL, for the EARTH Study Team. 2016. Urinary phthalate metabolite concentrations and reproductive outcomes among women undergoing in vitro fertilization: results from the EARTH study. Environ Health Perspect 124:831-839; http://dx.doi.org/10.1289/ehp.1509760.

Associations of lifetime active and passive smoking with spontaneous abortion, stillbirth and tubal ectopic pregnancy: a cross-sectional analysis of historical data from the Women's Health Initiative

OBJECTIVE

To examine the associations between tobacco exposure and adverse pregnancy outcomes using quantitative measures of lifetime active smoking and secondhand smoke (SHS) exposure.

METHODS

Historical reproductive data on 80 762 women who participated in the Women's Health Initiative Observational Study were examined with a cross-sectional analysis. We assessed self-reported lifetime active and passive tobacco smoke exposure, self-reported spontaneous abortions, stillbirths and ectopic pregnancies.

RESULTS

When compared with never-smoking women, participants who were ever active smokers during their reproductive years had ORs (OR) of 1.16 (95% CI 1.08 to 1.26) for 1 or more spontaneous abortions, 1.44 (95% CI 1.20 to 1.73) for 1 or more stillbirths, and 1.43 (95% CI 1.10 to 1.86) for 1 or more ectopic pregnancies. Never-smoking women participants with the highest levels of lifetime SHS exposure, including childhood >10 years, adult home >20 years and adult work exposure >10 years, when compared with never-smoking women with no SHS exposure had adjusted ORs of 1.17 (95% CI 1.05 to 1.30) for spontaneous abortion, 1.55 (95% CI 1.21 to 1.97) for stillbirth, and 1.61 (95% CI 1.16 to 2.24) for ectopic pregnancy.

CONCLUSIONS

Women who were ever-smokers during their reproductive years had significantly greater estimates of risk for spontaneous abortion, stillbirth and tubal ectopic pregnancy. Never-smoking women with the highest levels of lifetime exposure to SHS had significantly increased estimates of risk for spontaneous abortion, stillbirth and tubal ectopic pregnancy.

Impact of environmental tobacco smoke exposure in women on oxidative stress in the antral follicle and assisted reproduction outcomes

BACKGROUND

Cigarette smoke contains many oxidants and may alter the human reproduction by inducing oxidative stress (OS) in both active and passive smokers. This study was designed to evaluate the effect of environmental tobacco smoke (ETS) exposure on oxidative stress in the follicular fluid and the assisted reproduction outcomes.

MATERIALS AND METHODS

An observational prospective study was carried out on 236 infertile women, who underwent assisted reproduction cycles. The ETS exposure was assessed using self-reported ETS exposure and the cotinine level in follicular fluid. To evaluate the OS in follicular fluid (FF) malon-di-aldehyde (MDA) and total antioxidant capacity (TAC) were measured. The number of retrieved oocytes, rate of metaphase II stage oocytes, fertilization rate, good cleavage rate, and no-fragmented embryo rate were considered as the assisted reproduction outcomes. The results were adjusted for age, body mass index, duration, and etiology of infertility; P-values less than 0.05 were considered significant.

RESULTS

The MDA and TAC levels in FF were not related to the self-report number of the weekly ETS exposure and cotinine levels in FF. Also, the number of retrieved oocytes, MII stage oocytes, fertilization rate, good cleavage rate, and no-fragmented embryo rate were not related to the cotinine level and weekly ETS exposure. However, in women whose cotinine levels in FF were lower and equal/above 3.5 ng/ml, the number of retrieved oocytes was higher (12.63 ± .71 vs. 9.28 ± 1.11, P = 0.01). The relationship between the MDA level and cleavage rate (Beta = -18.5, confidence interval-34.9 and-2.1, P < 0.05) was negatively significant and the relationship between the MII stage rate with TAC (Beta = 0.02, confidence interval 0.01 and 0.04, P < 0.05) was positively significant.

CONCLUSION

The ETS exposure may alter the assisted reproduction success by influencing the number of available oocytes. Although, the OS in a follicular environment affect the ability of oocytes to reach the specific cleavage stages at appropriate time intervals, it does not mediate poor-assisted reproduction outcomes due to ETS exposure.

Cotinine concentrations in follicular fluid as a measure of secondhand tobacco smoke exposure in women undergoing in vitro fertilization: inter-matrix comparisons with urine and temporal variability

We examined the relationship between cotinine measures in follicular fluid (FF) and urine to inform our exposure assessment strategy for an ongoing epidemiological study of secondhand tobacco smoke (STS) exposure and early pregnancy loss. Among subjects undergoing in vitro fertilization (IVF), we compared cotinine levels in paired urine and FF samples from the same women and examined FF cotinine levels over time. We found a weak rank-order relationship (Spearman r<0.2) and poor agreement for classifying nonsmoking individuals as exposed to STS (sensitivity=0.29-0.71; specificity=0.35-0.72) between cotinine concentrations in FF and urine. We observed fair reliability (ICC=0.42-0.52) in FF cotinine concentrations from women undergoing multiple IVF cycles. If available, FF cotinine concentrations may be desired as a biomarker of low-level tobacco smoke exposure over urinary cotinine in studies of early reproduction. Collection of multiple FF samples for cotinine analysis may be needed to accurately represent long-term STS exposure.

Secondhand smoke and adverse fetal outcomes in nonsmoking pregnant women: a meta-analysis

OBJECTIVE

To determine the risk of adverse fetal outcomes of secondhand smoke exposure in nonsmoking pregnant women.

METHODS

This was a systematic review and meta-analysis in accordance with Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. We searched Medline and Embase (to March 2009) and reference lists for eligible studies; no language restrictions were imposed. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were estimated by using random-effect models. Our search was for epidemiologic studies of maternal exposure to secondhand smoke during pregnancy in nonsmoking pregnant women. The main outcome measures were spontaneous abortion, perinatal and neonatal death, stillbirth, and congenital malformations.

RESULTS

We identified 19 studies that assessed the effects of secondhand smoke exposure in nonsmoking pregnant women. We found no evidence of a statistically significant effect of secondhand smoke exposure on the risk of spontaneous abortion (OR: 1.17 [95% CI: 0.88-1.54]; 6 studies). However, secondhand smoke exposure significantly increased the risk of stillbirth (OR: 1.23 [95% CI: 1.09-1.38]; 4 studies) and congenital malformation (OR: 1.13 [95% CI: 1.01-1.26]; 7 studies), although none of the associations with specific congenital abnormalities were individually significant. Secondhand smoke exposure had no significant effect on perinatal or neonatal death.

CONCLUSIONS

Pregnant women who are exposed to secondhand smoke are estimated to be 23% more likely to experience stillbirth and 13% more likely give birth to a child with a congenital malformation. Because the timing and mechanism of this effect is not clear, it is important to prevent secondhand smoke exposure in women before and during pregnancy.

In utero exposure to maternal smoking and women's risk of fetal loss in the Norwegian Mother and Child Cohort (MoBa)

BACKGROUND

Whether in utero exposure to tobacco smoke increases a woman's risk of fetal loss later in life is unknown, though data on childhood exposure suggest an association may exist. This study evaluated the association between in utero exposure to tobacco smoke and fetal loss in the Norwegian Mother and Child Cohort Study (MoBa), which enrolled ∼40% of the pregnant women in Norway from 1999 to 2008.

METHODS

Information on exposure to tobacco smoke in utero, the woman's own smoking behavior during pregnancy and other factors was obtained by a questionnaire completed at ∼17 weeks of gestation. Subsequent late miscarriage (fetal death <20 weeks) and stillbirth (fetal death ≥ 20 weeks) were ascertained from the Norwegian Medical Birth Registry. This analysis included 76 357 pregnancies (MoBa data set version 4.301) delivered by the end of 2008; 59 late miscarriages and 270 stillbirths occurred. Cox proportional hazards models were fit for each outcome and for all fetal deaths combined.

RESULTS

The adjusted hazard ratio (HR) of late miscarriage was 1.23 [95% confidence interval (CI), 0.72-2.12] in women with exposure to maternal tobacco smoke in utero when compared with non-exposed women. The corresponding adjusted HR for stillbirths was 1.11 (95% CI, 0.85-1.44) and for all fetal deaths combined, it was 1.12 (95% CI, 0.89-1.43).

CONCLUSIONS

The relatively wide CI around the HR for miscarriage reflected the limited power to detect an association, due to enrollment around 17 weeks of gestation. However, for in utero exposure to tobacco smoke and risk of stillbirth later in life, where the study power was adequate, our data provided little support for an association.