Associations between lifetime tobacco exposure with infertility and age at natural menopause: the Women's Health Initiative Observational Study

Age at natural menopause and its associated characteristics among Brazilian women: cross-sectional results from ELSI-Brazil

OBJECTIVES

This study aimed to determine the median age at natural menopause and analyze lifestyle, anthropometric, and dietary characteristics associated with the age at natural menopause among Brazilian women.

METHODS

This cross-sectional study involved 2,731 women 50 years and over, drawn from the baseline of the Brazilian Longitudinal Study of Aging (ELSI-Brazil, 2015/16). Nonparametric Kaplan-Meier cumulative survivorship estimates were used to assess the median timing of natural menopause. Cox proportional hazards regression models were employed to estimate the associations between age at natural menopause and exposure variables.

RESULTS

The overall median age at natural menopause was 50 years. In the adjusted Cox model, current smoking (hazard ratio [HR], 1.11; 95% CI, 1.01-1.23) and underweight (HR, 1.34; 95% CI, 1.12-1.61) were associated with earlier natural menopause. Conversely, performing recommended levels of physical activity in the last week (HR, 0.88; 95% CI, 0.80-0.97), being overweight (HR 0.86; 95% CI, 0.74-0.99), and adhering to two or three healthy eating markers (HR, 0.80; 95% CI, 0.66-0.97; HR, 0.76; 95% CI, 0.61-0.94, respectively) were associated with later age at natural menopause. Binge drinking and waist circumference were not associated with age at natural menopause.

CONCLUSIONS

Lifestyle, anthropometric, and dietary characteristics are significant factors that affect the age at natural menopause. Our findings can contribute to public policies targeted at Brazilian women's health.

Cardiovascular disease risk factors and infertility: multivariable analyses and one-sample Mendelian randomization analyses in the Trøndelag Health Study

STUDY QUESTION

Are cardiovascular disease (CVD) risk factors causally associated with higher risk of infertility among women and men?

SUMMARY ANSWER

We found evidence to support a causal relationship between smoking initiation and history of infertility in women.

WHAT IS KNOWN ALREADY

Several CVD risk factors are associated with history of infertility. Previous studies using Mendelian randomization (MR) further support a causal relationship between BMI and infertility in women.

STUDY DESIGN SIZE DURATION

We used data from the Trøndelag Health Study (HUNT) in Norway, a prospective population-based cohort study, including 26 811 women and 15 598 men participating in three survey collections in 1995-1997 (HUNT2), 2006-2008 (HUNT3), and 2017-2019 (HUNT4).

PARTICIPANTS/MATERIALS SETTING METHODS

Our outcome was women's self-reported history of infertility, defined as ever having tried to conceive for 12 months or more or having used ART. We assigned the history of infertility reported by women to their male partners; therefore, the measure of infertility was on the couple level. We used both conventional multivariable analyses and one-sample MR analyses to evaluate the association between female and male CVD risk factors (including BMI, blood pressure, lipid profile measurements, and smoking behaviours) and history of infertility in women and men, separately.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 4702 women (18%) and 2508 men (16%) were classified with a history of infertility. We found a higher risk of infertility among female smokers compared to non-smokers in both multivariable and MR analyses (odds ratio (OR) in multivariable analysis, 1.20; 95% CI, 1.12-1.28; OR in MR analysis, 1.13; CI, 1.02-1.26), and potentially for higher BMI (OR in multivariable analysis, 1.13; CI, 1.09-1.18; OR in MR analysis, 1.11, CI, 0.92-1.34). In multivariable analysis in women, we also found evidence of associations between triglyceride levels, high-density lipoprotein cholesterol, lifetime smoking index, and smoking intensity with higher risk of infertility. However, these results were not consistent in MR analyses. We found no robust or consistent associations between male CVD risk factors and infertility.

LIMITATIONS REASONS FOR CAUTION

Our main limitation was that the CVD risk factors measured might not adequately capture the relevant time periods for when couples were trying to conceive. Additionally, we did not have information on causes of infertility in either women or men.

WIDER IMPLICATIONS OF THE FINDINGS

Women with infertility could have a worse CVD risk factor profile and thus public health interventions aimed at reducing the impact of some CVD risk factors, such as smoking and BMI, could reduce the burden of infertility. However, additional MR studies of the relationship between CVD risk factors and infertility with a larger sample size would be of value.

STUDY FUNDING/COMPETING INTERESTS

The study was supported by a grant from the European Research Council under the European Union's Horizon 2020 research and innovation program (grant agreements no. 947684). This research was also supported by the Research Council of Norway through its Centres of Excellence funding scheme (project no. 262700) and partly funded by the Research Council of Norway, project: Women's fertility-an essential component of health and well-being (project no. 320656). D.A.L. and A.F. work in a unit that is supported by the University of Bristol and the UK Medical Research Council (MC_UU_00011/6). D.A.L.'s contribution to the article is supported by the European Research Council (101021566), the British Heart Foundation (CH/F/20/90003 and AA/18/7/34219). S.B.'s contribution to the article is supported by the Wellcome Trust (225790/Z/22/Z). B.M.B. is funded by The Liaison Committee for education, research and innovation in Central Norway; and the Joint Research Committee between St. Olavs Hospital and the Faculty of Medicine and Health Sciences, NTNU. The genotyping in HUNT was financed by the National Institute of Health (NIH); University of Michigan; The Research Council of Norway; The Liaison Committee for education, research and innovation in Central Norway; and the Joint Research Committee between St. Olavs Hospital and the Faculty of Medicine and Health Sciences, NTNU. None of the funding organizations influenced the study design, reporting, or interpretation of results. The views expressed in the present article are those of the authors and not necessarily any acknowledged funding organization. D.A.L. reports grants from Medtronic Ltd and Roche Diagnostics outside the submitted work. The other authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Tobacco use in currently married pregnant & lactating women in India; key findings from the National Family Health Survey-5

Background

Tobacco use among pregnant and lactating women carries dangerous repercussions for women and their children. Limited information is available at the national level on the prevalence and determinants of tobacco use in this vulnerable sub-population of women. This study aims to estimate the prevalence of tobacco use among currently married pregnant and lactating women and its association with demographic, behavioural and regional determinants in India.

Methods

A cross-sectional study was conducted during which secondary data from the fifth National Family Health Survey, 2019-2020, was analysed. The prevalence and associated 95% confidence intervals (CI) for different forms of tobacco use were documented among currently married pregnant and lactating women. Adjusted Odds Ratio and 95% CI were calculated using multivariate logistic regression to identify the independent factors associated with different forms of tobacco use among respondents after applying sampling weights.

Findings

In India, the prevalence of tobacco use among currently married pregnant and lactating women was 2.5% and 3.2%, respectively, with over 85% of tobacco-using currently married pregnant (85.6%) and lactating (85.6%) women using smokeless tobacco (SLT) only. Age group 30-34 years, working women and the richest wealth quintile were found to be independent predictors of smoked tobacco use among currently married pregnant women. In contrast, among the currently married lactating women, the middle wealth quintile and South Indian region were found to be independent predictors of smoked tobacco use.

Interpretation

Smokeless tobacco was found to be the most prevalent type of tobacco consumed by pregnant and lactating women in India. There is an urgent need to curb tobacco use in this vulnerable sub-population of women in the country by sensitising them to the harmful consequences of tobacco use by integrating tobacco awareness and cessation services during routine ante-natal examinations.

Funding

No funding was received for this study.

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.

Review of mendelian randomization studies on age at natural menopause

Menopause marks the end of the reproductive phase of life. Based on epidemiological studies, abnormal age at natural menopause (ANM) is thought to contribute to a number of adverse outcomes, such as osteoporosis, cardiovascular disease, and cancer. However, the causality of these associations remains unclear. A powerful epidemiological method known as Mendelian randomization (MR) can be used to clarify the causality between ANM and other diseases or traits. The present review describes MR studies that included ANM as an exposure, outcome and mediator. The findings of MR analyses on ANM have revealed that higher body mass index, poor educational level, early age at menarche, early age at first live birth, early age at first sexual intercourse, and autoimmune thyroid disease appear to be involved in early ANM etiology. The etiology of late ANM appears to be influenced by higher free thyroxine 4 and methylene tetrahydrofolate reductase gene mutations. Furthermore, early ANM has been found to be causally associated with an increased risk of osteoporosis, fracture, type 2 diabetes mellitus, glycosylated hemoglobin, and the homeostasis model of insulin resistance level. In addition, late ANM has been found to be causally associated with an increased systolic blood pressure, higher risk of breast cancer, endometrial cancer, endometrioid ovarian carcinoma, lung cancer, longevity, airflow obstruction, and lower risk of Parkinson's disease. ANM is also a mediator for breast cancer caused by birth weight and childhood body size. However, due to the different instrumental variables used, some results of studies are inconsistent. Future studies with more valid genetic variants are needed for traits with discrepancies between MRs or between MR and other types of epidemiological studies.

Exploring the relationship between history of infertility and the experience of menopausal symptoms

OBJECTIVE

The aim of the study is to examine longitudinal associations of history of infertility with menopausal symptoms in midlife.

METHODS

Six hundred ninety-five midlife women (≥45 y old or reporting ≥12 mo of amenorrhea at the midlife visit) in Project Viva, a prospective cohort enrolled 1999-2002 during pregnancy and followed for 18 years after enrollment ("midlife visit"). Exposure was history of infertility defined as time to pregnancy ≥12 months (≥6 mo if ≥35 y), use of medical treatment to conceive, or infertility consultation or treatment in the 6-month preceding enrollment. The primary outcome was score below or above the median on the Menopause Rating Scale (MRS). Secondary outcomes included individual symptom score on the MRS and self-reported age of menopause.

RESULTS

A total of 36.6% had a history of infertility in their lifetime. At the time of MRS completion, the women with prior infertility were older (53.4 [SD, 3.8] vs 51.2 [SD, 3.7] y) than those without infertility and a larger proportion had reached menopause (62% vs 40%). Women with prior infertility were more likely to score above the median on the MRS (Adjusted Odds Ratio [aOR], 1.45; 95% confidence interval [CI], 1.04-2.01) and had higher odds for reporting any depressive mood (aOR, 1.56; 95% CI, 1.12-2.16) and irritability (aOR, 1.57; 95% CI, 1.13-2.19). There was a trend toward greater severity of sleep problems among women with prior infertility. There was no association of prior infertility with report of other menopausal symptoms or age of menopause.

CONCLUSIONS

Our findings suggest that women with prior infertility are more likely to have an MRS score above the median and experience depressive mood, irritability, and sleep problems during midlife than women without infertility. These findings have implications for mental health screening among midlife women.

Study on depletion of ovarian function and late-life chronic diseases in India

OBJECTIVE

The current study aims to understand premature and early menopausal age in association with chronic conditions.

METHODS

The present cross-sectional study analyzed nationally representative data from LASI (Longitudinal Aging Study in India) from 2017 to 2018. Bivariate analysis including cross-tabulation and χ2 tests were performed. Further multiple regression analysis was performed, using the generalized linear model of logit link.

RESULTS

Approximately 2533 (8%) older women reported that they had experienced premature menopause (before age 40), while 3889 (12.4%) reported having early menopause (age 40-44). The likelihood of a woman with premature menopause developing cardiovascular diseases (CVDs) is 15% higher (adjusted odds ratio [AOR], 1.15; P < 0.05) than those who do not experience premature menopause, while women with early menopause have a 13% higher risk (AOR, 1.13; P < 0.05). For women who experienced premature menopause and were also smokers, the probability of developing CVDs was higher. Other chronic diseases such as bone or joint problems, diabetes, and eye vision problems were also shown to be significant health problems among women who had premature ovarian failure.

CONCLUSION

Our results show significant association between women with premature or early depletion of ovarian function and chronic health conditions such as cardiovascular diseases, bone or joint problems, vision problems, and neurological or psychiatric disorders at their later life ages. Comprehensive strategies in the form of lifestyle changes may regulate hormonal levels and allow the body to reach menopause at the appropriate age.

Linkage of premature and early menopause with psychosocial well-being: a moderated multiple mediation approach

PURPOSE

Menopause occurring before the age of 40 is premature and between 40 and 44 years age is early, since the natural age of menopause lies between 45 and 50. The endocrine changes that come with menopause include an erratic decline in estrogen levels which affects the brain. Thus, leading to changes in cognitive function in the longer term due to the menopausal transition. The study aims to explore the effect of premature and early menopause on cognitive health, and psychosocial well-being. The moderated multiple mediation hypothesis of the study is that the effect of premature or early menopause is mediated by depression and insomnia, while all the pathways are moderated by smoking habits.

DATA AND METHODS

The study utilized Longitudinal Aging Study in India (LASI), 2017-2018, Wave 1 data. The sample of 31,435 women were aged 45 and above and did not undergo hysterectomy. A moderated multiple mediation model was used to understand the association between premature or early menopause (X), insomnia (M1), depression (M2), moderator (W), and cognitive health (Y), while controlling for possible confounders.

RESULTS

Premature menopause was negatively associated with cognition (β:-0.33; SE:0.12; p < 0.05), whereas positively associated with insomnia (β:0.18; SE:0.03; p < 0.001) and depression (β:0.25; SE:0.04; p < 0.001). There is a moderating effect of smoking or tobacco consumption has a significant moderating effect on the pathways among premature menopause, depression, insomnia and cognition. When the same model was carried out for early menopause (40-44 years), the results were not significant.

CONCLUSIONS

The findings emphasize the fact that smoking is associated with premature menopause, depression and insomnia. Women who experienced premature menopause has lower cognitive scores, depressive symptoms and insomnia symptoms, which were higher among those who consumed tobacco. The study, strongly recommends the dissemination of information on the negative effects of tobacco consumption and making more informed choices to maintain a healthy life. More research into various methods and therapy is needed to determine the relationship between the age of early menopause and their psychosocial well-being.

Association of earlier age at menopause with risk of incident dementia, brain structural indices and the potential mediators: a prospective community-based cohort study

Background

To date, there is no homogeneous evidence of whether earlier age at menopause is associated with incident dementia. In addition, the underlying mechanism and driven mediators are largely unknown. We aimed to fill these knowledge gaps.

Methods

This community-based cohort study included 154,549 postmenopausal women without dementia at enrolment (between 2006 and 2010) from the UK Biobank who were followed up until June 2021. We followed up until June 2021. Age at menopause was entered as a categorical variable (<40, 40-49, and ≥50 years) with ≥50 years taken as a reference. The primary outcome was all-cause dementia in a time-to-event analysis and the secondary outcomes included Alzheimer's disease, vascular dementia, and other types of dementia. In addition, we investigated the association between magnetic resonance (MR) brain structure indices with earlier menopause, and explored the potential underlying driven mediators on the relationship between earlier menopause and dementia.

Findings

2266 (1.47%) dementia cases were observed over a median follow-up period of 12.3 years. After adjusting for confounders, women with earlier menopause showed a higher risk of all-cause dementia compared with those ≥50 years (adjusted-HRs [95% CIs]: 1.21 [1.09-1.34] and 1.71 [1.38-2.11] in the 40-49 years and <40 years groups, respectively; P for trend <0.001). No significant interactions between earlier menopause and polygenic risk score, cardiometabolic factors, type of menopause, or hormone-replacement therapy strata were found. Earlier menopause was negatively associated with brain MR global and regional grey matter indices, and positively associated with white matter hyperintensity. The relationship between earlier menopause and dementia was partially mediated by menopause-related comorbidities including sleep disturbance, mental health disorder, frailty, chronic pain, and metabolic syndrome, with the proportion (95% CI) of mediation effect being 3.35% (2.18-5.40), 1.38% (1.05-3.20), 5.23% (3.12-7.83), 3.64% (2.88-5.62) and 3.01% (2.29-4.40), respectively. Multiple mediator analysis showed a combined effect being 13.21% (11.11-18.20).

Interpretation

Earlier age at menopause was associated with risk of incident dementia and deteriorating brain health. Further studies are warranted to clarify the underlying mechanisms by which earlier age at menopause is linked to an increased risk of dementia, and to determine public health strategies to attenuate this association.

Funding

National Natural Science Foundation of China, the Science and Technology Program of Guangzhou, the Key Area Research and Development Program of Guangdong Province, the China Postdoctoral Science Foundation, and the Guangdong Basic and Applied Basic Research Foundation.

Associations between smoking status and infertility: a cross-sectional analysis among USA women aged 18-45 years

Background

Although many studies have proven the harmful effects of smoking on human health, the associations between smoking status and infertility are limited in large epidemiologic studies. We aimed to investigate the associations between smoking status and infertility among child-bearing women in the United States of America (USA).

Methods

A total of 3,665 female participants (aged 18-45) from the National Health and Nutrition Examination Survey (NHANES) (2013-2018) were included in this analysis. All data were survey-weighted, and corresponding logistic regression models were performed to investigate the associations between smoking status and infertility.

Results

In a fully adjusted model, the risk of infertility was found to be increased by 41.8% among current smokers compared to never smokers (95% CI: 1.044-1.926, P=0.025). In the subgroup analysis, the odds ratios (95% CI) of the risk of infertility for current smokers were 2.352 (1.018-5.435) in the unadjusted model for Mexican American, 3.675 (1.531-8.820) in the unadjusted model but 2.162 (0.946-4.942) in fully adjusted model for people aged 25-31, 2.201 (1.097-4.418) in the unadjusted model but 0.837 (0.435-1.612) in fully adjusted model for people aged 32-38.

Conclusion

Current smokers was associated with a higher risk of infertility. The underlying mechanism of these correlations still needs more research. Our findings indicated that quitting smoking may serve as a simple index to reduce the risk of infertility.

The causal association between smoking initiation, alcohol and coffee consumption, and women's reproductive health: A two-sample Mendelian randomization analysis

Objective: A number of epidemiological studies have demonstrated that smoking initiation and alcohol and coffee consumption were closely related to women's reproductive health. However, there was still insufficient evidence supporting their direct causality effect. Methods: We utilized two-sample Mendelian randomization (TSMR) analysis with summary datasets from genome-wide association study (GWAS) to investigate the causal relationship between smoking initiation, alcohol and coffee consumption, and women's reproductive health-related traits. Exposure genetic instruments were used as variants significantly related to traits. The inverse-variance weighted (IVW) method was used as the main analysis approach, and we also performed MR-PRESSO, MR-Egger, weighted median, and weighted mode to supplement the sensitivity test. Then, the horizontal pleiotropy was detected by using MRE intercept and MR-PRESSO methods, and the heterogeneity was assessed using Cochran's Q statistics. Results: We found evidence that smoking women showed a significant inverse causal association with the sex hormone-binding globulin (SHBG) levels (corrected β = -0.033, p = 9.05E-06) and age at menopause (corrected β = -0.477, p = 6.60E-09) and a potential positive correlation with the total testosterone (TT) levels (corrected β = 0.033, p = 1.01E-02). In addition, there was suggestive evidence for the alcohol drinking effect on the elevated TT levels (corrected β = 0.117, p = 5.93E-03) and earlier age at menopause (corrected β = -0.502, p = 4.14E-02) among women, while coffee consumption might decrease the female SHBG levels (corrected β = -0.034, p = 1.33E-03). Conclusion: Our findings suggested that smoking in women significantly decreased their SHBG concentration, promoted earlier menopause, and possibly reduced the TT levels. Alcohol drinking had a potential effect on female higher TT levels and earlier menopause, while coffee consumption might lead to lower female SHBG levels.

Association of Premature Menopause With Risk of Abdominal Aortic Aneurysm in the Women's Health Initiative

OBJECTIVE

To determine if premature menopause and early menarche are associated with increased risk of AAA, and to explore potential effect modification by smoking history.

SUMMARY OF BACKGROUND DATA

Despite worse outcomes for women with AAA, no studies have prospectively examined sex-specific risk factors, such as premature menopause and early menarche, with risk of AAA in a large, ethnically diverse cohort of women.

METHODS

This was a post-hoc analysis of Women's Health Initiative participants who were beneficiaries of Medicare Parts A&B fee-for-service. AAA cases and interventions were identified from claims data. Follow-up period included Medicare coverage until death, end of follow-up or end of coverage inclusive of 2017.

RESULTS

Of 101,119 participants included in the analysis, the mean age was 63 years and median follow-up was 11.3 years. Just under 10,000 (9.4%) women experienced premature menopause and 22,240 (22%) experienced early men-arche. Women with premature menopause were more likely to be overweight, Black, have >20 pack years of smoking, history of cardiovascular disease, hypertension, and early menarche. During 1,091,840 person-years of follow-up, 1125 women were diagnosed with AAA, 134 had premature menopause (11.9%), 93 underwent surgical intervention and 45 (48%) required intervention for ruptured AAA. Premature menopause was associated with increased risk of AAA [hazard ratio 1.37 (1.14, 1.66)], but the association was no longer significant after multivariable adjustment for demographics and cardiovascular disease risk factors. Amongst women with ≥20 pack year smoking history (n = 19,286), 2148 (11.1%) had premature menopause, which was associated with greater risk of AAA in all models [hazard ratio 1.63 (1.24, 2.23)]. Early menarche was not associated with increased risk of AAA.

CONCLUSIONS

This study finds that premature menopause may be an important risk factor for AAA in women with significant smoking history. There was no significant association between premature menopause and risk of AAA amongst women who have never smoked. These results suggest an opportunity to develop strategies for better screening, risk reduction and stratification, and outcome improvement in the comprehensive vascular care of women.

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.

Smoking and infertility: multivariable regression and Mendelian randomization analyses in the Norwegian Mother, Father and Child Cohort Study

OBJECTIVE

To investigate the association between smoking and infertility.

DESIGN

Prospective study.

SETTING

Nationwide cohort.

PATIENTS

28,606 women and 27,096 men with questionnaire and genotype information from the Norwegian Mother, Father, and Child Cohort Study.

INTERVENTION

Self-reported information on smoking (having ever smoked [both sexes], age at initiation [women only], cessation [women only], and cigarettes/week in current smokers [both sexes]) was gathered. Genetically predetermined levels or likelihood of presenting these traits were estimated for Mendelian randomization.

MAIN OUTCOME MEASURE

Infertility (time-to-pregnancy ≥12 months).

RESULTS

Having ever smoked was unrelated to infertility in women or men. Higher smoking intensity in women was associated with greater infertility odds (+1 standard deviation [SD, 48 cigarettes/week]: odds ratio [OR]crude, 1.19; 95% confidence interval [CI] 1.11-1.28; ORadjusted 1.12; 95% CI, 1.03-1.21), also after adjusting for the partner's tobacco use. Later smoking initiation (+1 SD [3.2 years]: ORcrude, 0.94; 95% CI, 0.88-0.99; ORadjusted 0.89; 95% CI, 0.84-0.95) and smoking cessation (vs. not quitting: ORcrude, 0.83; 95% CI, 0.75-0.91; ORadjusted, 0.83; 95% CI, 0.75-0.93) were linked to decreased infertility in women. Nevertheless, Mendelian randomization results were not directionally consistent for smoking intensity and cessation and were estimated imprecisely in the 2-sample approach. In men, greater smoking intensity was not robustly associated with infertility in multivariable regression and Mendelian randomization.

CONCLUSIONS

We did not find robust evidence of an effect of smoking on infertility. This may be due to a true lack of effect, weak genetic instruments, or other kinds of confounding.

Association of weight, smoking, and alcohol consumption with age at natural menopause

In South Korea, rapid economic growth and modernization have led to changes in lifestyle factors that may affect age at natural menopause. Data from 4,793 women aged ≥55 years, who had a natural menopause, were analyzed from the Korea National Health and Nutrition Examination Survey (2013-2017). Multinomial logistic regression was used to examine the association between lifestyle factors and age at natural menopause after adjusting for birth cohort (Model 1) and sociodemographic and reproductive factors (Model 2). Overall, 3.1% of women experienced premature menopause (<40 years), 7.6% early menopause (40-44 years), and 12.8% late menopause (≥55 years). Women born in the 1940s or earlier among the birth cohorts had the highest prevalence of premature (70.0%), early (58.5%), and late (43.1%) menopause. In Model 2, current smoking (odds ratio = 3.99 and 95% confidence interval = 1.35-11.81) was associated with premature menopause. Low (<18.5 kg/m²) and high (≥25 kg/m²) body mass index were associated with early (odds ratio = 2.30 and 95% confidence interval = 1.01-5.22) and late (odds ratio = 1.38 and 95% confidence interval = 1.10-1.72) menopause respectively. Conversely, there was no association between age at natural menopause and alcohol consumption. The results suggest that healthy lifestyle factors, such as not smoking and proper weight maintenance, are significant factors affecting age at natural menopause. Our findings may help develop health policies and provide targeted care to improve women's health after midlife.

The Effects of Environmental Contaminant Exposure on Reproductive Aging and the Menopause Transition

PURPOSE OF REVIEW

Menopause marks the end of a woman's reproductive lifetime. On average, natural menopause occurs at 51 years of age. However, some women report an earlier age of menopause than the national average. This can be problematic for women who delay starting a family. Moreover, early onset of menopause is associated with increased risk of cardiovascular disease, depression, osteoporosis, and premature death. This review investigates associations between exposure to endocrine-disrupting chemicals (EDCs) and earlier onset of menopause.

RECENT FINDINGS

Recent data suggest exposure to certain EDCs may accelerate reproductive aging and contribute to earlier onset of menopause. Human and rodent-based studies identify positive associations between exposure to certain EDCs/environmental contaminants and reproductive aging, earlier onset of menopause, and occurrence of vasomotor symptoms. These findings increase our understanding of the detrimental effects of EDCs on female reproduction and will help lead to the development of strategies for the treatment/prevention of EDC-induced reproductive aging.

Factors related to age at natural menopause in China: results from the China Kadoorie Biobank

OBJECTIVES

The aim of this study was to investigate the potentially modifiable factors affecting age at natural menopause (ANM) in Chinese women.

METHODS

We used cross-sectional data from the China Kadoorie Biobank study which that recruited 0.5 million (0.3 million women) Chinese adults aged 30 to 79 from 2004 to 2008. Multinomial logistic regression models were used to examine the relationships between ANM and various factors recorded at baseline.

RESULTS

Among 87,349 postmenopausal women, the mean ANM (SD) was 48.7 (4.3) years. Older age, being a housewife, earlier menarche, and passive smoking were associated with both premature menopause (PM, ie, ANM <40 years) and early menopause (EM, ie, ANM between 40 and 44 years). A higher odds for EM was observed in women who were widowed (odds ratio: 1.10, 95% confidence interval: 1.04-1.16), had spontaneous abortions (1.33 [1.05-1.69]), current regular smoking (1.19 [1.07-1.37]), and frequent spicy food intake (1.11 [1.05-1.08]). Higher socioeconomic status; later first birth; more live births and induced abortions; longer breastfeeding; tea drinking, as well as intakes of meat, fruits, dairy, and soybean products; and increased body mass index gain were inversely associated with PM and/or EM. In contrast, women who had more pregnancies, occasional alcohol drinking, higher levels of physical activity or body mass index, vitamin intake, and hypertension were more likely to have a later age at menopause (LM, ie, ANM ≥53 years).

CONCLUSIONS

This large epidemiological study found a wide range of sociodemographic, lifestyle, dietary, and reproductive factors related to PM, EM, and LM in Chinese women.

Preconception lifestyle advice for people with infertility

BACKGROUND

Infertility is a prevalent problem that has significant consequences for individuals, families, and the community. Modifiable lifestyle factors may affect the chance of people with infertility having a baby. However, no guideline is available about what preconception advice should be offered. It is important to determine what preconception advice should be given to people with infertility and to evaluate whether this advice helps them make positive behavioural changes to improve their lifestyle and their chances of conceiving.

OBJECTIVES

To assess the safety and effectiveness of preconception lifestyle advice on fertility outcomes and lifestyle behavioural changes for people with infertility.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, CENTRAL, MEDLINE, Embase, PsycINFO, AMED, CINAHL, trial registers, Google Scholar, and Epistemonikos in January 2021; we checked references and contacted field experts to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), randomised cross-over studies, and cluster-randomised studies that compared at least one form of preconception lifestyle advice with routine care or attention control for people with infertility.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Primary effectiveness outcomes were live birth and ongoing pregnancy. Primary safety outcomes were adverse events and miscarriage. Secondary outcomes included reported behavioural changes in lifestyle, birth weight, gestational age, clinical pregnancy, time to pregnancy, quality of life, and male factor infertility outcomes. We assessed the overall quality of evidence using GRADE criteria.

MAIN RESULTS

We included in the review seven RCTs involving 2130 participants. Only one RCT included male partners. Three studies compared preconception lifestyle advice on a combination of topics with routine care or attention control. Four studies compared preconception lifestyle advice on one topic (weight, alcohol intake, or smoking) with routine care for women with infertility and specific lifestyle characteristics. The evidence was of low to very low-quality. The main limitations of the included studies were serious risk of bias due to lack of blinding, serious imprecision, and poor reporting of outcome measures. Preconception lifestyle advice on a combination of topics versus routine care or attention control Preconception lifestyle advice on a combination of topics may result in little to no difference in the number of live births (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.79 to 1.10; 1 RCT, 626 participants), but the quality of evidence was low. No studies reported on adverse events or miscarriage. Due to very low-quality evidence, we are uncertain whether preconception lifestyle advice on a combination of topics affects lifestyle behavioural changes: body mass index (BMI) (mean difference (MD) -1.06 kg/m², 95% CI -2.33 to 0.21; 1 RCT, 180 participants), vegetable intake (MD 12.50 grams/d, 95% CI -8.43 to 33.43; 1 RCT, 264 participants), alcohol abstinence in men (RR 1.08, 95% CI 0.74 to 1.58; 1 RCT, 210 participants), or smoking cessation in men (RR 1.01, 95% CI 0.91 to 1.12; 1 RCT, 212 participants). Preconception lifestyle advice on a combination of topics may result in little to no difference in the number of women with adequate folic acid supplement use (RR 0.98, 95% CI 0.95 to 1.01; 2 RCTs, 850 participants; I² = 4%), alcohol abstinence (RR 1.07, 95% CI 0.99 to 1.17; 1 RCT, 607 participants), and smoking cessation (RR 1.01, 95% CI 0.98 to 1.04; 1 RCT, 606 participants), on low quality evidence. No studies reported on other behavioural changes. Preconception lifestyle advice on weight versus routine care Studies on preconception lifestyle advice on weight were identified only in women with infertility and obesity. Compared to routine care, we are uncertain whether preconception lifestyle advice on weight affects the number of live births (RR 0.94, 95% CI 0.62 to 1.43; 2 RCTs, 707 participants; I² = 68%; very low-quality evidence), adverse events including gestational diabetes (RR 0.78, 95% CI 0.48 to 1.26; 1 RCT, 317 participants; very low-quality evidence), hypertension (RR 1.07, 95% CI 0.66 to 1.75; 1 RCT, 317 participants; very low-quality evidence), or miscarriage (RR 1.50, 95% CI 0.95 to 2.37; 1 RCT, 577 participants; very low-quality evidence). Regarding lifestyle behavioural changes for women with infertility and obesity, preconception lifestyle advice on weight may slightly reduce BMI (MD -1.30 kg/m², 95% CI -1.58 to -1.02; 1 RCT, 574 participants; low-quality evidence). Due to very low-quality evidence, we are uncertain whether preconception lifestyle advice affects the percentage of weight loss, vegetable and fruit intake, alcohol abstinence, or physical activity. No studies reported on other behavioural changes. Preconception lifestyle advice on alcohol intake versus routine care Studies on preconception lifestyle advice on alcohol intake were identified only in at-risk drinking women with infertility. We are uncertain whether preconception lifestyle advice on alcohol intake affects the number of live births (RR 1.15, 95% CI 0.53 to 2.50; 1 RCT, 37 participants; very low-quality evidence) or miscarriages (RR 1.31, 95% CI 0.21 to 8.34; 1 RCT, 37 participants; very low-quality evidence). One study reported on behavioural changes for alcohol consumption but not as defined in the review methods. No studies reported on adverse events or other behavioural changes. Preconception lifestyle advice on smoking versus routine care Studies on preconception lifestyle advice on smoking were identified only in smoking women with infertility. No studies reported on live birth, ongoing pregnancy, adverse events, or miscarriage. One study reported on behavioural changes for smoking but not as defined in the review methods.

AUTHORS' CONCLUSIONS

Low-quality evidence suggests that preconception lifestyle advice on a combination of topics may result in little to no difference in the number of live births. Evidence was insufficient to allow conclusions on the effects of preconception lifestyle advice on adverse events and miscarriage and on safety, as no studies were found that looked at these outcomes, or the studies were of very low quality. This review does not provide clear guidance for clinical practice in this area. However, it does highlight the need for high-quality RCTs to investigate preconception lifestyle advice on a combination of topics and to assess relevant effectiveness and safety outcomes in men and women with infertility.

Effects of Environment and Lifestyle Factors on Premature Ovarian Failure

Premature ovarian insufficiency (POI) or primary ovarian failure is defined as a cessation of the menstrual cycle in women younger than 40 years old. It is strictly defined as more than 4 months of oligomenorrhea or amenorrhea in a woman <40 years old, associated with at least two follicle-stimulating hormone (FSH) levels >25 U/L in the menopausal range, detected more than 4 weeks apart. It is estimated that POI was affected 1 and 2% of women. Although 80% of POI cases are of unknown etiology, it is suggested that genetic disorder, autoimmune origin, toxins, and environmental factors, as well as personal lifestyles, may be risk factors of developing POI. In this section, we will discuss the influences of environmental and lifestyle factors on POI. Moreover updated basic research findings regarding how these environmental factors affect female ovarian function via epigenetic regulations will also be discussed.

Toenail metal concentrations and age at menopause: A prospective study

BACKGROUND

Menopause timing is related to cancer, cardiovascular disease, and mortality. Lead has been associated with an earlier age at menopause, but no study has considered exposure to other metals or multiple metals simultaneously.

METHODS

At baseline, we measured toenail concentrations of 16 metals for 903 premenopausal women in the Sister Study (2003-2009). Age at menopause was ascertained through follow-up questionnaires. Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between individual metals and age at menopause. We used quantile-g-computation to examine the association between age at menopause and the joint effect of a simultaneous increase in (1) all metals and for subgroups of metals categorized as (2) essential or (3) non-essential.

RESULTS

For individual metals, we observed negligible associations except for an interquartile range increase in lead which was modestly associated with an earlier age at menopause (HR = 1.03, 95% CI = 1.01, 1.05). In the mixture analyses, a quartile increase in all metals was associated with a later age at menopause (HR = 0.81, 95% CI = 0.64, 1.02). The metals with the largest negative contributions (i.e., associated with a later age at menopause) were chromium and nickel. The joint effect for the essential metals remained inverse (HR = 0.83, 95% CI = 0.64, 1.07), but was attenuated for nonessential metals (HR = 0.98, 95% CI = 0.76, 1.24).

CONCLUSIONS

Although no individual metal was strongly associated with age at menopause, our joint effect analysis suggests that having low levels of essential metals could be associated with an earlier age at menopause.

Taking fertility for granted - a qualitative exploration of fertility awareness among young, childless men in Denmark and Sweden

Most previous studies about fertility knowledge and attitudes among men have been based on quantitative methods using questionnaires with fixed-choice response options. The aims of this qualitative study were to explore childless young men's reflections on fertility and infertility through semi-structured interviews. Danish (n = 17) and Swedish (n = 12) young childless men aged between 20 and 30 years in their last year of education were interviewed. Data were analysed using qualitative content analysis. Few informants had considered their own fertility, and most were positive towards fertility treatment. The young men had inadequate knowledge about factors that can potentially impair male and female fertility. On average, the young men each mentioned three different factors they believed influence male and female fertility: (i) health behaviour; (ii) factors beyond personal control; and (iii) age. None mentioned sexual transmitted infections (STIs) but most appeared aware of the effect of increasing age on fertility. The results of this study highlight the need for educational strategies to improve young men's knowledge about fertility and the factors that influence it, particularly about the potential adverse effect of STIs on fertility.

Risk profile of Qatari women treated for infertility in a tertiary hospital: a case-control study

BACKGROUND

Female infertility is a multifactorial condition constituting a worldwide public health problem. The ability to reproduce is an important product of any marriage, hence infertility may exert a negative impact on physical, financial, social and emotional wellbeing of affected couples. The cornerstone to the management of any disease, including infertility, is prevention. Identifying the modifiable risk factors of female infertility will aid at prevention, early detection, and treatment of medical conditions that can threaten fertility as well as promoting healthy behaviours that can preserve it.

AIM

To explore the risk profile of infertility among Qatari women and compare risk factors distribution among primary vs. secondary infertility.

METHODOLOGY

A hospital-based case control study was conducted from September 17th, 2017- February 10th, 2018. Cases (n = 136) were enrolled from infertility clinic and controls (pregnant women, n = 272), were enrolled from antenatal clinic, Women Hospital, Hamad Medical Corporation (HMC). Interview questionnaire was utilized to collect data about sociodemographic, risk factors related to infertility and patient health Questionnaire (PHQ)-2. Body Mass Index (BMI) was calculated. Logistic regression was used to identify the associated factors to infertility. Statistical significance was set at 0.05.

RESULTS

Forty three primary and ninety three secondary infertility cases were included. Risk factors were age >  35 years (OR = 3.7, 95% CI: 1.41-9.83), second-hand smoking (OR = 2.44, 95% CI:1.26-4.73), steady weight gain (OR = 4.65,, 95% CI: 2.43-8.91), recent weight gain (OR = 4.87, 95% CI: 2.54-9.32), menstrual cycle irregularities (OR = 4.20, 95% CI:1.14-15.49), fallopian tube blockage (OR = 5.45, 95% CI: 1.75-16.95), and symptoms suggestive of sexually transmitted infections (STIs) including chronic lower abdominal/pelvic pain (OR = 3.46, 95% CI: 1.57-7.63), abnormal vaginal discharge (OR = 3.32, 95% CI:1.22-9.03) and dyspareunia (OR = 7.04, 95% CI: 2.76-17.95). Predictive factors for secondary infertility were; longer time from previous conception (OR = 5.8, 95% CI: 3.28-10.21), history of stillbirth (OR = 2.63, 95% CI: 1.04-6.67) or miscarriage (OR = 2.11, 95% CI: 1.21-3.68) and postpartum infection (OR = 3.75, 95% CI: 1.27-11.06). Protective factors were higher education level (OR = 0.44, 95% CI: 0.25-0.78), higher income (OR = 0.17, 95% CI: 0.06-0.49), and awareness/loyalty to fertility window (OR = 0.33, 95% CI: 0.21-0.52 and OR = 0.29, 95% CI: 0.19-0.44, consequently).

CONCLUSION

This study highlighted the opportunities to strengthen public health as well as hospital-based health promotion programs importantly toward behavioural-related risk factors (e.g. smoking, obesity, STIs etc.). Moreover, detecting, preventing, and managing modifiable risk factors through awareness, screening and early management of chronic diseases, may contribute at reduction of incidence and severity of infertility. Such interventions can be delivered at premarital, family planning, post-natal and antenatal clinics at primary health care with early referral to secondary care if required.

Mapping premature ovarian insufficiency and potential environmental factors: A tool for triggering in-depth research of the problem in Slovenia

Aiming at triggering in-depth research of the problem of Premature Ovarian Insufficiency (POI) in Slovenia, we assessed the regional differences in POI incidence emphasising the relationship with social and physical environmental factors at the population level using a mapping approach. The differences in POI incidence between regions were tested by goodness-of-fit chi-square test, while Pearson correlation coefficient was used to assess the ecological relationship between POI incidence and selected environmental indicators. Significant indicators were mapped. The results showed highly significant interregional differences in POI incidence (p<0.001). Statistically significant ecological relationships were observed between POI incidence and prevalence of active smoking (p=0.001), passive smoking (p=0.017) and consumption of vitamins (p=0.008). The results could be used in diminishing interregional differences in POI. It was concluded that mapping is an effective tool in public health research, especially in triggering new activities.

An Appraisal of the Role of Previously Reported Risk Factors in the Age at Menopause Using Mendelian Randomization

Objective

Menopause at a young age is associated with many health problems in women, including osteoporosis, depressive symptoms, coronary disease, and stroke. Many traditional observational studies have reported some potential risk factors for early menopause but have drawn different conclusions. This inconsistency can be attributed mainly to unmodified confounding factors. Identifying the factors causally associated with age at menopause is important for early intervention in women with abnormal menopause timing, and for improving the quality of life for postmenopausal women. This study aims to appraise whether the previously reported risk factors are causally associated with early age at natural menopause (ANM) susceptibility.

Methods

We used Mendelian randomization, a statistical method wherein genetic variants are used to determine whether an observational association between a risk factor and an outcome is consistent with a causal effect.

Results

Women with earlier age at menarche (β = 0.34, se = 0.16, p = 0.035), lower education level (β = 1.19, se = 0.41, p = 0.004) and higher body mass index (β = −0.05, se = 0.02, p = 0.027) had greater risk for early ANM. The causal link between early age at menarche and early ANM was replicated using ReproGen consortium data (β = 0.23, se = 0.07, p = 0.001). However, a current smoking habit, one of previously reported risk factors, was less likely to be correlated causally with early ANM, suggesting that previous observational studies may not have sufficiently adjusted for confounders.

Conclusion

Our results help to identify the risk factors of ANM via a genetics approach and future research into the biological mechanism could further help with targeted prevention for early menopause.

Factors associated with age at natural menopause among elderly women in São Paulo, Brazil

OBJECTIVES

To analyze factors associated with age at natural menopause in elderly women who are part of the Health, Well-Being and Aging Study- which is a representative sample of elderly residents of the municipality of São Paulo, Brazil.

METHODS

Multivariate Cox proportional-hazards analysis using data from a total of 1,415 women with natural menopause. We included 163 women with hysterectomy, oophorectomy, and estrogen therapy as censored data.

RESULTS

The median age of natural menopause was 50 years. In the multivariate Cox proportional hazards, smoking was associated with earlier age at natural menopause for the three cohorts (2000, 2006, and 2010). Current smokers had a 35% higher risk of earlier natural menopause (hazard ratio [HR] 1.35, 95% confidence interval [CI] 1.12, 1.62) and former smokers had a 27% higher risk of earlier natural menopause (HR 1.27, 95% CI 1.09, 1.50), in comparison with never-smokers. Women with 8 years or more of formal education had a 33% lower risk of earlier natural menopause (HR 0.67, 95% CI 0.50, 0.89) than women with no education, and women who were separated, widowed, or divorced had a 15% higher risk of earlier natural menopause (HR 1.15, 95% CI 1.00, 1.31) in comparison with married women. Marital status and parity were associated with later age at natural menopause only in 2006.

CONCLUSIONS

We found significant associations of age at natural menopause with reproductive and lifestyle factors similar to some studies of women from developed countries.

Illicit drug use and fertility treatment: should we be developing a standard operating procedure?

At present, there are no reliable data to identify the number of patients who present for infertility investigations and who are current users of illicit drugs. Therefore, the full extent of this problem remains hidden. Estimates can be made on the basis of population use, although this lacks rigour. The use of illicit drugs can impact on infertility investigations, treatment, welfare of the child and parenting. Furthermore, it can result in serious legal sanctions, including imprisonment. There does not appear to be consistent practice across HFEA licenced clinics in either requiring: (i) the addicted patient to have a specified drug-free period before commencing investigations; or (ii) all patients to be routinely screened. As well as describing the extent of illicit drug use in the UK population, and therefore in those who present in clinic, this paper will discuss screening and encourages debate across clinics regarding a mandatory drug-free period and the development of an appropriate Standard Operating Procedure.

Towards Prepared mums (TOP-mums) for a healthy start, a lifestyle intervention for women with overweight and a child wish: study protocol for a randomised controlled trial in the Netherlands

INTRODUCTION

Periconception obesity is associated with a higher risk for adverse perinatal outcomes such as gestational diabetes mellitus, preeclampsia, large for gestational age, operative delivery and preterm birth. Lifestyle interventions during pregnancy have resulted in insufficient effects on reducing these perinatal complications. A few reasons for this disappointing effect can be suggested: (1) the time period during pregnancy for improvement of developmental circumstances is too short; (2) the periconception period in which complications originate is not included; and (3) lifestyle interventions may not have been sufficiently multidisciplinary and customised. A preconception lifestyle intervention might be more effective to reduce perinatal complications. Therefore, the aim of the Towards Prepared mums study is to evaluate the effect of a lifestyle intervention starting prior to conception on lifestyle behaviour change.

METHODS AND ANALYSIS

This protocol outlines a non-blinded, randomised controlled trial. One hundred and twelve women (18-40 years of age) with overweight or obesity (body mass index≥25.0 kg/m2) who plan to conceive within 1 year will be randomised to either the intervention or care as usual group. The intervention group will receive a multidisciplinary, customised lifestyle intervention stimulating physical activity, a healthy diet and smoking cessation, if applicable. The lifestyle intervention and monitoring will take place until 12 months postpartum. The primary outcome is difference in weight in kg from baseline to 6 weeks postpartum. Secondary outcomes are gestational weight gain, postpartum weight retention, smoking cessation, dietary and physical activity habits. Furthermore, exploratory outcomes include body composition, cardiometabolic alterations, time to pregnancy, need for assisted reproductive technologies, perinatal complications of mother and child, and lung function of the child. Vaginal and oral swabs, samples of faeces, breast milk, placenta and cord blood will be stored for evaluation of microbial flora, epigenetic markers and breast milk composition. Furthermore, a cost-effectiveness analysis will take place.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Medical Ethical Committee of Maastricht University Medical Centre+ (NL52452.068.15/METC152026). Knowledge derived from this study will be made available by publications in international peer-reviewed scientific journals and will be presented at (inter)national scientific conferences. A dissemination plan for regional and national implementation of the intervention is developed.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT02703753.

Association of African-American ethnicity and smoking status with total and individual damage index in systemic lupus erythematosus

INTRODUCTION

Smoking has been associated with increased incidence, severity of cutaneous lupus, and lupus activity. We looked at the association of both smoking and ethnicity with the individual damage items from the SLICC/ACR Damage Index.

METHODS

Poisson regression was used to model the total SLICC/ACR Damage Index score against ever smoking. Cox regression was used to assess the relationship between time to individual damage items and ever smoking. Furthermore, we compared SLICC/ACR Damage Index items among African-American and Caucasian ever smokers.

RESULTS

The study included 2629 patients, 52.6% Caucasian and 39.3% African-American. The prevalence of ever smokers was 35.8%. There was no significant difference in total SLICC/ACR Damage Index score between ever smokers and never smokers after adjustment for ethnicity, gender, age at diagnosis, and years of education. Ever smokers had more atherosclerotic cardiovascular damage and skin damage compared to non-smokers. Caucasian SLE patients who ever smoked were more likely to have muscle atrophy and atherosclerosis compared to Caucasian non-smokers. African-American patients who ever smoked were more likely to have skin damage compared to African-American non-smokers. African-Americans who smoked were more likely to have many more damage items (cataract, renal damage, pulmonary hypertension, cardiomyopathy, deforming or erosive arthritis, avascular necrosis, skin damage, and diabetes) compared to Caucasians who smoked.

CONCLUSION

Our analysis proved the major effect of smoking on cardiovascular and cutaneous damage. Surprisingly, cardiovascular damage items had higher hazard ratios in Caucasian smokers than non-smokers while skin damage items hazard ratios were higher in African-American smokers compared to non-smokers.Key Points• This study is the largest cohort study to date evaluating the effect of smoking on the cumulative SLICC/ACR Damage Index and its individual damage items.• It is the only study that examined the effect of smoking on individual items of the SLICC/ACR Damage Index in terms of Caucasians vs. African-American ethnicity.• Our analysis proved the major effect of smoking on cardiovascular and cutaneous damage. Compared to non-smokers, Caucasian smokers had higher risk of cardiovascular damage while African-American smokers had more skin damage.• African-Americans who smoked were more likely to have many more damage items (cataract, renal damage, pulmonary hypertension, cardiomyopathy, deforming or erosive arthritis, avascular necrosis, skin damage, and diabetes) compared to Caucasians who smoked.

Association between ambient air pollution and pregnancy rate in women who underwent IVF

STUDY QUESTION

Are the concentrations of five criteria air pollutants associated with probabilities of biochemical pregnancy loss and intrauterine pregnancy in women?

SUMMARY ANSWER

Increased concentrations of ambient particulate matter (PM10), nitrogen dioxide (NO2), carbon monoxide (CO) during controlled ovarian stimulation (COS) and after embryo transfer were associated with a decreased probability of intrauterine pregnancy.

WHAT IS KNOWN ALREADY

Exposure to high ambient air pollution was suggested to be associated with low fertility and high early pregnancy loss in women.

STUDY DESIGN, SIZE, DURATION

Using a retrospective cohort study design, we analysed 6621 cycles of 4581 patients who underwent one or more fresh IVF cycles at a fertility centre from January 2006 to December 2014, and lived in Seoul at the time of IVF treatment.

PARTICIPANTS/MATERIALS, SETTING, METHODS

To estimate patients' individual exposure to air pollution, we computed averages of hourly concentrations of five air pollutants including PM10, NO2, CO, sulphur dioxide (SO2) and ozone (O3) measured at 40 regulatory monitoring sites in Seoul for each of the four exposure periods: period 1 (start of COS to oocyte retrieval), period 2 (oocyte retrieval to embryo transfer), period 3 (embryo transfer to hCG test), and period 4 (start of COS to hCG test). Hazard ratios (HRs) from the time-varying Cox-proportional hazards model were used to estimate probabilities of biochemical pregnancy loss and intrauterine pregnancy for an interquartile range (IQR) increase in each air pollutant concentration during each period, after adjusting for individual characteristics. We tested the robustness of the result using generalised linear mixed model, accounting for within-woman correlation.

MAIN RESULTS AND THE ROLE OF CHANCE

Mean age of the women was 35 years. Average BMI was 20.9 kg/m2 and the study population underwent 1.4 IVF cycles on average. Cumulative pregnancy rate in multiple IVF cycles was 51.3% per person. Survival analysis showed that air pollution during periods 1 and 3 was generally associated with IVF outcomes. Increased NO2 (adjusted HR = 0.93, 95% CI: 0.87, 0.99) and CO (0.94, 95% CI: 0.89, 1.00) during period 1 were associated with decreased probability of intrauterine pregnancy. PM10 (0.92, 95% CI: 0.85, 0.99), NO2 (0.93, 95% CI = 0.86, 1.00) and CO (0.93, 95% CI: 0.87, 1.00) levels during period 3 were also inversely associated with intrauterine pregnancy. Both PM10 (1.17, 95% CI: 1.04 1.33) and NO2 (1.18, 95% CI: 1.03, 1.34) during period 3 showed positive associations with biochemical pregnancy loss.

LIMITATIONS, REASONS FOR CAUTION

The district-specific ambient air pollution treated as an individual exposure may not represent the actual level of each woman's exposure to air pollution. Smoking, working status, parity or gravidity of women, and semen analysis data were not included in the analysis.

WIDER IMPLICATIONS OF THE FINDINGS

This study provided evidence of an association between increased ambient concentrations of PM10, NO2 and CO and reduced probabilities for achieving intrauterine pregnancy using multiple IVF cycle data. Specifically, our results indicated that lower intrauterine pregnancy rates in IVF cycles may be linked to ambient air pollution during COS and the post-transfer period.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2013 R1A6A3A04059017, 2016 R1D1A1B03933410 and 2018 R1A2B6004608) and the National Cancer Center of Korea (NCC-1810220-01). The authors report no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Relationships between intensity, duration, cumulative dose, and timing of smoking with age at menopause: A pooled analysis of individual data from 17 observational studies

BACKGROUND

Cigarette smoking is associated with earlier menopause, but the impact of being a former smoker and any dose-response relationships on the degree of smoking and age at menopause have been less clear. If the toxic impact of cigarette smoking on ovarian function is irreversible, we hypothesized that even former smokers might experience earlier menopause, and variations in intensity, duration, cumulative dose, and age at start/quit of smoking might have varying impacts on the risk of experiencing earlier menopause.

METHODS AND FINDINGS

A total of 207,231 and 27,580 postmenopausal women were included in the cross-sectional and prospective analyses, respectively. They were from 17 studies in 7 countries (Australia, Denmark, France, Japan, Sweden, United Kingdom, United States) that contributed data to the International collaboration for a Life course Approach to reproductive health and Chronic disease Events (InterLACE). Information on smoking status, cigarettes smoked per day (intensity), smoking duration, pack-years (cumulative dose), age started, and years since quitting smoking was collected at baseline. We used multinomial logistic regression models to estimate multivariable relative risk ratios (RRRs) and 95% confidence intervals (CIs) for the associations between each smoking measure and categorised age at menopause (<40 (premature), 40-44 (early), 45-49, 50-51 (reference), and ≥52 years). The association with current and former smokers was analysed separately. Sensitivity analyses and two-step meta-analyses were also conducted to test the results. The Bayesian information criterion (BIC) was used to compare the fit of the models of smoking measures. Overall, 1.9% and 7.3% of women experienced premature and early menopause, respectively. Compared with never smokers, current smokers had around twice the risk of experiencing premature (RRR 2.05; 95% CI 1.73-2.44) (p < 0.001) and early menopause (1.80; 1.66-1.95) (p < 0.001). The corresponding RRRs in former smokers were attenuated to 1.13 (1.04-1.23; p = 0.006) and 1.15 (1.05-1.27; p = 0.005). In both current and former smokers, dose-response relationships were observed, i.e., higher intensity, longer duration, higher cumulative dose, earlier age at start smoking, and shorter time since quitting smoking were significantly associated with higher risk of premature and early menopause, as well as earlier menopause at 45-49 years. Duration of smoking was a strong predictor of age at natural menopause. Among current smokers with duration of 15-20 years, the risk was markedly higher for premature (15.58; 11.29-19.86; p < 0.001) and early (6.55; 5.04-8.52; p < 0.001) menopause. Also, current smokers with 11-15 pack-years had over 4-fold (4.35; 2.78-5.92; p < 0.001) and 3-fold (3.01; 2.15-4.21; p < 0.001) risk of premature and early menopause, respectively. Smokers who had quit smoking for more than 10 years had similar risk as never smokers (1.04; 0.98-1.10; p = 0.176). A limitation of the study is the measurement errors that may have arisen due to recall bias.

CONCLUSIONS

The probability of earlier menopause is positively associated with intensity, duration, cumulative dose, and earlier initiation of smoking. Smoking duration is a much stronger predictor of premature and early menopause than others. Our findings highlight the clear benefits for women of early smoking cessation to lower their excess risk of earlier menopause.

Lifetime number of years of menstruation as a risk index for postmenopausal endometrial cancer in the Norwegian Women and Cancer Study

INTRODUCTION

Lifetime number of years of menstruation (LNYM) reflects a woman's cumulative exposure to endogenous estrogen and can be used as a measure of the combined effect of reproductive factors related to endometrial cancer (EC) risk.

MATERIAL AND METHODS

We aimed to study the association between LNYM and EC risk among postmenopausal women and calculate the population attributable fraction of EC for different LNYM categories. Our study sample consisted of 117 589 women from the Norwegian Women and Cancer (NOWAC) Study. All women were aged 30-70 years at enrollment and completed a baseline questionnaire between 1991 and 2006. Women were followed up for EC to December 2014 through linkages to national registries. We used Cox proportional hazards models to estimate hazard ratios with 95% confidence intervals (95% CIs), adjusted for potential confounders.

RESULTS

In all, 720 women developed EC. We found a statistically significant, positive dose-response relationship between LNYM and EC, with a 9.1% higher risk for each additional year of LNYM (P for trend < .001). Using the LNYM category ≥40 as a reference, the hazard ratios for LNYM <25, 25-29, 30-34, 35-39 were 0.17 (95% CI 0.22-0.27), 0.25 (95% CI 0.17-0.36), 0.43 (95% CI 0.32-0.58), and 0.68 (95% CI 0.51-0.92), respectively. The association between LNYM and EC was independent of incomplete pregnancies, menopausal hormone therapy, diabetes, and body mass index. When considering the population attributable fraction, 67% of EC was estimated to be attributable to LNYM ≥25 years.

CONCLUSIONS

Our study supports that increasing LNYM is an important and independent predictor of EC risk.

Impact of smoking on fertility and age of menopause: a population-based assessment

BACKGROUND AND AIMS

Studies in patients seeking medically assisted reproduction have shown that smoking reduces fertility, but little information is available in the general population. We assessed the associations between smoking and the number of children, childbearing planning and age at menopause in a representative sample of the population of Lausanne, Switzerland.

METHODS

Data from 6711 participants (3530 women, age range 35-75 years) collected between 2003 and 2006 and again in 2009 and 2012. Smoking status, number of offsprings and age of menopause were assessed.

RESULTS

Women who currently smoke had significantly less children than former or never smokers: the number of children per women (average±SD) was 1.38±1.05, 1.45±1.07 and 1.576±1.16, respectively (p<0.001). Women who currently smoke had their first child at an earlier age than the others: 26.7±5.2, 27.4±5.4 and 26.9±5.2 years old for current, former and never smokers, respectively, (p=0.01). Similar findings were found for men: number of children per men 1.475±1.16, 1.67±1.13 and 1.55±1.22 for current, former and never smokers, respectively (p<0.001); no difference was found regarding age at the first child. The difference persisted after multivariate adjustment (adjusted for age, body mass index, Caucasian origins, alcohol consumption, caffeinated drinks consumption, educational level, receiving social help and women taking contraceptives) for the age at first child among women. No association was found between Heaviness of Smoking Index and the number of children among current smokers in both genders. Women who smoke had their menopause more than 1 year prior than never-smoking women (48.9±0.2 years compared with 47.8±0.3 years, respectively, p=0.002).

CONCLUSIONS

Smoking is associated with an earlier age of having the first child and of menopause among women.

Menopausal Age and Chronic Diseases in Elderly Women: A Cross-Sectional Study in Northeast China

Many factors affect menopausal age, and early or late onset of menopause may be associated with many chronic health problems. However, limited data are available regarding this phenomenon in the Northeast China population. For this study, 2011 elderly women were selected as a sample from participants in a cross-sectional survey performed using stratified, clustered multistage, and random sampling methods. Early menopause was more prevalent in subjects born from 1943 to 1947 (OR = 1.708, 95% CI = 1.205, 2.420) and 1933 to 1937 (OR = 2.445, 95% CI: 1.525, 3.921) and in physical laborers (OR = 1.413, 95% CI = 1.021, 1.957). Women with less than nine years of education (OR = 0.515, 95% CI: 0.327, 0.812) and who were current smokers (OR = 0.577, 95% CI: 0.347, 0.959) were less likely to have late menopause. BMIs between 25 and 30 (OR = 1.565, 95% CI: 1.152, 2.125) and greater than 30 (OR = 2.440, 95% CI: 1.482, 4.016) were associated with later menopausal age. Late menopause was positively associated with diabetes (OR = 1.611, 95% CI: 1.142, 2.274) but protective against chronic gastroenteritis/peptic ulcers (OR = 0.533, 95% CI: 0.333, 0.855). Results showed that (1) Being born in an earlier year, having a lower education, and engaging in physical labor were associated with an earlier menopausal age, while a higher BMI was associated with a later menopausal age; and that (2) menopausal age was associated with diabetes and gastroenteritis in elderly women living in Northeast China.

Inhaled medication usage in post-menopausal women and lifetime tobacco smoke exposure: The Women's Health Initiative Observational Study

OBJECTIVE

While active smoking is a causal agent in respiratory disease, the independent role of secondhand smoke (SHS) merits further investigation. We investigated associations between lifetime active smoking and exposure to secondhand smoke - studied independently - and current use of 1 or more inhaled medications as a surrogate for prevalent pulmonary disease in post-menopausal women.

STUDY DESIGN

Information on lifetime active and passive tobacco exposure and inhaled pulmonary medication usage at enrollment was collected from 88,185 postmenopausal women aged 50-79 enrolled in the Women's Health Initiative Observational Study from 1993 to 1998 at 40 centers in the United States. Participants were recruited from localities surrounding the study centers using a variety of methods, including informational mailings and mass media campaigns.

MAIN OUTCOME MEASURES

Multivariate adjusted regression models were used to estimate odds ratios and 95% CI according to levels of active smoking and SHS exposure, and trends were tested across categories.

RESULTS

Ever active smokers had an overall OR of 1.97 (95% CI 1.58-2.45) for having one or more prescribed inhaled medication compared with never-smoking women not exposed to active or passive smoke. The overall OR for using inhalers for never-smoking women exposed to any SHS compared with the same reference group was 1.33 (95% CI 1.07-1.65). In a quantified analysis of SHS, never-smoking women with the highest levels of lifetime SHS exposure had an estimated risk of inhaled medication usage of 1.74 (95% CI 1.32-2.30).

CONCLUSIONS

The risk of requiring one or more prescribed inhaled medications for pulmonary disease was significantly higher in post-menopausal women who ever smoked or who had lifetime exposure to SHS.

A case-control analysis of smoking and breast cancer in African American women: findings from the AMBER Consortium

Recent population studies suggest a role of smoking in the etiology of breast cancer, but few have been conducted among African American women. In a collaborative project of four large studies, we examined associations between smoking measures and breast cancer risk by menopause and hormone receptor status [estrogen receptor-positive (ER+), ER-negative (ER-) and triple-negative (ER-, PR-, HER2-)]. The study included 5791 African American women with breast cancer and 17376 African American controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in multivariable logistic regression analysis with adjustment for study and risk factors. Results differed by menopausal status. Among postmenopausal women, positive associations were observed for long duration and greater pack-years of smoking: relative to never smoking, fully adjusted ORs were 1.14 (95% CI: 1.03-1.26) for duration ≥20 years and 1.16 (95% CI: 1.01-1.33) for ≥20 pack-years. By contrast, inverse associations were observed among premenopausal women, with ORs of 0.80 (95% CI: 0.68-95) for current smoking and 0.81 (95% CI: 0.69-0.96) for former smoking, without trends by duration. Associations among postmenopausal women were somewhat stronger for ER+ breast cancer. The findings suggest that the relation of cigarette smoking to breast cancer risk in African American women may vary by menopausal status and breast cancer subtype.