Time-to-Pregnancy Associated With Couples' Use of Tobacco Products

Time to pregnancy and life expectancy: a cohort study of 18 796 pregnant couples

STUDY QUESTION

Is fecundity, measured as time to pregnancy (TTP), associated with mortality in parents?

SUMMARY ANSWER

Prolonged TTP is associated with increased mortality in both mothers and fathers in a dose-response manner.

WHAT IS KNOWN ALREADY

Several studies have linked both male and female fecundity to mortality. In women, infertility has been linked to several diseases, but studies suggest that the underlying conditions, rather than infertility, increase mortality.

STUDY DESIGN, SIZE, DURATION

A prospective cohort study was carried out on 18 796 pregnant couples, in which the pregnant women attended prophylactic antenatal care between 1973 and 1987 at a primary and tertiary care unit. The couples were followed in Danish mortality registers from their child's birth date until death or until 2018. The follow-up period was up to 47 years, and there was complete follow-up until death, emigration or end of study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

At the first antenatal visit, the pregnant women were asked to report the time to the current pregnancy. Inclusion was restricted to the first pregnancy, and TTP was categorised into <12 months, ≥12 months, not planned, and not available. In sub-analyses, TTP ≥12 was further categorized into 12-35, 36-60, and >60 months. Information for parents was linked to several Danish nationwide health registries. Survival analysis was used to estimate the hazard ratios (HRs) with a 95% CI for survival and adjusted for age at the first attempt to become pregnant, year of birth, socioeconomic status, mother's smoking during pregnancy, and mother's BMI.

MAIN RESULTS AND THE ROLE OF CHANCE

Mothers and fathers with TTP >60 months survived, respectively, 3.5 (95% CI: 2.6-4.3) and 2.7 (95% CI: 1.8-3.7) years shorter than parents with a TTP <12 months. The mortality was higher for fathers (HR: 1.21, 95% CI: 1.09-1.34) and mothers (HR: 1.29, 95% CI: 1.12-1.49) with TTP ≥12 months compared to parents with TTP <12 months. The risk of all-cause mortality during the study period increased in a dose-response manner with the highest adjusted HR of 1.98 (95% CI: 1.62-2.41) for fathers and 2.03 (95% CI: 1.56-2.63) for mothers with TTP >60 months. Prolonged TTP was associated with several different causes of death in both fathers and mothers, indicating that the underlying causes of the relation between fecundity and survival may be multi-factorial.

LIMITATIONS, REASONS FOR CAUTION

A limitation is that fecundity is measured using a pregnancy-based approach. Thus, the cohort is conditioned on fertility success and excludes sterile couples, unsuccessful attempts and spontaneous abortions. The question used to measure TTP when the pregnant woman was interviewed at her first attended prophylactic antenatal care: 'From the time you wanted a pregnancy until it occurred, how much time passed?' could potentially have led to serious misclassification if the woman did not answer on time starting unprotected intercourse but on the start of wishing to have a child.

WIDER IMPLICATIONS OF THE FINDINGS

We found that TTP is a strong marker of survival, contributing to the still-emerging evidence that fecundity in men and women reflects their health and survival potential.

STUDY FUNDING/COMPETING INTEREST(S)

The authors acknowledge an unrestricted grant from Ferring. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article, or the decision to submit it for publication. M.L.E. is an advisor to Ro, VSeat, Doveras, and Next.

TRIAL REGISTRATION NUMBER

N/A.

Deafening Silence of Male Infertility

Think about 6 loved ones of reproductive age in your life. Now imagine that 1 of these 6 individuals is suffering from infertility. Perhaps they feel alone and isolated, unable to discuss their heartbreak with their closest friends, family, and support network. Suffering in silence. In this editorial, we discuss the infertility journey through the lens of the patients, the providers, and the scientists who struggle with infertility each and every day. Our goal is to open a dialogue surrounding infertility, with an emphasis on dismantling the longstanding societal barriers to acknowledging male infertility as a disease. Through education, communication, compassion, and advocacy, together we can all begin to break the deafening silence of male infertility.

Paternal preconception modifiable risk factors for adverse pregnancy and offspring outcomes: a review of contemporary evidence from observational studies

BACKGROUND

The preconception period represents transgenerational opportunities to optimize modifiable risk factors associated with both short and long-term adverse health outcomes for women, men, and children. As such, preconception care is recommended to couples during this time to enable them to optimise their health in preparation for pregnancy. Historically, preconception research predominately focuses on maternal modifiable risks and health behaviours associated with pregnancy and offspring outcomes; limited attention has been given to inform paternal preconception health risks and outcomes. This systematic review aims to advance paternal preconception research by synthesising the current evidence on modifiable paternal preconception health behaviours and risk factors to identify associations with pregnancy and/or offspring outcomes.

METHODS

Medline, Embase, Maternity and Infant care, CINAHL, PsycINFO, Scopus, and ISI Proceedings were searched on the 5^th of January 2023, a date limit was set [2012-2023] in each database. A Google Scholar search was also conducted identifying all other relevant papers. Studies were included if they were observational, reporting associations of modifiable risk factors in the preconception period among males (e.g., identified as reproductive partners of pregnant women and/or fathers of offspring for which outcomes were reported) with adverse pregnancy and offspring outcomes. Study quality was assessed using the Newcastle-Ottawa Scale. Exposure and outcome heterogeneity precluded meta-analysis, and results were summarised in tables.

RESULTS

This review identified 56 cohort and nine case control studies. Studies reported on a range of risk factors and/or health behaviours including paternal body composition (n = 25), alcohol intake (n = 6), cannabis use (n = 5), physical activity (n = 2), smoking (n = 20), stress (n = 3) and nutrition (n = 13). Outcomes included fecundability, IVF/ISCI live birth, offspring weight, body composition/BMI, asthma, lung function, leukemia, preterm birth, and behavioural issues. Despite the limited number of studies and substantial heterogeneity in reporting, results of studies assessed as good quality showed that paternal smoking may increase the risk of birth defects and higher paternal BMI was associated with higher offspring birthweight.

CONCLUSION

The current evidence demonstrates a role of paternal preconception health in influencing outcomes related to pregnancy success and offspring health. The evidence is however limited and heterogenous, and further high-quality research is needed to inform clinical preconception care guidelines to support men and couples to prepare for a health pregnancy and child.

Preconceptional thyroid stimulating hormone level and fecundity: a community-based cohort study of time to pregnancy

OBJECTIVE

To investigate the association between preconception thyroid stimulating hormone (TSH) level and time to pregnancy within a community-based population.

DESIGN

A community-based cohort study.

SETTING

Two free preconception check-up centers.

PATIENT(S)

Women who enrolled in the National Free Preconception Check-up Projects from January 1, 2018 to December 31, 2018 in Tianhe and Zengcheng districts of Guangzhou city.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Time to pregnancy.

RESULT(S)

A total of 1,478 women were eligible for the analysis; of these, 1,401 had a preconception TSH level within the range of 0.50 and 5.59 mIU/L (2.5th-97.5th percentiles) were taken as target study population. Among them, 968 (69.1%) couples achieved pregnancy within the first 6 months and 1,082 (77.2%) within 12 months. Dichotomized by the recommended cut-off value of 2.5 mIU/L, the percentage of women conceived in the high TSH level category (2.50-5.59 mIU/L) was comparable to that of the low category (0.50-2.49 mIU/L) (79.0% vs. 78.1%), with a crude fecundity odd ratio of 0.99 (95% confidence interval at 0.87-1.13). No statistically significant difference was observed after the adjustment in all models. Continuous TSH level was further examined, and the nonlinear association between TSH level and fecundity odds ratios was of no statistical significance.

CONCLUSION(S)

Preconception TSH level was not associated with fecundity in a healthy community-based population. Women attempting pregnancy with a TSH level ≥ 2.5 mIU/L can be reassured that they are unlikely to have an increased time to pregnancy.

Environmental toxicants and male fertility

Semen quality has declined especially among Western men. Experimental and epidemiological studies have shown potential links between exposure to environmental toxicants and poor male fertility. Some environmental exposures in utero can disrupt fetal testicular function and result in cryptorchidism, low semen quality, low serum testosterone levels, and low fertility. Environmental exposure in childhood and adulthood can also adversely affect germ cells, Sertoli cells, Leydig cells, or the hypothalamic-pituitary-testicular axis, resulting in impaired male fertility. In this review, we report the latest results from human studies that investigated the role of endocrine disrupting chemicals, heavy metals, tobacco smoking, alcohol drinking, and use of marijuana in low semen quality and impaired male fertility. Current evidence suggests the relationship between these environmental factors and low male fertility; however, some factors showed conflicting results which need further investigation.

Effect of paternal smoking on pre-implantation embryonic development: a prospective cohort study

CONTEXT

Recent studies have failed to demonstrate the negative impact of male tobacco smoking on embryo development, raising the question of its actual implication on natural fecundity and assisted reproductive techniques outcomes.

AIMS

To assess the impact of paternal smoking on embryo development.

METHODS

In this prospective cohort study, 252 men from couples undergoing in vitro fertilisation (IVF) were included. Each patient was interviewed and took a carbon monoxide breath-test, creating three groups: non-smokers (n=113), former smokers (n=81) and active smokers (n=58). The Top-grade embryo ratio (primary endpoint), embryo morphokinetic parameters and clinical outcomes were assessed.

KEY RESULTS

In a multivariate analyses based on 1521 embryos, no significant difference was found in the top-grade embryo ratio between the groups. Tobacco smoking had no impact on clinical outcomes. Compared to non-smokers the time to the pronuclei fading (tPNf, P=0.006) and the time to the first embryonic cleavage (t2, P=0.002) were shorter in smokers, and the t2 was also slightly shorter in former smokers (P=0.045). No other differences were found in the morphokinetic parameters.

CONCLUSION

Even if a few differences were observed in the first timing of embryonic events, this study did not highlight a major embryonic and clinical impact of the paternal smoking status.

IMPLICATION

The results obtained here are reassuring towards IVF outcomes. As maternal smoking is highly controlled in the IVF patients in this study, we speculate that the sperm selection process may limit the adverse effects of tobacco consumption on embryo development.

Multiple Targets of Toxicity in Environmental Exposure to Low-Dose Cadmium

Dietary assessment reports and population surveillance programs show that chronic exposure to low levels of environmental cadmium (Cd) is inevitable for most people, and adversely impacts the health of children and adults. Based on a risk assessment model that considers an increase in the excretion of β₂-microglobulin (β₂M) above 300 μg/g creatinine to be the "critical" toxicity endpoint, the tolerable intake level of Cd was set at 0.83 µg/kg body weight/day, and a urinary Cd excretion rate of 5.24 µg/g creatinine was considered to be the toxicity threshold level. The aim of this review is to draw attention to the many other toxicity endpoints that are both clinically relevant and more appropriate to derive Cd exposure limits than a β₂M endpoint. In the present review, we focus on a reduction in the glomerular filtration rate and diminished fecundity because chronic exposure to low-dose Cd, reflected by its excretion levels as low as 0.5 µg/g creatinine, have been associated with dose-dependent increases in risk of these pathological symptoms. Some protective effects of the nutritionally essential elements selenium and zinc are highlighted. Cd-induced mitochondrial dysfunction is discussed as a potential mechanism underlying gonadal toxicities and infertility.

Does Older Age Modify Associations between Endocrine Disrupting Chemicals and Fecundability?

Urinary concentrations of several endocrine disrupting chemicals, including phthalate metabolites, bisphenol A (BPA), and benzophenone (BP)-type ultraviolet (UV) filters, have been associated with a longer time-to-pregnancy (TTP). Potential modification of these associations by couple’s age has not been studied. TTP was defined as the number of prospectively observed menstrual cycles a couple attempted pregnancy until the occurrence of a human chorionic gonadotropic-detected pregnancy. Urinary concentrations of two BP-type UV filters and three phthalate metabolites were measured at baseline. Fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated for each chemical adjusting for age, body mass index, serum cotinine, creatinine, and accounting for right censoring and left truncation. Models evaluated effect modification between EDC concentrations and TTP by partner’s age, dichotomized at 35 years. Separate models were run for male and female partners. No significant effect modification was observed for any EDC for either partner, but data were suggestive of a longer TTP among females aged ≥35 years, particularly for BP-2 (FOR = 0.61, 95% CI 0.36, 1.05) and 4-hydroxybenzophenone (FOR = 0.71, 95% CI: 0.46, 1.09) reflecting 39% and 29% reductions in fecundability, respectively. We saw no evidence of effect modification by couples’ age on associations between TTP and urinary phthalate or BPA metabolite concentrations. Across the EDCs we examined, we found little evidence that age modifies TTP-exposure associations.

The current situation and future directions for the study on time-to-pregnancy: a scoping review

Introduction

As problems associated with infertility and population aging increase, there is a growing interest in the factors that cause a decline in human fertility. Time-to-pregnancy (TTP) is a good indicator with which to reflect human fecundability. Here, we present a comprehensive overview of this topic.

Methods

Relevant qualitative and quantitative studies were identified by searching the Web of science and PubMed electronic databases. We included all literature, written in English, from inception to the 10th April 2021 providing the focus was on TTP. We conducted a narrative synthesis using thematic analysis.

Results

Traditional TTP-related study protocols include prospective and retrospective cohorts that provide a wealth of data to reveal potential influences on TTP. Thus far, a variety of factors have been shown to be associated with TTP in couples preparing for pregnancy, including basic demographic characteristics, menstrual status, chronic disease status, environmental endocrine disruptor exposure, and lifestyles. However, there are inevitable epidemiological bias in the existing studies, including recall bias, selection bias and measurement bias. Some methodological advances have brought new opportunities to TTP research, which make it possible to develop precision interventions for population fertility. Future TTP studies should take advantage of artificial intelligence, machine learning, and high-throughput sequencing technologies, and apply medical big data to fully consider and avoid possible bias in the design.

Conclusion

There are many opportunities and future challenges for TTP related studies which would provide a scientific basis for the “precise health management” of the population preparing for pregnancy.

As the problems of infertility and population aging increase, there is a growing interest in the factors that cause a decline in human fertility. Time-to-pregnancy (TTP) is a good indicator with which to reflect human fecundability, and a longer TTP is known to reflect a reduction in fertility. Many original studies, with different designs, have used TTP to explore the factors that might influence fertility, including basic demographic characteristics, chronic disease status, environmental endocrine disruptor exposure, and lifestyles. However, much of the existing evidence is inconsistent and limited by various types of bias. This review provides a synopsis of recent TTP studies, and highlights new opportunities and future challenges.

Environmental factors in declining human fertility

A severe decline in child births has occurred over the past half century, which will lead to considerable population declines, particularly in industrialized regions. A crucial question is whether this decline can be explained by economic and behavioural factors alone, as suggested by demographic reports, or to what degree biological factors are also involved. Here, we discuss data suggesting that human reproductive health is deteriorating in industrialized regions. Widespread infertility and the need for assisted reproduction due to poor semen quality and/or oocyte failure are now major health issues. Other indicators of declining reproductive health include a worldwide increasing incidence in testicular cancer among young men and alterations in twinning frequency. There is also evidence of a parallel decline in rates of legal abortions, revealing a deterioration in total conception rates. Subtle alterations in fertility rates were already visible around 1900, and most industrialized regions now have rates below levels required to sustain their populations. We hypothesize that these reproductive health problems are partially linked to increasing human exposures to chemicals originating directly or indirectly from fossil fuels. If the current infertility epidemic is indeed linked to such exposures, decisive regulatory action underpinned by unconventional, interdisciplinary research collaborations will be needed to reverse the trends.

Evidence for Ovarian and Testicular Toxicities of Cadmium and Detoxification by Natural Substances

Cadmium (Cd) is an environmental toxicant, capable of reducing mitochondrial ATP production and promoting the formation of reactive oxygen species (ROS) with resultant oxidative stress conditions. The ovary and testis are the primary gonads in which female gametes (oocytes) and male gametes (spermatozoa), estrogen and testosterone are produced. These organs are particularly susceptible to Cd cytotoxicity due to their high metabolic activities and high energy demands. In this review, epidemiological and experimental studies examining Cd toxicities in gonads are highlighted together with studies using zinc (Zn), selenium (Se), and natural substances to reduce the effects of Cd on follicular genesis and spermatogenesis. Higher blood concentrations of Cd ([Cd]b) were associated with longer time-to-pregnancy in a prospective cohort study. Cd excretion rate (ECd) as low as 0.8 μg/g creatinine was associated with reduced spermatozoa vitality, while Zn and Se may protect against spermatozoa quality decline accompanying Cd exposure. ECd > 0.68 µg/g creatinine were associated with an increased risk of premature ovarian failure by 2.5-fold, while [Cd]b ≥ 0.34 µg/L were associated with a 2.5-fold increase in the risk of infertility in women. Of concern, urinary excretion of Cd at 0.68 and 0.8 μg/g creatinine found to be associated with fecundity are respectively 13% and 15% of the conventional threshold limit for Cd-induced kidney tubular effects of 5.24 μg/g creatinine. These findings suggest that toxicity of Cd in primary reproductive organs occurs at relatively low body burden, thereby arguing for minimization of exposure and environmental pollution by Cd and its transfer to the food web.

Association between exposure to ambient air pollutants and the outcomes of in vitro fertilization treatment: A multicenter retrospective study

BACKGROUND

Exposure to ambient air pollution has been reported to be inversely correlated with human reproductive health. However, the results of previous studies exploring the association between air pollution and in vitro fertilization (IVF) outcomes are conflicting, and further research is needed to clarify this association.

OBJECTIVES

This study aimed to investigate the associations between exposure to air pollutants and IVF outcomes.

METHODS

We conducted a multicenter retrospective cohort study involving 20,835 patients from four cities in Northern China, contributing to 11,787 fresh embryo transfer cycles, 9050 freeze-all cycles, and 17,676 frozen-thawed embryo transfer (FET) cycles during 2014-2018. We calculated the daily average concentrations of six criteria air pollutants (PM_2.5, PM₁₀, O₃, NO₂, CO, and SO₂) during different exposure windows in IVF treatment timeline using data from the air monitoring station nearest to the residential site as approximate individual exposure. Generalized estimation equation models were used to assess the association between air pollution exposure and IVF outcomes.

RESULTS

Exposure to O₃, NO₂, and CO during most exposure windows in fresh embryo transfer cycles were correlated with lower possibilities of biochemical pregnancy, clinical pregnancy, and live birth. An inverse association of exposure to O₃ and SO₂ with pregnancy outcomes was observed in FET cycles. In addition, we found a significant association of exposure to air pollutants with a higher risk of ectopic pregnancy and lower oocyte yield.

CONCLUSIONS

Our study provided large-scale human evidence of the association between air pollution and adverse human reproductive outcomes in the population opting for IVF. Thus, exposure to air pollutants in the population opting for IVF should be limited to improve treatment outcomes.

Impaired fecundity as a marker of health and survival: a Danish twin cohort study

STUDY QUESTION

Is fecundity, measured as self-reported time to first pregnancy (TTP), a marker for subsequent health and survival?

SUMMARY ANSWER

Long TTP was a marker for increased mortality among women and higher hospitalization rates for both women and men.

WHAT IS KNOWN ALREADY

Poor semen quality has been linked to increased mortality and morbidity from a wide range of diseases. Associations among fecundity, health and survival among women are still uncertain and studies on actual measures of fecundity and health outcomes are rare.

STUDY DESIGN, SIZE, DURATION

We performed a prospective cohort study of 7825 women and 6279 men, aged 18 and above with measures on first TTP, who participated in one of the Danish nation-wide twin surveys in 1994 (twins born 1953-1976) and 1998 (twins born 1931-1952). They were followed-up for mortality and hospital admissions from the interview until 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Twins were identified in the Danish Twin Registry and linked to Danish registers. TTP was restricted to the first pregnancy as a categorical outcome with cut-off points at 2, 10 and 18 months. We analysed the association between TTP and survival using a Cox proportional hazards model estimating hazards ratios (HRs) with 95% confidence intervals (CIs). Fine-Gray survival models were used to estimate sub-hazard ratios for specific causes of death allowing for competing risks. Using negative binomial regression, we estimated incidence rate ratios (IRRs) with 95% CIs for all-cause and cause-specific hospitalizations. All analyses were stratified by sex and adjusted for age at interview, birth cohorts, age at first attempt to become pregnant, smoking, years in school and BMI.

MAIN RESULTS AND THE ROLE OF CHANCE

In the total study population, 49.9% of women and 52.7% of men reported a TTP of less than 2 months, 30.8% of women and 29.6% of men reported a TTP of 2-9 months, 6.6% of women and 5.7% of men reported a TTP of 10-17 months, and 13.3% of women and 12.0% of men reported a TTP of 18 months or more. Among 1305 deaths, we found a higher mortality for women (HR = 1.46; 95% CI 1.15, 1.87) with a TTP of ≥18 months relative to those with a TTP of <2 months, while the highest mortality was indicated for men with a TTP of 10-17 months (HR = 1.31; 95% CI 0.98, 1.74). Among 53 799 hospitalizations, we found an increased hospitalization rate among women (HR = 1.21; 95% CI 1.0-1.41) and men (HR = 1.16; 95% CI 1.00-1.35) with a TTP of ≥18 months, and for men with a TTP of 2-9 months (HR = 1.14; 95% CI 1.01-1.30). A dose-response relationship was found for women regarding both mortality (P = 0.022) and hospitalizations (P = 0.018). Impaired fecundity was associated with a wide range of diseases and some causes of death, indicating a multi-factorial causal influence on fecundity, especially among women.

LIMITATIONS, REASONS FOR CAUTION

A major limitation was that fecundity depends on both partners, which was not considered in this study. Moreover, we could not obtain information on a number of potential confounders.

WIDER IMPLICATIONS OF THE FINDINGS

Fecundity seems positively correlated with overall health and may be a universal marker of future health and survival. These results add knowledge to the limited findings showing that reduced fecundity in women and poor semen quality in men may reflect worse health and a shorter life, particularly among women.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by NIH grant HD096468 (M.L.E., T.K.J. and R.L.J.). The authors declare that they have no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Agriculture Exposure and Time to Pregnancy Among Women Enrolled in the French Prospective Cohort AGRICAN

OBJECTIVES

In few retrospective studies, prolonged time-to-pregnancy (TTP) was observed for women exposed to pesticides especially in flower production. The present study investigated time-to-pregnancy in the AGRICAN cohort.

METHODS

Analyses were performed on 616 women reporting a pregnancy (2005 to 2017), and data on agricultural activities performed before the last pregnancy was retrospectively collected. Fecundability odds ratios (fOR) were estimated using a discrete time analogue of Cox proportional hazard model adjusted on maternal and paternal age, body mass index (BMI), and alcohol consumption.

RESULTS

A decrease in fecundability was non-significantly associated with farm work (adjusted fOR = 0.86; 95% confidence interval [CI]: 0.71 to 1.05). Decreases were also observed for nightwork (afOR = 0.75; 95% CI: 0.49 to 1.15) and exposure to vibrations (afOR = 0.68; 95% CI: 0.43 to 1.09).

CONCLUSION

Women working on a farm before conception appeared to experience a longer TTP. Negative associations were suggested for some agricultural activities and working conditions.

Electronic Cigarettes and Fecundability: Results From a Prospective Preconception Cohort Study

Although electronic cigarette (e-cigarette) aerosol contains similar toxicants to combustible cigarettes, few studies have examined their influence on fecundability. We assessed the association between e-cigarette use and fecundability, overall and according to combustible cigarette smoking history, in a cohort of 4,586 North American women (aged 21-45 years) enrolled during 2017-2020 in Pregnancy Study Online, a Web-based prospective preconception study. Women reported current and former e-cigarette use on baseline and follow-up questionnaires, and they completed bimonthly follow-up questionnaires until self-reported pregnancy or censoring. Fecundability ratios and 95% confidence intervals were calculated using proportional probabilities models, controlling for potential confounders. Overall, 17% of women had ever used e-cigarettes and 4% were current users. Compared with never use of e-cigarettes, current e-cigarette use was associated with slightly lower fecundability (fecundability ratio = 0.84, 95% confidence interval (CI): 0.67, 1.06). Compared with current nonusers of e-cigarettes and combustible cigarettes, fecundability ratios were 0.83 (95% CI: 0.54, 1.29) for current dual users of e-cigarettes and combustible cigarettes, 0.91 (95% CI: 0.70, 1.18) for current e-cigarette users who were nonsmokers of combustible cigarettes, and 1.01 (95% CI: 0.85, 1.20) for nonusers of e-cigarettes who were current smokers of combustible cigarettes. Current e-cigarette use was associated with slightly reduced fecundability, but estimates of its independent and joint associations with combustible cigarette smoking were inconsistent and imprecise.

A qualitative study of factors influencing male participation in fertility research

BACKGROUND

Although fertility is a couple-based outcome, fertility studies typically include far fewer males than females. We know little about which factors facilitate or inhibit male participation in fertility research. In this study we aimed to explore factors that influence male participation in fertility research among North American couples trying to conceive.

METHODS

We conducted a qualitative research study of male participation in Pregnancy Study Online (PRESTO), a prospective preconception cohort of couples actively trying to conceive in Canada and the United States. Between January-August 2019, we carried out 14 online one-on-one in-depth interviews and one online focus group of males and females with varying levels of participation. The in-depth interviews included females who enrolled in PRESTO but declined to invite their male partners to participate (n = 4), males who enrolled in PRESTO (n = 6), and males who declined to participate in PRESTO (n = 4). The focus group included 10 males who enrolled in PRESTO. We analyzed the transcriptions using inductive content analysis.

RESULTS

Male and female participants perceived that fertility is a women's health issue and is a difficult topic for men to discuss. Men expressed fears of infertility tied to masculinity. However, men were motivated to participate in fertility research to support their partners, provide data that could help others, and to learn more about their own reproductive health.

CONCLUSIONS

Male participation in fertility studies will improve our understanding of male factors contributing to fertility and reproductive health issues. Results indicate a need for more education and health communication on male fertility to normalize male participation in fertility and reproductive health research. Men are much less likely than women to participate in research on fertility and pregnancy. However, it is important for men to participate in fertility research so that we gain a better understanding of male factors that impact fertility and pregnancy outcomes. In this qualitative study, we interviewed men and women from Canada and the United States who were trying to become pregnant to understand why men choose to participate in fertility research, why men choose not to participate in fertility research, and why women choose not to invite their male partners to participate in fertility research. We found that both men and women believe fertility is a woman's health issue. Men find it difficult to talk about pregnancy and fertility and have fears of infertility tied to masculinity. However, men are motivated to participate in fertility research to support their partners, to help others, and to learn more about their own reproductive health.

Sub-fecundity and associated factors among mothers with natural planned conception attending antenatal care service in Arba Minch Health Facilities

Background

Fecundity is a physiological ability to have children. The inability to get the desired child which was commonly caused by the prolonged time to conceive due to unwanted non-conception period increased from time to time. As a result, many couples are developing psychological, social, and economic problems and unstable life. However, information on fecundity status is limited in Ethiopia context. Therefore, this study aimed to assess the proportion of sub-fecundity and associated factors in Ethiopia context.

Methods

A health institution based cross-sectional study was conducted in Arba Minch health facilities from March 25 to April 25, 2020. By using a systematic sampling method, 539 mothers were selected for the study. Structured questionnaire was used for data collection. A binary logistic regression model was used to identify factors associated with the sub-fecundity. Variables with p-value <0.25 in the bi-variable logistic regression analysis were interred and checked for association in a multivariable logistic regression model. The level of statistical significance was declared at p-value <0.05.

Result

The proportion of sub-fecundity was 17.8% with 95%CI (14.8%-21.3%). Mothers’ age ≥ 30 (AOR = 2.54, 95%CI; 1.18–5.48), partners’ age ≥ 35 (AOR = 2.20, 95%CI; 1.01–4.75), coffee consumption of ≥ 4 cups/day (AOR = 2.93, 95%CI; 1.14–7.53), menses irregularity (AOR = 3.79 95%CI; 2.01–7.14) and coital frequency of 1day/week (AOR = 3.65, 95%CI; 1.47–9.05) were significantly associated with the sub-fecundity.

Conclusion

This study found that a substantial proportion of mothers were sub-fecund. Factors that contributed to the sub-fecundity were pre-pregnancy; mothers’ age, partners’ age, coffee drinking of ≥ 4 cups/day, coital frequency of 1day/week, and menses irregularity. Thus, efforts to prevent sub-fecundity should focus on awareness creation as to plan to conceive at early age, reducing coffee consumption, increasing days of coital frequency per week, and investigating and treating mothers with irregular menses.

Associations of toxic and essential trace elements in serum, follicular fluid, and seminal plasma with In vitro fertilization outcomes

Toxic and essential trace elements are associated with human fertility. However, limited studies have been conducted on the relationship between trace elements and in vitro fertilization (IVF) outcomes in the Chinese population. In this exploratory study, 103 couples who underwent IVF/intracytoplasmic sperm injection (ICSI) treatment in our reproductive center were recruited. Serum and follicular fluid (FF) samples and seminal plasma samples were collected from the female and male partners, respectively, on the day of oocyte retrieval. Concentrations of chromium (Cr), nickel (Ni), arsenic (As), selenium (Se), cadmium (Cd), and lead (Pb) in the specimens were measured by inductively coupled plasma-mass spectrometry. Generalized linear models were used to evaluate the associations of toxic and essential trace element levels with the intermediate parameters and outcomes of IVF at both the sex-specific and couple levels. The Cr level in the serum of the female partners was inversely associated with the count of mature oocytes retrieved (p for trend = 0.033). In terms of embryo development, As concentrations in female serum and FF were inversely associated with the probabilities to obtain good-quality cleavage embryos (p for trend < 0.01). There were significant correlations between follicular Se concentrations and seminal As concentrations and higher quality cleavage embryos (p for trend < 0.01). Moreover, a positive correlation was observed between the female serum Se concentrations and blastocyst formation (p for trend = 0.031). In contrast, a higher follicular Se level was negatively correlated with embryo development at the blastocyst stage (p for trend < 0.01). Regarding the clinical outcomes, a positive association of Se levels in seminal plasma and a negative association of follicular Cd levels was observed with the probabilities of pregnancy (p for trend = 0.006 and 0.035, respectively) and live birth (p for trend = 0.014 and 0.027, respectively). The results indicate that exposure to toxic elements (Cr, As and Cd) is associated with intermediate parameters and outcomes of IVF. Furthermore, male Se exposure may be related to better pregnancy outcomes.

Prospective study of cigarette smoking and fecundability

STUDY QUESTION

To what extent is cigarette smoking associated with reduced fecundability?

SUMMARY ANSWER

Current female smokers, particularly those who had smoked ≥10 cigarettes/day for ≥10 years, had lower fecundability than never smokers, but current male smoking and passive smoking in either partner showed little association with reduced fecundability.

WHAT IS KNOWN ALREADY

Female smoking has been identified as a cause of infertility, yet there has been limited characterization of the dose and duration at which an effect is observed. Results for male active smoking and passive smoking in both partners are less consistent.

STUDY DESIGN, SIZE, DURATION

We analyzed data from a North American internet-based preconception cohort study of 5473 female and 1411 male pregnancy planners, enrolled from 2013 to 2018. Participants had been attempting conception for ≤6 menstrual cycles at study entry.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We collected information on active and passive smoking history on baseline questionnaires. Pregnancy was reported on female bi-monthly follow-up questionnaires. We calculated fecundability ratios (FR) and 95% CI using proportional probabilities regression models, adjusted for demographic, behavioral, medical, reproductive and dietary variables.

MAIN RESULTS AND THE ROLE OF CHANCE

Female current regular smoking (FR = 0.90, 95% CI: 0.77, 1.07), current occasional smoking (FR = 0.88, 95% CI: 0.73, 1.06), and former smoking (FR = 0.89, 95% CI: 0.81, 0.98) were associated with small reductions in fecundability. Results were stronger among women who smoked ≥10 cigarettes/day for ≥10 years (FR = 0.77, 95% CI: 0.53, 1.10). Male current regular and former smoking, and current passive smoking in either partner were not meaningfully associated with reduced fecundability. In utero exposure to ≥10 cigarettes/day among females was associated with reduced fecundability (FR = 0.75, 95% CI: 0.52, 1.06).

LIMITATIONS, REASONS FOR CAUTION

Numbers of cigarette smokers, particularly within categories of intensity and duration, were small. Under-reporting of smoking may have resulted in non-differential misclassification, and smokers were more likely to be lost to follow-up.

WIDER IMPLICATIONS OF THE FINDINGS

Given the consistency of our findings with results from previous studies and our observation of a dose-response relation in intensity of smoking, this study supports an association between female cigarette smoking and lower fecundability.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the National Institute of Child Health and Human Development (R01-HD086742, R21-HD072326, R03-HD090315 and T32-HD052458). The authors declare no competing interests.

Environmental & occupational exposure & female reproductive dysfunction

All individuals are exposed to certain chemical, physical, biological, environmental as well as occupational factors. The data pertaining to role of these factors on female reproduction are scanty as compared to male. The available data suggest the adverse effects of certain toxicants, viz., metals such as lead, cadmium and mercury, pesticides such as bis(4-chlorophenyl)-1,1,1-trichloroethane and organic solvent such as benzene, toluene and ionizing radiation on the female reproductive system affecting directly the organ system or impacting in directly through hormonal impairments, molecular alterations, oxidative stress and DNA methylation impairing fertility as well as pregnancy and its outcomes. Thus, there is a need for awareness and prevention programme about the adverse effects of these factors and deterioration of female reproductive health, pregnancy outcome and offspring development as some of these chemicals might affect the developing foetus at very low doses by endocrine disruptive mechanism.

Semen quality and cigarette smoking in a cohort of healthy fertile men

BACKGROUND

Numerous health effects of smoking are well-known; associations with semen quality are uncertain. Most previous studies did not adjust for potential confounders and had limited information on age at smoking initiation or smoking cessation.

METHODS

We investigated 1,631 healthy fertile men in the Nanjing Medical University Longitudinal Investigation of Fertility and the Environment (NMU-LIFE) study. Relationships were examined using multivariable linear regression controlling for potential covariates.

RESULTS

We found a significant decrease in semen volume (β = -0.10, P = 0.001) and total sperm count (β = -0.42, P = 0.037), and significant increase in total motility (β = 6.02, P = 0.037) and progressive motility (β = 5.52, P = 0.037) in ever smokers of pack-years ≥10 compared with never smokers. We observed an inverse dose-dependent relation between smoking pack-years and semen volume (P < 0.001) and total sperm count (P = 0.010) and a positive dose-dependent relation between smoking pack-years and both total motility and progressive motility (P = 0.042 and 0.048, respectively). No significant differences in semen quality were detected among ever smokers with different ages at smoking initiation nor in former smokers compared with never smokers.

CONCLUSIONS

Cigarette smoking was associated with lower semen volume and total sperm count and higher sperm motility. Smoking cessation might have a restorative effect on semen quality. This finding has important implications for public health research and for understanding the development of abnormal semen quality.

The impact of maternal lifestyle factors on periconception outcomes: a systematic review of observational studies

The main risk factors for important reproductive health issues such as subfertility and perinatal mortality largely originate in the periconception period. To evaluate associations between modifiable maternal lifestyle factors and periconception outcomes, a systematic search was conducted for relevant studies published from 1990 to February 2017 on Embase, Medline, Web of Science, Cochrane database, PubMed and Google Scholar. The initial search identified 6166 articles, of which 49 studies were eligible for inclusion. Fecundity (the capacity to have a live birth) showed significant inverse associations with smoking, alcohol use and poor diet. Studies regarding time to pregnancy showed a decline in fecundity ratios (the monthly conception rate among exposed relative to unexposed couples) with increasing body mass index (BMI). Furthermore, risk of first-trimester miscarriage was found to be increased in smokers, alcohol and caffeine consumers, and with increasing BMI. Vitamin supplement use showed a decrease in this risk. This review demonstrates that maternal modifiable lifestyle factors affect periconception outcomes. If couples planning a pregnancy are more aware and supported to adopt healthy lifestyles during the periconceptional 'window of opportunity', short-term reproductive health as well as health in later life and even of future generations can be further improved.

Smoke, alcohol and drug addiction and male fertility

In recent decades, the decline in human fertility has become increasingly more worrying: while therapeutic interventions might help, they are vexing for the couple and often burdened with high failure rates and costs. Prevention is the most successful approach to fertility disorders in males and females alike. We performed a literature review on three of the most common unhealthy habits - tobacco, alcohol and drug addiction - and their reported effects on male fertility. Tobacco smoking is remarkably common in most first-world countries; despite a progressive decline in the US, recent reports suggest a prevalence of more than 30% in subjects of reproductive age - a disturbing perspective, given the well-known ill-effects on reproductive and sexual function as well as general health. Alcohol consumption is often considered socially acceptable, but its negative effects on gonadal function have been consistently reported in the last 30 years. Several studies have reported a variety of negative effects on male fertility following drug abuse - a worrying phenomenon, as illicit drug consumption is on the rise, most notably in younger subjects. While evidence in these regards is still far from solid, mostly as a result of several confounding factors, it is safe to assume that cessation of tobacco smoking, alcohol consumption and recreational drug addiction might represent the best course of action for any couple trying to achieve pregnancy.

Partner smoking influences whether mothers quit smoking during pregnancy: a prospective cohort study

OBJECTIVE

To analyse the prevalence and intensity of smoking among pregnant women and their partners, and factors associated with quitting smoking among pregnant women.

DESIGN

A prospective cohort study, starting in 2013.

SETTING

Andalusia, the south of Spain.

SAMPLE

A cohort of 486 healthy pregnant women followed-up on three occasions during pregnancy.

METHODS

Estimation of the proportions of women and partners who quit smoking at each trimester.

MAIN OUTCOME MEASURES

To determine factors associated in a multivariable model, considering sociodemographic, obstetric, anthropometric, lifestyle variables, and the smoking habits of their partners.

RESULTS

A high proportion of women quit smoking during pregnancy (61.08%; 95% confidence interval, 95% CI 53.61-68.55%). The smoking rate amongst mothers decreased from 36.06% (n = 167) before pregnancy to 14.08% (n = 65), 12.39% (n = 54), and 11.92% (n = 51) during the three pregnancy trimesters (P < 0.001), and consumption decreased from 8.71 cigarettes/day in the first trimester to 5.51 cigarettes/day in the second trimester (P < 0.001) and 5.96 cigarettes/day in third trimester (P = 0.0002 first versus third trimester). There was only a minimal decrease in the frequency of smoking among the partners, however: 38.44% (n = 178) before pregnancy, and 36.07% (n = 167), 32.72% (n = 143), and 31.85% (n = 136) during the three trimesters of pregnancy. The consumption of cigarettes did not decrease among partners: 11.75, 11.67, and 12.09 cigarettes/day (P = 0.4299 first versus second trimester; P = 0.654 first versus third trimester). Women whose partner smoked were less likely to quit (adjusted odds ratio, aOR 0.26; 95% CI 0.12-0.55).

CONCLUSIONS

About one in ten pregnant women smoked and one in four was a passive smoker. Strategies to reduce tobacco exposure in pregnancy should include a focus on partner smoking.

TWEETABLE ABSTRACT

Pregnant women quit smoking cigarettes in pregnancy. What about their partners?