A prospective cohort study of physical activity and time to pregnancy

Association between preconception body mass index and fertility in adult female: A systematic review and meta-analysis

Obesity potentially reduces fertility, but systematic reviews are lacking to summarize the existing literature. Therefore, we systematically summarized the association between preconception body mass index (BMI) and fertility in adult female based on existing reports. Up to September 2023, we conducted literature retrievals in different databases, including Web of Science, PubMed, Wiley, and ScienceDirect. Finally, 18 studies were included. Female with overweight/obesity (FOR = 0.85; 95% CI: 0.80, 0.90), obesity (FOR = 0.76; 95% CI: 0.69, 0.83), and overweight (FOR = 0.93; 95% CI: 0.88, 0.99) was associated with the significant time-to-pregnancy (TTP) prolongation (reduced fecundability). Interestingly, underweight was moderately associated with prolonged TTP in females (FOR = 0.95; 95% CI: 0.91, 0.99). Female overweight/obesity was associated with an increased risk of subfecundity (OR = 1.44; 95% CI: 1.20, 1.72) and infertility (OR = 1.60, 95% CI: 1.31-1.94). The findings emphasize the importance of considering appropriate preconception BMI at the population level for female fertility outcomes. In particular, prepregnancy obesity in females is strongly associated with prolonged TTP and increased risk of subfecundity. Scientific management of preconception BMI may improve fertility.

Interval training and cardiometabolic health in reproductive-aged females

Physical activity and exercise training are especially important for reproductive-aged females as exercise-induced health benefits can also affect their infants. However, levels of physical inactivity remain high among females in this age group, before, during, and after pregnancy. There is a great need for practical and feasible exercise modes to increase adherence to exercise in this population, and interval training may be a time-efficient training modality. Interval training is a form of exercise involving intermittent bouts of intense effort interspersed with recovery periods of rest or lower-intensity exercise. A substantial amount of research indicates that interval training induces superior cardiometabolic health benefits compared with iso-energetic moderate-intensity continuous exercise. This review provides a comprehensive overview of research on interval training interventions in reproductive-aged females across various life stages, focusing on the cardiometabolic health benefits. We discuss the potential role of interval training in premenopausal females with overweight/obesity, polycystic ovary syndrome, and subfertility, as well as the potential influence of oral contraceptives on cardiometabolic adaptations to interval training. Furthermore, this review also highlights recent findings supporting the beneficial role of high-intensity interval training for cardiometabolic health outcomes during pregnancy. In summary, the existing evidence suggests that interval training can improve several cardiometabolic and reproductive outcomes in females spanning different life stages. However, more research is needed to further strengthen the evidence-base for physical activity recommendations for females in their reproductive years of life.

PRO-FIT-CARE study: the feasibility assessment of a pilot online exercise intervention for persons living with obesity and female infertility

Introduction

Moderate-to-high physical activity participation is associated with a reduced risk of infertility. Yet, exercise interventions that target cardiorespiratory fitness, independent of weight loss, are lacking in obesity and female fertility research.

Purpose

The primary objective of the PRO-FIT-CARE (PROmoting FITness for CArdiometabolic & REproductive Health) study was to assess the feasibility of a moderate-to-high-intensity online exercise program for persons with obesity and female infertility.

Methods

Feasibility, safety, acceptability, and efficacy were assessed by examining: (1) recruitment and consent rate, (2) study retention, (3) adverse events, (4) participant satisfaction, (5) adherence, and (6) cardiorespiratory fitness.

Results

Eleven of thirty-two women contacted agreed to participate in the program (34.4% consent rate). Eight participants (72.7%) completed the study. One musculoskeletal injury was reported. There was a 30% adherence rate based on prescribed exercise intensity (60%-80% of heart rate maximum). One of eleven participants attended 80% of the exercise intervention. Based on a weekly satisfaction survey, the program had an overall high level of satisfaction. Compared to sex and age normative data, post-intervention, two of eight participants improved their cardiorespiratory fitness percentile rank.

Conclusion

The study highlights challenges with adherence to an online exercise program. While the program was safe and participants reported high levels of program satisfaction, approaches to improve adherence must be incorporated.

The influence of lifestyle interventions and overweight on infertility: a systematic review, meta-analysis, and meta-regression of randomized controlled trials

This study aimed to investigate the effect of lifestyle intervention (LSI) on diagnosed infertility in overweight and obese women. A systematic review and meta-analysis were conducted. A literature search was performed on the following databases from September 2022 to December 2022: PubMed, Web of Science, and SPORTDiscus. The inclusion criteria were the following: women between 18 and 45 years of age, BMI over 25.0 kg/m2, diagnosed with infertility, a weight loss intervention, and control group part of RCTs. In total, 15 studies were identified and included. The meta-analysis shows a beneficial effect of LSI on reducing weight, waist circumference, and BMI and increasing infertility. A significantly beneficial effect of lifestyle intervention on weight reduction was observed for participants who initially had a higher BMI, while a non-significant effect was observed for individuals with a BMI above 35 kg/m2. The meta-analysis showed a beneficial effect of lifestyle intervention on ovulation incidence and sex hormone-binding globulin. The lifestyle intervention group had 11.23 times more ovulatory incidence than the control group, which in turn increased the ability to conceive. As robust evidence for the effect of lifestyle interventions on infertility in obese and overweight women was found, it is advised to integrate similar interventions into future infertility treatment processes.

Association of Outdoor Physical Activity and Sports with Life Satisfaction among Women of Reproductive Age According to a European Representative Sample-A Longitudinal Analysis

(1) Background: Low life satisfaction (LS) is associated with impaired mental and physical health. Outdoor physical activity (PA) has diverse somatic and psychological benefits. This study aimed to analyse the associations between sports settings and LS in women of reproductive age. (2) Methods: Special Eurobarometer on Sport and Physical Activity (2022, 2018, 2013) data on regularity and settings of sports/PA, LS and sociodemographic variables were analysed. The representative sample consisted of 18,489 women (34.60 ± 9.36 years). Pearson χ2 test and multivariate logistic regression analysis were conducted, using IBM SPSS version 28.0 according to the STROBE guidelines. The significance level was set at p < 0.05. (3) There was a significant difference in LS based on sports settings (χ2 = 409.696, p < 0.001). In the outdoor group, a 21.4% higher probability of being "very satisfied" compared to the non-outdoor, 30.0% higher compared to the inactive group, was found (R2N = 0.151). Dividing the sample by age, a significant effect remained in middle adulthood (35-44 years p = 0.002 and 45-49 years p = 0.033). (4) Conclusions: Our results underline the importance of the promotion of outdoor, green exercise and the development of special interventions to maintain or improve the psychological well-being of women in reproductive age.

Activity Behaviors Before and During Pregnancy Are Associated With Women's Device-Measured Physical Activity and Sedentary Time in Later Parenthood: A Longitudinal Cohort Analysis

PURPOSE

To explore how activity behaviors before/during pregnancy relate to those in later parenthood, we assessed associations between sitting and moderate-/strenuous exercise before/during pregnancy, and sedentary time (SED) and moderate to vigorous physical activity (MVPA) 4-7 years postpartum ("later parenthood").

METHODS

Longitudinal data were from the Southampton Women's Survey, United Kingdom. Women reported time spent sitting (in hours per day), in moderate-strenuous exercise (hours per week), and in strenuous exercise (hours per week) at 3 time points before/during pregnancy (ie, preconception, at ∼12-wk and ∼34-wk gestation). From this, we derived 3 behavior trajectories for each woman. In later parenthood, women wore an accelerometer for ≤7 days (mean: 5.4 [SD: 1.8] d), which we used to derive 2 outcomes: minutes per day SED and in MVPA. Multilevel linear regression was used to explore associations between trajectories before/during pregnancy and device-measured SED/MVPA in later parenthood.

RESULTS

A total of 780 women provided valid data before/during pregnancy and in later parenthood. Consistent high sitters (vs low) were more sedentary 4-7 years postpartum (β = 39.5 min/d [95% confidence interval, 23.26 to 55.82]), as were women in groups who sat more in later pregnancy. Consistently high moderate/-strenuous exercisers (vs low) were 22% (95% confidence interval, 2%-47%) more active in later parenthood; those engaging in strenuous activity preconception tended to have higher MVPA as parents.

CONCLUSIONS

Trajectories of sitting and exercise before/during pregnancy are associated with SED and MVPA, respectively, in later parenthood. Interventions to reduce sitting in pregnancy and to encourage higher intensity activity preconception may benefit maternal and child health.

Mitochondrial dysfunction in the offspring of obese mothers and it's transmission through damaged oocyte mitochondria: Integration of mechanisms

In vivo and in vitro studies demonstrate that mitochondria in the oocyte, are susceptible to damage by suboptimal pre/pregnancy conditions, such as obesity. These suboptimal conditions have been shown to induce mitochondrial dysfunction (MD) in multiple tissues of the offspring, suggesting that mitochondria of oocytes that pass from mother to offspring, can carry information that can programme mitochondrial and metabolic dysfunction of the next generation. They also suggest that transmission of MD could increase the risk of obesity and other metabolic diseases in the population inter- and trans-generationally. In this review, we examined whether MD observed in offspring tissues of high energetic demand, is the result of the transmission of damaged mitochondria from obese mothers' oocytes to the offspring. The contribution of genome-independent mechanisms (namely mitophagy) in this transmission were also explored. Finally, potential interventions aimed at improving oocyte/embryo health were investigated, to see if they may provide an opportunity to halter the generational effects of MD.

Impact of Physical Activity and Sedentary Behavior on Spontaneous Female and Male Fertility: A Systematic Review

BACKGROUND

Before pregnancy is recognized, ovulation, fertilization, and implantation must all occur. Physical activity and sedentary behavior may impact pregnancy success by altering each or all of these processes. The aim of this review was to review the association between physical activity and sedentary behavior with spontaneous female and male fertility.

METHOD

PubMed/MEDLINE, Web of Science, CINAHL, SPORTDiscus, and Embase were searched from inception to August 9, 2021. Eligible studies included randomized controlled trials or observational studies, published in English, describing an association between physical activity or sedentary behavior (exposures) and spontaneous fertility (outcome) among women or men.

RESULTS

Thirty-four studies from 31 unique populations were included in this review (12 cross-sectional studies, 10 cohort studies, 6 case-control studies, 5 randomized controlled trials, and one case-cohort study). Of the 25 studies among women, the majority identified mixed results (n = 11) or no association (n = 9) between physical activity and female fertility. Seven studies reported on female fertility and sedentary behavior, and 2 found sedentary behavior was associated with decreased female fertility. Of the 11 studies among men, most of the studies (n = 6) found that physical activity was associated with increased male fertility. Two of the studies reported on male fertility and sedentary behavior, and neither identified an association.

CONCLUSIONS

The association between spontaneous fertility and physical activity in both men and women remains unclear, and the association with sedentary behavior remains largely unexplored.

Socioeconomic status and fecundability in a Danish preconception cohort

STUDY QUESTION

To what extent is socioeconomic status (SES), as measured by educational attainment and household income, associated with fecundability in a cohort of Danish couples trying to conceive?

SUMMARY ANSWER

In this preconception cohort, lower educational attainment and lower household income were associated with lower fecundability after adjusting for potential confounders.

WHAT IS KNOWN ALREADY

Approximately 15% of couples are affected by infertility. Socioeconomic disparities in health are well established. However, little is known about socioeconomic disparity and its relation to fertility.

STUDY DESIGN, SIZE, DURATION

This is a cohort study of Danish females aged 18-49 years who were trying to conceive between 2007 and 2021. Information was collected via baseline and bi-monthly follow-up questionnaires for 12 months or until reported pregnancy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Overall, 10 475 participants contributed 38 629 menstrual cycles and 6554 pregnancies during a maximum of 12 cycles of follow-up. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% CIs.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared with upper tertiary education (highest level), fecundability was substantially lower for primary and secondary school (FR: 0.73, 95% CI: 0.62-0.85), upper secondary school (FR: 0.89, 95% CI: 0.79-1.00), vocational education (FR: 0.81, 95% CI: 0.75-0.89), and lower tertiary education (FR: 0.87, 95% CI: 0.80-0.95), but not for middle tertiary education (FR: 0.98, 95% CI: 0.93-1.03). Compared with a monthly household income of >65 000 DKK, fecundability was lower for household income <25 000 DKK (FR: 0.78, 95% CI: 0.72-0.85), 25 000-39 000 DKK (FR: 0.88, 95% CI: 0.82-0.94), and 40 000-65 000 DKK (FR: 0.94, 95% CI: 0.88-0.99). The results did not change appreciably after adjustment for potential confounders.

LIMITATIONS, REASONS FOR CAUTION

We used educational attainment and household income as indicators of SES. However, SES is a complex concept, and these indicators may not reflect all aspects of SES. The study recruited couples planning to conceive, including the full spectrum of fertility from less fertile to highly fertile individuals. Our results may generalize to most couples who are trying to conceive.

WIDER IMPLICATIONS OF THE FINDINGS

Our results are consistent with the literature indicating well-documented inequities in health across socioeconomic groups. The associations for income were surprisingly strong considering the Danish welfare state. These results indicate that the redistributive welfare system in Denmark does not suffice to eradicate inequities in reproductive health.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, and the National Institute of Child Health and Human Development (RO1-HD086742, R21-HD050264, and R01-HD060680). The authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

The effect of physical activity on fertility: a mini-review

Although lifestyle factors such as diet, cigarette smoking, and alcohol consumption are increasingly recognized as important contributors to the risk of subfertility, the role of exercise in fertility remains less clear. As such, it is challenging for healthcare providers to deliver clear, evidence-based recommendations to patients regarding the optimal frequency and intensity with which they should exercise to maximize their chances of conception. Therefore, this review provides a critical overview of the available research for various patient populations.

Knowledge, attitudes, and practices toward exercises among women visiting an infertility clinic: A cross-sectional study

Globally, there is a rising prevalence of infertility, and it has a negative consequence on the quality of life of women. The researchers aimed to understand the knowledge, attitude, and practice of women with infertility toward exercises. A cross-sectional study was conducted on 332 women aged between 18 and 45 years attending an infertility clinic in a tertiary hospital in Southern India. Participants filled a self-developed, content validated, pilot-tested questionnaire. Informants perceived stress and weight gain to be the major causes of infertility. Exercise was believed to improve fertilization by 55.4% of the participants, and walking and yoga were the preferred mode of exercises.

Associations between Residential Greenspace and Fecundability in a North American Preconception Cohort Study

BACKGROUND

Residential green space can have positive physiological effects on human health through various mechanisms, including reducing stress and/or depression or facilitating physical activity. Although green space has been consistently associated with improved birth outcomes in several studies, there has been limited study of its effect on other reproductive outcomes, including fertility.

OBJECTIVE

We examined associations between residential green space and fecundability, the per-cycle probability of conception.

METHODS

We analyzed data from 8,563 female participants enrolled between 2013 and 2019 in Pregnancy Study Online (PRESTO), a prospective preconception cohort study of North American couples attempting conception. Participants completed a baseline questionnaire on sociodemographic, behavioral, and reproductive factors, and bimonthly follow-up questionnaires for up to 12 months to ascertain pregnancies. Using geocoded addresses, we calculated residential green space exposure using the Normalized Difference Vegetation Index (NDVI) within 50-, 100-, 250-, and 500 -m buffers across multiple temporal scales: annual maximum, seasonal maximum, and seasonal mean. We used proportional probabilities regression models to estimate fecundability ratios (FRs), adjusting for sociodemographic, behavioral, and neighborhood characteristics. We also evaluated the extent to which associations were mediated by reductions in perceived stress or depressive symptoms and increased physical activity.

RESULTS

When comparing the highest (≥ 0.8 ) with the lowest (< 0.2 ) NDVI exposures within 50 m , we observed positive associations in the annual maximum NDVI [FR: 1.33; 95% confidence interval (CI): 1.06, 1.67] and seasonal maximum NDVI (FR: 1.19; 95% CI: 1.00, 1.41) models, but little association in the seasonal mean NDVI models (FR: 0.98; 95% CI: 0.73, 1.30). Restricted cubic splines showed evidence of nonlinearity in this association. Results were similar across buffer distances. Perceived stress, depressive symptoms, and physical activity explained ≤ 5 : 0 % of mediation across all NDVI metrics.

DISCUSSION

In this cohort, greater residential green space was associated with a modest increase in fecundability. https://doi.org/10.1289/EHP10648.

Modifiable Risk Factor Score and Fecundability in a Preconception Cohort in Singapore

IMPORTANCE

Although multiple modifiable risk factors have been identified for reduced fecundability (defined as lower probability of conception within a menstrual cycle), no scoring system has been established to systematically evaluate fecundability among females who are attempting to conceive.

OBJECTIVE

To examine the association of a risk score based on 6 modifiable factors with fecundability, and to estimate the percentage reduction in incidence of nonconception if all study participants achieved a minimal risk score level.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study obtained data from the S-PRESTO (Singapore Preconception Study of Long-Term Maternal and Child Outcomes) prospective cohort study. Females of reproductive age who were trying to conceive were enrolled from February 2015 to October 2017 and followed for 1 year, ending in November 2018. Data were analyzed from March to May 2022.

EXPOSURES

A reduced fecundability risk score was derived by giving participants 1 point for each of the following factors: unhealthy body mass index, unhealthy diet, smoking, alcohol intake, folic acid supplement nonuser, and older maternal age. Total scores ranged from 0 to 6 and were classified into 5 levels: level 1 (score of 0 or 1), level 2 (score of 2), level 3 (score of 3), level 4 (score of 4), and level 5 (score of 5 or 6).

MAIN OUTCOMES AND MEASURES

Fecundability, measured by time to conception in cycles, was analyzed using discrete-time proportional hazards models with confounder adjustment.

RESULTS

A total of 937 females (mean [SD] age, 30.8 [3.8] years) were included, among whom 401 (42.8%) spontaneously conceived within 1 year of attempting conception; the median (IQR) number of cycles before conception was 4 (2-7). Compared with participants with a level 1 risk score, those with level 2, 3, 4, and 5 risk scores had reductions in fecundability of 31% (adjusted fecundability ratio [FR], 0.69; 95% CI, 0.54-0.88), 41% (FR, 0.59; 95% CI, 0.45-0.78), 54% (FR, 0.46; 95% CI, 0.31-0.69) and 77% (FR, 0.23; 95% CI, 0.07-0.73), respectively. Assessment of the population attributable fraction showed that all participants achieving a minimal (level 1) risk level would be associated with a reduction of 34% (95% CI, 30%-39%) in nonconception within a year.

CONCLUSIONS AND RELEVANCE

Results of this study revealed the co-occurrence of multiple modifiable risk factors for lowered fecundability and a substantially higher conception rate among participants with no or minimal risk factors. The risk assessment scoring system proposed is a simple and potentially useful public health tool for mitigating risks and guiding those who are trying to conceive.

Effects of physical activity and sleep duration on fertility: A systematic review and meta-analysis based on prospective cohort studies

Objective

Subfertility is a common problem for couples in modern society. Many studies have confirmed that lifestyle factors can affect fertility although there are conflicting conclusions relating to the effects of physical activity and sleep duration on fertility. In this study, we aimed to summarize and analyze the available evidence.

Methods

PubMed, Web of Science, Cochrane, and Embase databases (as of October 14, 2022) were systematically searched for eligible prospective cohort studies. Data were extracted and effect values were combined. We also performed methodological quality and bias risk assessments for all the included studies.

Results

A total of 10 eligible articles were included in our analysis; seven investigated the relationship between physical activity and fertility, and three investigated the effect of sleep duration on fertility. Compared with the lowest level of physical activity, high intensity physical activity (the highest levels of physical activity) was negatively correlated with fertility [odds ratio (OR) = 0.84; 95% confidence interval (CI): 0.70, 1.00, I ² = 64%]. However, we did not find an association between moderate intensity physical activity and fertility (OR = 1.09; 95% CI: 0.98, 1.22, I ² = 60%). We observed an inverse association between limited sleep duration (≤ 7 h) and fertility (OR = 0.92; 95% CI: 0.84, 1.00, I ² = 0%) compared with 8 h of sleep. The relationship between long sleep duration (≥9 h) and fertility was not statistically significant (OR = 0.85; 95% CI: 0.60, 1.21, I ² = 83%). According to the Newcastle-Ottawa Scale score, the overall quality of the research articles included was ranked as medium to high (6-9). Through GRADE system, the quality of evidence for the impact of high intensity physical activity and limited sleep duration on fertility was moderate, while the quality of evidence for the impact of moderate intensity physical activity and long sleep duration on fertility was low.

Conclusion

The current evidence shows that high intensity physical activity and limited sleep time are negatively related to fertility. But there was great heterogeneity among studies, and the quality of research evidence was low to median. Thus, further high-quality research is needed to confirm this conclusion.

PROSPERO registration number

CRD42022298137.

Obesity: A Doorway to a Molecular Path Leading to Infertility

The dramatic rise in obesity has recently made it a global health issue. About 1.9 billion were overweight, and 650 million global populations were obese in 2016. Obese women suffer longer conception time, lowered fertility rates, and greater rates of miscarriage. Obesity alters hormones such as adiponectin and leptin, affecting all levels within the hypothalamic-pituitary-gonadal axis. Advanced glycation end products (AGEs) and monocyte chemotactic protein-1 (MCP-1) are inflammatory cytokines that may play an important role in the pathophysiology of ovarian dysfunction in obesity. In obese males, there are altered sperm parameters, reduced testosterone, increased estradiol, hypogonadism, and epigenetic modifications transmitted to offspring. The focus of this article is on the possible adverse effects on reproductive health resulting from obesity and sheds light on different molecular pathways linking obesity with infertility in both female and male subjects. Electronic databases such as Google Scholar, Embase, Science Direct, PubMed, and Google Search Engine were utilized to find obesity and infertility-related papers. The search strategy is detailed in the method section. Even though multiple research work has shown that obesity impacts fertility in both male and female negatively, it is significant to perform extensive research on the molecular mechanisms that link obesity to infertility. This is to find therapeutics that may be developed aiming at these mechanisms to manage and prevent the negative effects of obesity on the reproductive system.

Habitual physical activity levels in women attending the one stop infertility clinic: A prospective cross-sectional observational study

Optimisation of lifestyle factors such as smoking and alcohol are encouraged to improve fecundability rates in the fertility setting. Currently, routine fertility consultations do not involve counselling or imparting advice regarding habitual physical activity (PA) and/or structured exercise, despite data showing that vigorous PA can be associated with delayed time to pregnancy. Therefore, this study aimed to determine habitual PA in a sample of women attending the one stop infertility (OSI) clinic. 250 women attending a large tertiary level NHS fertility unit prospectively anonymously completed a questionnaire over a period of 9 months. Participant's (mean age 34±5years, mean BMI 29±7kg/m2) habitual PA levels varied from vigorous exercise on ≥5 days/week (8%, n=17), to no moderate or high intensity activities across the whole week (66%, n=29). The majority of women reported no structured exercise (72%, n=179). No association was identified between any domain of PA and BMI, age, alcohol units, regular periods, or time spent trying to conceive (P > 0.05). Participant's habitual PA levels varied widely and no association between any domain of PA and background of the women was identified. No existing evidence and/or guidelines to explicitly inform women attempting to conceive regarding recommended PA levels are available, despite PA being a modifiable, affordable, and feasible lifestyle choice with the possible potential to improve fertility. A large-scale, clinical trial assessing effects of PA on fecundability is warranted to gain insights into the potential of this lifestyle factor to improve fertility outcomes and to explore the underlying biological mechanisms involved.

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.

Bovine In Vitro Oocyte Maturation and Embryo Production Used as a Model for Testing Endocrine Disrupting Chemicals Eliciting Female Reproductive Toxicity With Diethylstilbestrol as a Showcase Compound

Endocrine disrupting chemicals (EDCs) can interfere with normal hormonal action and regulation. Exposure of women to EDCs has been associated with adverse reproductive health outcomes. The assays currently used to identify EDCs that elicit female reproductive toxicity lack screening tests that address effects on the maturation of oocytes, a process that enables them to be fertilized and develop into embryos. Here, a screening method employing the bovine model of in vitro oocyte maturation and embryo production is described. Endpoints explored address important events in oocyte maturation and developmental competence acquisition. To test the method, the effects of the known human EDC diethylstilbestrol (DES; an estrogen receptor agonist) were evaluated in a range of concentrations (10^–9 M, 10^–7 M, 10^–5 M). Bovine oocytes were exposed to DES during in vitro maturation (IVM) or embryos were exposed during in vitro embryo culture (IVC). The endpoints evaluated included nuclear maturation, mitochondrial redistribution, cumulus cell expansion, apoptosis, and steroidogenesis. DES-exposed oocytes were fertilized to record embryo cleavage and blastocyst rates to uncover effects on developmental competence. Similarly, the development of embryos exposed to DES during IVC was monitored to assess the impact on early embryo development. Exposure to 10^–9 M or 10^–7 M DES did not affect the endpoints addressing oocyte maturation or embryo development. However, there were considerable detrimental effects observed in oocytes exposed to 10^–5 M DES. Specifically, compared to vehicle-treated oocytes, there was a statistically significant reduction in nuclear maturation (3% vs 84%), cumulus expansion (2.8-fold vs 3.6-fold) and blastocyst rate (3% vs 32%). Additionally, progesterone and pregnenolone concentrations measured in IVM culture media were increased. The screening method described here shows that bovine oocytes were sensitive to the action of this particular chemical (i.e., DES), albeit at high concentrations. In principle, this method provides a valuable tool to assess the oocyte maturation process and early embryo development that can be used for reproductive toxicity screening and possibly EDC identification. Further studies should include EDCs with different mechanisms of action and additional endpoints to further demonstrate the applicability of the bovine oocyte model for chemical risk assessment purposes and EDC identification.

Infertility in Men: Advances towards a Comprehensive and Integrative Strategy for Precision Theranostics

Male infertility is an increasing and serious medical concern, though the mechanism remains poorly understood. Impaired male reproductive function affects approximately half of infertile couples worldwide. Multiple factors related to the environment, genetics, age, and comorbidities have been associated with impaired sperm function. Present-day clinicians rely primarily on standard semen analysis to diagnose male reproductive potential and develop treatment strategies. To address sperm quality assessment bias and enhance analysis accuracy, the World Health Organization (WHO) has recommended standardized sperm testing; however, conventional diagnostic and therapeutic options for male infertility, including physical examination and semen standard analysis, remain ineffective in relieving the associated social burden. Instead, assisted reproductive techniques are becoming the primary therapeutic approach. In the post-genomic era, multiomics technologies that deeply interrogate the genome, transcriptome, proteome, and/or the epigenome, even at single-cell level, besides the breakthroughs in robotic surgery, stem cell therapy, and big data, offer promises towards solving semen quality deterioration and male factor infertility. This review highlights the complex etiology of male infertility, especially the roles of lifestyle and environmental factors, and discusses advanced technologies/methodologies used in characterizing its pathophysiology. A comprehensive combination of these innovative approaches in a global and multi-centric setting and fulfilling the suitable ethical consent could ensure optimal reproductive and developmental outcomes. These combinatorial approaches should allow for the development of diagnostic markers, molecular stratification classes, and personalized treatment strategies. Since lifestyle choices and environmental factors influence male fertility, their integration in any comprehensive approach is required for safe, proactive, cost-effective, and noninvasive precision male infertility theranostics that are affordable, accessible, and facilitate couples realizing their procreation dream.

Improving the health and treatment success rates of in vitro fertilization patients with traditional Chinese medicine: Need for more robust evidence and innovative approaches

Maximising access to and the success of fertility treatments should be a priority for global reproductive health, as should overall patient well-being. The demand for in vitro fertilization (IVF) and other assisted fertility treatments has increased over the past decade and is likely to further increase in years to come. Nevertheless, there is still considerable unmet demand for infertility support worldwide. Moreover, the high emotional, physical and financial burden experienced by individuals undergoing IVF cycles can be a risk for their mental and physical health, which in turn can influence treatment continuation and the likelihood of IVF success. Studies from various parts of the world show that most individuals undergoing IVF also use adjunct alternative medicines and procedures, the most common being traditional Chinese medicine (TCM). The complementary and synergistic role of TCM for individuals undergoing IVF is an area that merits further attention and research, both for its potential positive effects on IVF success rates and for its broader physical and mental health benefits. However, much of the existing evidence is not sufficiently robust or consistent for findings to be adopted with confidence. This commentary argues that much work must be done to understand the efficacy and clinical best practices for these integrated approaches. This can be achieved in part by developing more robust and clinically relevant randomized controlled trial protocols, collecting and triangulating evidence through a variety of study designs and methods, and strengthening the collection and pooling of clinic-level data.

The effect of short term exposure to outdoor air pollution on fertility

BACKGROUND

There is evidence to suggest that long term exposure to air pollution could be associated with decreased levels of fertility, although there is controversy as to how short term exposure may compromise fertility in IVF patients and what windows of exposure during the IVF process patients could be most vulnerable.

METHODS

This prospective cohort study aimed to evaluate the impact of acute exposure that air pollution have on reproductive outcomes in different moments of the IVF process. Women undergoing IVF living in Barcelona were recruited. Individual air pollution exposures were modelled at their home address 15 and 3 days before embryo transfer (15D and 3D, respectively), the same day of transfer (D0), and 7 days after (D7). The pollutants modelled were: PM2.5 [particulate matter (PM) ≤2.5 μm], PMcoarse (PM between 2.5 and 10μm), PM10 (PM≤10 μm), PM2.5 abs, and NO2 and NOx. Outcomes were analyzed using multi-level regression models, with adjustment for co-pollutants and confouding factors. Two sensitivity analyses were performed. First, the model was adjusted for subacute exposure (received 15 days before ET). The second analysis was based on the first transfer performed on each patient aiming to exclude patients who failed previous transfers.

RESULTS

One hundred ninety-four women were recruited, contributing with data for 486 embryo transfers. Acute and subacute exposure to PMs showed a tendency in increasing miscarriage rate and reducing clinical pregnancy rate, although results were not statistically significant. The first sensitivity analysis, showed a significant risk of miscarriage for PM2.5 exposure on 3D after adjusting for subacute exposure, and an increased risk of achieving no pregnancy for PM2.5, PMcoarse and PM10 on 3D. The second sensitivity analysis showed a significant risk of miscarriage for PM2.5 exposure on 3D, and a significant risk of achieving no pregnancy for PM2.5, PMcoarse and PM10 particularly on 3D. No association was observed for nitrogen dioxides on reproductive outcomes.

CONCLUSIONS

Exposure to particulate matter has a negative impact on reproductive outcomes in IVF patients. Subacute exposure seems to increase the harmful effect of the acute exposure on miscarriage and pregnancy rates. Nitrogen dioxides do not modify significantly the reproductive success.

Multicausal analysis on psychosocial and lifestyle factors among patients undergoing assisted reproductive therapy - with special regard to self-reported and objective measures of pre-treatment habitual physical activity

Background

National, regional and global trends in prevalence of infertility indicate its public health importance, however it effects various life dimensions of individuals and couples as well. Lifestyle habits may counteract with these factors. The aim of the study was the multicausal analysis of psychosocial and lifestyle factors undergoing assisted reproductive therapy (ART) with special regard to pre-treatment habitual physical activity (PA).

Methods

In a cross-sectional, observational cohort study on ART patients (N = 60, age 34.6 ± 5.2 years, BMI 24.2 ± 4.9 kg/m²) with follow up on outcome measures a detailed description was given on PA patterns (ActriGraph GT3X, GPAQ-H) and on general and infertility related distress (BDI-13, FPI).

Results

Respondents reported normal mood state (BDI-13) but moderately high infertility-related distress (FPI) in Social- and very high distress in Sexual Concern. It was revealed that time spent with recreational PA (RPA) could counteract with infertility-related distress (Social Concern R = -0.378, p = 0.013; Relationship Concern R = -0.365, p = 0.019).

In the presence of clinical pregnancy GPAQ-H RPA MET was significantly higher (p = 0.048), in the non-pregnant group cumulative values and work-related PA were higher. Correlations could be found between RPA time and the number of oocytes (R = 0.315, p = 0.045), matured oocytes (R = 0.339, p = 0.030) and embryos (R = 0.294, p = 0.062) by women who reached at least 150 min RPA (GPAQ-H). Multivariate linear regression revealed that the number of oocytes was positively influenced by the GPAQ-H recreation MET (R² = 0.367; F = 10.994, p = 0.004; B = 0.005, p = 0.004, B Constant = 4.604). Regarding the number of embryos (R² = 0.757, F = 17.692, p < 0.001, B Constant = 1.342) positive relationship was found with GPAQ-H RPA MET (B = 0.004, p < 0.001) and negative with BMI (B = -0.167, p = 0.038). It was disclosed (R² = 0.958, F = 408.479, p < 0.001) that higher Very Vigorous Activity (ActiGraph) was accompanied with higher hCG (B = 63.703, p ≤ 0.001). However, time spent with moderate PA (GPAQ-H) (B = 0.002, SE = 0.001, Wald = 3.944, p = 0.047, OR = 1.002) was significantly associated with live births.

Conclusions

Amount of PA alone did not have a positive effect on outcome of ART. Type and intensity seemed to be more significant. Existing differences in response to infertility due to recreational PA suggest the importance of the development of a specific intervention. The robust overestimation of PA in self-reports highlights the need to improve physical literacy of women undergoing ART.

Unraveling the Balance between Genes, Microbes, Lifestyle and the Environment to Improve Healthy Reproduction

Humans’ health is the result of a complex and balanced interplay between genetic factors, environmental stimuli, lifestyle habits, and the microbiota composition. The knowledge about their single contributions, as well as the complex network linking each to the others, is pivotal to understand the mechanisms underlying the onset of many diseases and can provide key information for their prevention, diagnosis and therapy. This applies also to reproduction. Reproduction, involving almost 10% of our genetic code, is one of the most critical human’s functions and is a key element to assess the well-being of a population. The last decades revealed a progressive decline of reproductive outcomes worldwide. As a consequence, there is a growing interest in unveiling the role of the different factors involved in human reproduction and great efforts have been carried out to improve its outcomes. As for many other diseases, it is now clear that the interplay between the underlying genetics, our commensal microbiome, the lifestyle habits and the environment we live in can either exacerbate the outcome or mitigate the adverse effects. Here, we aim to analyze how each of these factors contribute to reproduction highlighting their individual contribution and providing supporting evidence of how to modify their impact and overall contribution to a healthy reproductive status.

Physical and Sedentary Activities in Association with Reproductive Outcomes among Couples Seeking Infertility Treatment: A Prospective Cohort Study

BACKGROUND

The aim of this study was to investigate the association of physical activity (PA) with assisted reproductive technology (ART) treatment and pregnancy outcomes among couples seeking infertility treatment.

METHODS

This prospective cohort study was carried out among 128 infertile individuals (64 couples), entering the infertility clinic for ART procedures. Baseline PA (before entering any treatment) was assessed using accelerometry for both women and men. For every couple the infertility treatment outcomes were recorded.

RESULTS

The couples that required invasive ART procedures such as in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) spent less time in vigorous PA (-73 min/week per couple, woman + man) than those couples who became spontaneously pregnant after entering the study (p = 0.001). We observed no significant associations between the time spent in physical activities and positive pregnancy test or live birth.

CONCLUSIONS

Our results do not support a positive nor negative relation between the time the couples spent in physical activities and the chances of getting pregnant or having a baby among patients seeking infertility treatment. However, couples undergoing invasive ART procedures did less vigorous PA than couples that became spontaneously pregnant, suggesting that PA may interfere with their reproductive health.

Adiposity is associated with anovulation independent of serum free testosterone: A prospective cohort study

BACKGROUND

Obesity, a body mass index (BMI) ≥30 kg/m2 , is linked to infertility, potentially through a greater risk of anovulation due to elevated androgens. Yet, previous studies have not directly assessed the impact of adiposity, or body fat, on anovulation in the absence of clinical infertility.

OBJECTIVE

To characterise the associations between adiposity and anovulation among women menstruating on a regular basis.

METHODS

Women from the EAGeR trial (n = 1200), a randomised controlled trial of low-dose aspirin and pregnancy loss among women trying to conceive, were used to estimate associations between adiposity and incident anovulation. Participants completed baseline questionnaires and anthropometry, and provided blood specimens. Women used fertility monitors for up to six consecutive menstrual cycles, with collection of daily first morning voids for hormone analysis in the first two menstrual cycles for prospective assessment of anovulation. Anovulation was assessed by urine pregnanediol glucuronide or luteinising hormone concentration or the fertility monitor. Weighted mixed-effects log-binomial regression was used to estimate associations between measures of adiposity and incident anovulation, adjusted for free (bioavailable) testosterone, anti-Mullerian hormone (AMH), serum lipids, and demographic and life style factors.

RESULTS

343 (28.3%) women experienced at least one anovulatory cycle. Anovulation risk was higher per kg/m2 greater BMI (relative risk [RR] 1.03, 95% confidence interval (CI) 1.01, 1.04), cm waist circumference (RR 1.01, 95% CI 1.00, 1.02), mm subscapular skinfold (RR 1.02, 95% CI 1.01, 1.03), and mm middle upper arm circumference (RR 1.04, 95% CI 1.01, 1.06) adjusted for serum free testosterone, AMH, lipids, and other factors.

CONCLUSIONS

Adiposity may be associated with anovulation through pathways other than testosterone among regularly menstruating women. This may account in part for reported associations between greater adiposity and infertility among women having menstrual cycles regularly. Understanding the association between adiposity and anovulation might lead to targeted interventions for preventing infertility.

Does a Career in Orthopaedic Surgery Affect a Woman's Fertility?

BACKGROUND

Orthopaedic surgery lags behind other specialties in the recruitment of women. Concerns about fertility, pregnancy, and childbearing may be a deterrent to women when considering orthopaedic surgery as a specialty.

METHODS

An anonymous 168-item survey was distributed to the members of Ruth Jackson Orthopedic Society and the Women in Orthopaedics, an online group exclusive to female orthopaedic surgeons. Respondents were queried regarding family planning, contraceptive length of use, fertility, perinatal work habits, age and stage at each pregnancy, pregnancy complications, and miscarriages.

RESULTS

Eight hundred one surveys were collected. Seven hundred fifty (94%) expressed interest in having children of their own, with 60% having at least one child at the time of the survey. The average maternal age at birth of the first child was 33.6 ± 3.6 years. Voluntary childlessness was reported by 6% (49/801) of survey respondents. Eighteen percent of this group stated that their choice as an orthopaedic surgeon served as a barrier to having children. Among those with children, childbearing was intentionally delayed by 53% because of their career choice (425/801). Fifty-two percent did not conceive their first child until the end of their training. Complications during pregnancy were reported among 24%. A total of 853 children were conceived by this cohort with assisted reproductive technology being used 106 times. Miscarriages were reported by 38% (304/801). Of those who miscarried, only 28% informed their employer and 8% took time off during or immediately after their miscarriage.

CONCLUSION

Most respondents desire to have children but two-thirds delay doing so because of their career choice and its demands. Having a family is an important part of life for many orthopaedic surgeons, and our study provides an updated description of the fertility and pregnancy characteristics of female orthopaedic surgeons to help guide present and future surgeons in their family planning.

Practical Clinical and Diagnostic Pathway for the Investigation of the Infertile Couple

Capsule

This expert opinion summarizes current knowledge on risk factors for infertility and identifies a practical clinical and diagnostic approach for the male and female partners of an infertile couple aimed to improve the investigation and management of fertility problems.

Background

Infertility represents an important and growing health problem affecting up to 16% of couples worldwide. In most cases, male, female, or combined factor can be identified, and different causes or risk factors have been related to this condition. However, there are no standardized guidelines on the clinical-diagnostic approach of infertile couples and the recommendations concerning infertility are sometimes lacking, incomplete, or problematic to apply.

Objective

The aim of this work is to provide an appropriate clinical and diagnostic pathway for infertile couples designed by a multidisciplinary-team of experts. The rationale is based on the history and physical examination and then oriented on the basis of initial investigations. This approach could be applied in order to reduce variation in practice and to improve the investigation and management of fertility problems.

Methods

Prominent Italian experts of the main specialties committed in the ART procedures, including gynecologists, andrologists, embryologists, biologists, geneticists, oncologists, and microbiologists, called "InfertilItaly group", used available evidence to develop this expert position.

Outcomes

Starting from the individuation of the principal risk factors that may influence the fertility of females and males and both genders, the work group identified most appropriate procedures using a gradual approach to both partners aimed to obtain a precise diagnosis and the most effective therapeutic option, reducing invasive and occasionally redundant procedures.

Conclusions

This expert position provides current knowledge on risk factors and suggests a diagnostic workflow of infertile couples. By using this step-by-step approach, health care workers involved in ART, may individuate a practical clinical management of infertile couples shared by experts.

Effects of lifestyle factors on fertility: practical recommendations for modification

The role that lifestyle factors play in fertility issues has generated some amount of interest and questions among stakeholders. This review aims to highlight the impact of lifestyle behaviors on the fertility potential of an individual and what can be done to prevent or improve reproductive outcomes. Relevant published articles on the effect of lifestyle behaviors were obtained from Medline, Pubmed and Google scholar search engines for the study. The review of the literature indicates a negative impact of modifiable lifestyle factors such as fat-rich diets, delayed childbearing/age of starting family, smoking, alcohol misuse, sexual behavior, anxiety/depression and perception/beliefs were associated with fertility. The ensuing stress precipitates social behaviors such as excessive alcohol and caffeine consumption, tobacco smoking, misuse of recreational drugs/medications, which increases the risk of sexually transmitted diseases and infection leading to infertility. Practical recommendations to modify lifestyle behaviors and the impact of misconception of Assisted Reproductive Technology in the treatment of infertility are discussed. The need to make appropriate behavioral changes to stem the tide of infertility in Nigeria is imperative. More reproductive health education is needed to create the necessary awareness of the etiologies of infertility and the importance of in vitro fertilization treatment as a means of conceiving 'natural' babies is suggested.

LAY SUMMARY

Scientific evidence has suggested that modifiable lifestyle factors (consumption fat-rich diets, delayed childbearing/age of starting family, smoking, alcohol misuse, sexual behavior, anxiety/depression and perception/beliefs) play important roles in the general health and wellbeing of individuals including fertility. Evidence exists of an association between lifestyle behaviors and infertility in both men and women. Understanding the various processes through which modifiable lifestyle behaviors impair fertility will help to assist in the management of affected individuals. We conducted a comprehensive review of published studies to assess how lifestyle factors inhibit fertility and practical ways to ameliorate them. This review also deals with the misconception of Assisted Reproductive Technology in the treatment of infertility. The need to make appropriate behavioral changes to stem the tide of infertility in Nigeria is imperative. More reproductive health education is needed to create the necessary awareness of the causes of infertility and the importance of in vitro fertilization in the treatment of infertility.

The association of types, intensities and frequencies of physical activity with primary infertility among females in Gaza Strip, Palestine: A case-control study

INTRODUCTION

Physical activity and energy state balance have fundamentally been related to reproductive system and health. This study explored the relationship between different types, intensities and frequencies of physical activity with primary infertility among women in Gaza Strip, Palestine.

METHODS

A case-control study was conducted in Gaza Strip with the participation of 320 married couples. 160 infertile couples were chosen from five fertility centers registries from 2016 to 2018 and matched residentially with 160 fertile couples. Cases were selected through systematic stratified sampling of five lists categorized according to residency and the determined percentage selected from each list was proportional. Data were collected through a self-administered questionnaire extended by the short form of international physical activity questionnaire and analyzed through SPSS program version 22 by using descriptive analysis, independent T-test, cross-tabulation, and binary logistic regression.

RESULTS

Low frequency, intensity and duration of physical activity were associated with 3.1 risk of primary infertility (95% CI, 1.60-5.99, P < 0.001). Adjustment for age, marital age, age of menarche, refugee status and monthly income provided 3.2 risk (95% CI, 1.55-6.60, P = 0.002). Women spending more than 300 minutes a day sedentarily were 2.3 times more likely to have fertility problems than physically active females. Measuring energy expenditure in MET-min/w (Metabolic Equivalent) showed vigorous MET-min/w as negatively associated with the infertility status of females (Interquartile range IQR: 480 for cases and 720 for controls, P = 0.010). On the basis of energy expended in kilocalories in relation to weight, results showed the same association (IQR: 564 for case and 864 for controls, P = 0.011). No associations were found between moderate activity levels and primary infertility.

CONCLUSION

Low levels of physical activity and sedentary lifestyle endanger the fertility status of females in Gaza Strip. This may offer the need for endorsing and formalizing adequate physical activity education and awareness protocols in the national reproductive health guidelines and empowering environmental capacity building to alter physical activity-related cultural norms.

Infertility and physical activity: A cross-sectional study of women living in Yazd aged 20-49 yr, 2014-2015

Background

Changes in the state of energy balance owing to changes in physical activity (PA) may affect the reproductive system.

Objective

the aim of this study was to assess the association between PA and infertility of women living in Yazd 2014 - 2015.

Materials and Methods

The study method was analytical cross-sectional on the Yazd Health Study (YaHS) data which was conducted on 10,000 people. We studied 2,611 women (20 and 49 yrs old), living in Greater Yazd area. PA information was collected using a physical activity questionnaire (IPAQ) short form. The standardized instruments were used for anthropometrics measurement.

Results

Totally 135 cases of infertility were documented. The overall prevalence of infertility was 4.73% (95% CI: 3.94-5.59%). The median of PA scores (METs) in women was 746.66 and 25-75% interquartile range was 361.25-1277.25. The relationship according to the Chi-square test between infertility and PA, as categorized variables, was significant (p = 0.015). It showed over 90% of those who suffered from infertility had a low or moderate PA.

Conclusion

The results of our study showed that there is a significant relationship between infertility and PA level in women living in Greater Yazd area. Also, women with infertility had lower activity levels, consistent with most previous studies.

Women's age and total motile normal morphology sperm count predict fecundability: a prospective cohort study

OBJECTIVE

This study investigated the role of women's age, serum anti-Müllerian hormone (AMH) level and semen parameters in predicting fecundability.

METHODS

This was a prospective cohort study on couples attending for preconceptional health check. Occurrence of conception at 1 year after ceasing contraception and time to pregnancy were noted by telephone follow-up. The women's age, serum AMH level and total motile normal morphology sperm count (TMNC) were compared between those who conceived and those who did not after 1 year; their independent predictive value on conception at 1 year was analysed by logistic regression. Among those conceiving within 1 year, Spearman's correlations between time to pregnancy and the clinical parameters were studied.

RESULTS

Of the 100 couples analysed, we found younger age of the women (p=0.008), higher serum AMH level (p=0.038) and higher TMNC (p=0.015) in those that conceived within 1 year. Multivariate logistic regression found that women's age (OR 0.867, 95% CI 0.761 to 0.988, p=0.032) and TMNC (OR 1.089, 95% 1.001-1.185, p=0.047), but not serum AMH level, significantly predicted conception within 1 year. Among those that conceived within 1 year, none of the parameters analysed were correlated with time to pregnancy within 1 year.

CONCLUSIONS

Women's age and TNMC are significant independent predictors of conception within 1 year. No parameter was shown to predict the time to pregnancy within 1 year. This finding can aid preconceptional counselling of couples who are planning for pregnancy.

Physical Activity and Body Mass Index in Relation to Infertility in Women

BACKGROUND

Infertility is a global social issue, and reproductive health is a priority in global health. This review aimed to study the relation between physical activity (PA) and infertility in non-obese or non-overweight women.

METHODS

We used search strategies in the National Library of Medicine database including the PubMed database to October 2019 to find articles related to women and fertility, infertility, exercise, PA, pregnancy rate, live births, fecundability, and conception. Only cohort studies or randomized controlled trials in English were chosen for review that included outcomes directly related to becoming pregnant. We selected studies in which the participants were categorized by low or high body mass index (BMI).

RESULTS

We found 6 papers meeting our criteria. In the association between PA and outcome, vigorous PA in women with low BMI resulted in both positive and negative effects that were weaker than those in women with high BMI. Among women with low BMI, moderate PA was weakly but positively associated with outcome whereas walking was not.

CONCLUSION

We observed some trends and a slight difference between the outcomes of women with low versus high BMI. There are only a few studies on infertile women with low BMI, and further investigation is warranted.

Changes in Behavior with Increasing Pregnancy Attempt Time: A Prospective Cohort Study

BACKGROUND

The extent to which couples change their behaviors with increasing pregnancy attempt time is not well documented.

METHODS

We examined change in selected behaviors over pregnancy attempt time in a North American preconception cohort study. Eligible females were ages 21-45 years and not using fertility treatment. Participants completed baseline and bimonthly follow-up questionnaires for up to 12 months or until pregnancy.

RESULTS

Among 3,339 females attempting pregnancy for 0-1 cycles at enrollment, 250 contributed 12 months of follow-up without conceiving. Comparing behaviors at 12 months versus baseline, weighted for loss-to-follow-up, we observed small-to-moderate reductions in mean caffeine intake (-19.5 mg/day, CI = -32.7, -6.37), alcohol intake (-0.85 drinks/week, CI = -1.28, -0.43), marijuana use (-3.89 percentage points, CI = -7.33, 0.46), and vigorous exercise (-0.68 hours/week, CI = -1.05, -0.31), and a large increase in activities to improve conception chances (e.g., ovulation testing) (21.7 percentage points, CI = 14.8, 28.6). There was little change in mean cigarette smoking (-0.27 percentage points, CI = -1.58, 1.04), perceived stress scale score (-0.04 units, CI = -0.77, 0.69), or other factors (e.g., sugar-sweetened soda intake, moderate exercise, intercourse frequency, and multivitamin use), but some heterogeneity within subgroups (e.g., 31% increased and 32% decreased their perceived stress scores by ≥2 units; 14% reduced their smoking but none increased their smoking by ≥5 cigarettes/day).

CONCLUSIONS

Although many behaviors changed with increasing pregnancy attempt time, mean changes tended to be modest for most variables. The largest differences were observed for the use of caffeine, alcohol, and marijuana, and methods to improve conception chances.

Maternal physical activity and sedentary behaviour before and during in vitro fertilization treatment: a longitudinal study exploring the associations with controlled ovarian stimulation and pregnancy outcomes

PURPOSE

To evaluate the association of objectively measured physical activity (PA) and sedentary behaviour before and during in vitro fertilization (IVF) with controlled ovarian stimulation (COS) and pregnancy outcomes.

METHODS

This longitudinal study involved 107 infertile women undergoing IVF treatment. PA and sedentary behaviour were measured for 14 consecutive days using accelerometry as follows: (1) before IVF treatment, (2) during IVF at the implantation time, immediately after embryo transfer, and (3) after positive pregnancy test. Total screen time was assessed by questionnaires. COS results were measured as the number of oocytes and embryos obtained, and the study outcomes included positive hCG, clinical pregnancy, and live birth.

RESULTS

Compared with baseline activity levels, women significantly reduced their PA and increased sedentary behaviour during IVF (p ≤ 0.001). Higher average PA, light PA, and ratio between breaks in every ≥ 30-min blocks of sedentary time showed positive associations, while sedentary time, number, and time accumulated in blocks of ≥ 30 min of sedentary time associated negatively with oocyte and embryo counts (all p < 0.05). Women with high total screen time during non-work days (≥ 7 h) obtained 4.7 oocytes (p = 0.005) and 2.8 embryos (p = 0.008) less in COS. PA and sedentary behaviour before and during IVF did not affect the positive hCG, clinical pregnancy, and live birth outcomes.

CONCLUSION

Our study results suggest that higher time spent in PA and lower time spent in sedentary behaviour before entering assisted reproduction is associated with better COS outcomes, while activity levels before and during IVF do not affect the implantation, pregnancy, and live birth outcomes.

C-reactive protein and ART outcomes: a systematic review

BACKGROUND

A dynamic balance between pro- and anti-inflammatory factors contributes to regulating human female reproduction. Chronic low-grade inflammation has been detected in several female reproductive conditions, from anovulation to embryo implantation failure. C-reactive protein (CRP) is a reliable marker of inflammation that is extensively used in clinical practice. Recent studies quantified CRP in the serum of infertile women undergoing ART and suggested its potential for the prediction of ART reproductive outcomes.

OBJECTIVE AND RATIONALE

The first objective of this systematic review of the available literature was to evaluate the association between pre-implantation circulating CRP concentration and pregnancy rates in women undergoing ART. The second objective was to describe serum CRP concentration changes after early embryo implantation. The changes in circulating CRP throughout the ART cycle, clinical implications of CRP quantification for the management of women undergoing ART, and future therapeutic options will also be discussed.

SEARCH METHODS

The MEDLINE database was systematically searched from inception to March 2019 using the following key words: (C-reactive protein) AND (assisted reproductive techniques OR ovulation induction OR insemination OR in vitro fertilization). Only articles in English were considered. Studies were selected based on title and abstract. The full text of potentially relevant articles was retrieved and assessed for inclusion by two reviewers (S.B. and S.H.). The protocol was registered in the International prospective register of systematic reviews (PROSPERO; registration number: CRD148687).

OUTCOMES

In total, 10 studies were included in this systematic review. Most of these studies reported lower circulating CRP values before the window of implantation and higher circulating CRP values during the peri-implantation period in women with successful ART outcome (biochemical or clinical pregnancy) compared to women without a successful outcome. Several lifestyle factors and/or drugs that reduce the concentration of circulating CRP significantly improve ART outcomes. Subgroup analyses according to female BMI and baseline circulating CRP concentration are highly recommended in future analyses.

WIDER IMPLICATIONS

These findings highlight a possible detrimental impact of preconception high circulating CRP concentration on ART outcomes. However, the biochemical or clinical pregnancy rate endpoints used in the studies examined here are insufficient (there were no data on live birth outcome), and the impact of major variables that can influence CRP and/or ART, for example maternal age, BMI, number of transferred embryos, and use of anti-inflammatory drugs, were not considered in the analyses. CRP quantification may be a potential marker of ART outcome, but its predictive value still needs to be investigated in large prospective studies. In future, the quantification of circulating CRP before starting ART could help to identify patients with a poor ART prognosis, leading to ART cycle cancellation or to preconception treatment to minimize the medical risks and costs.

Determining the association between physical activity prior to conception and pregnancy rate: A systematic review and meta-analysis of prospective cohort studies

We investigated the association between physical activity (PA) before pregnancy and pregnancy rate according to intensity and amount of exercise. Eleven prospective cohort studies were included in this meta-analysis. Any amount of moderate-intensity PA was associated with a statistically higher rate of pregnancy compared to that in patients with no PA (p < .05). Any amount of vigorous PA was associated with decreased pregnancy rate; regular PA was associated with decreased infertility (p > .05). In contrast, vigorous PA was associated with increased infertility (p > .05). Therefore, women who are preparing for pregnancy are recommended to perform regular, moderate-intensity PA.

Observational Study of the Social Determinants of Health in Subfertile versus Nonsubfertile Women

CONTEXT

Subfertility affects about 15% of couples worldwide. There are several factors that affect subfertility called social determinants of health (SDH): biological factors as age, ethnic origin, and body mass index; behavioral factors as alcohol intake, smoking, coffee, dietary restriction, physical activity, and psychological state; and contextual factors as education, work activity, and income level.

AIMS

The aim of the study is to evaluate the distribution's relevance of the SDH in subfertile women versus nonsubfertile women.

SETTINGS AND DESIGN

A prospective comparative study with two groups of women recruited over 1 year at hospital consultation: one group with subfertile women excluding women without a male partner or with a previous child and another one formed by primigravidae, excluding those receiving assisted reproduction techniques to become pregnant.

SUBJECTS AND METHODS

We compare the different factors between subfertile and nonsubfertile women one by one. Second, a multivariate analysis was conducted with logistic regression. In all cases, informed consent was obtained.

RESULTS

Regular physical exercise 3-4 times/week (odds ratio [OR]: 0.33, 95% confidence interval [CI]: 0.15-0.71) or healthy food products such as fish 1-2 times/week (OR: 0.40, 95% CI: 0.17-0.95) were associated with nonsubfertile women.

CONCLUSIONS

The distribution of SDH in natural fertility is not altogether homogeneous. Weight control by means of restricting calorie intake, greater consumption of healthy foods such as fish, regular physical exercise, and lower age are positively associated with fertility. Population-level intervention is possible to improve women's health, as these are modifiable factors. Ethnic origin can be considered as a relevant factor, as it may condition the distribution of other determinants.

Sedentary behavior, physical inactivity and body composition in relation to idiopathic infertility among men and women

BACKGROUND

Physical activity (PA) and sedentary behavior have inconsistent effects on fertility. High body mass index is associated with infertility but to our knowledge, very few studies have explored body composition in association to fertility.

OBJECTIVE

To assess the association between physical inactivity, sedentary behavior, body composition and idiopathic infertility in French men and women.

DESIGN

We conducted a case-control multicentric observational study. 159 infertile (79 men and 80 women) and 143 fertile (72 men and 71 women) were recorded in four fertility centers.

MAIN OUTCOME MEASURES

Participants completed self-administered questionnaires on sociodemographic and lifestyle characteristics, dietary intake, physical activity and sedentary behavior. Anthropometrics were measured, and bioelectrical impedance analysis was used to estimate body composition. Multivariable logistic regression was used to analyze the association of fertility with PA level and sedentary behavior.

RESULTS

In men, being physically inactive (Odd ratio [OR] 2.20; 95% confidence interval [CI], 1.06, 4.58) and having fat mass greater than the reference values for their age (OR 2.83; 95%CI, 1.31, 6.10) were positively associated with infertility. Sedentary behavior and fat-free mass were not related to infertility in men. In women, sedentary behavior (OR 3.61; 95%CI, 1.58, 8.24), high body fat (OR 3.16; 95%CI, 1.36, 7.37) and low fat-free mass (OR 2.65; 95%CI, 1.10, 6.37) were associated with infertility. PA level was not associated with fertility in women.

CONCLUSIONS

This study suggests that sedentary behavior and physical inactivity would represent two independent risk factors associated with infertility. The various elements that make up physical activity (frequency, intensity, time, and type of exercise) and the interrupting time spent sitting should be considered. Body composition variation should be explored further in relation to the biological pathways involved in idiopathic infertility. Moreover, the improvement of lifestyle factors should be considered in infertility treatment.

A prospective study of physical activity and fecundability in women with a history of pregnancy loss

STUDY QUESTION

Is physical activity (PA) associated with fecundability in women with a history of prior pregnancy loss?

SUMMARY ANSWER

Higher fecundability was related to walking among overweight/obese women and to vigorous PA in women overall.

WHAT IS KNOWN ALREADY

PA may influence fecundability through altered endocrine function. Studies evaluating this association have primarily utilized Internet-based recruitment and self-report for pregnancy assessment and have yielded conflicting results.

STUDY DESIGN, SIZE, DURATION

This is a secondary analysis of the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial (2007-2011), a multisite, randomized controlled trial of preconception-initiated low-dose aspirin.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Healthy women (n = 1214), aged 18-40 and with 1-2 prior pregnancy losses, were recruited from four US medical centers. Participants were followed for up to six menstrual cycles while attempting pregnancy and through pregnancy for those who became pregnant. Time to hCG detected pregnancy was assessed using discrete-time Cox proportional hazard models to estimate fecundability odds ratios (FOR) adjusted for covariates, accounting for left truncation and right censoring.

MAIN RESULTS AND THE ROLE OF CHANCE

The association of walking with fecundability varied significantly by BMI (P-interaction = 0.01). Among overweight/obese women, walking ≥10 min at a time was related to improved fecundability (FOR = 1.82, 95% CI: 1.19, 2.77). In adjusted models, women reporting >4 h/wk of vigorous activity had significantly higher fecundability (FOR = 1.69, 95% CI: 1.24, 2.31) compared to no vigorous activity. Associations of vigorous activity with fecundability were not significantly different by BMI (P-interaction = 0.9). Moderate activity, sitting, and International Physical Activity Questionnaire (IPAQ) categories were not associated with fecundability overall or in BMI-stratified analyses.

LIMITATIONS, REASONS FOR CAUTION

Some misclassification of PA levels as determined by the short form of the IPAQ is likely to have occurred, and may have led to non-differential misclassification of exposure in our study. Information on diet and change in BMI was not collected and may have contributed to some residual confounding in our results. The generalizability of our results may be limited as our population consisted of women with a history of one or two pregnancy losses.

WIDER IMPLICATIONS OF THE FINDINGS

These findings provide positive evidence for the benefits of PA in women attempting pregnancy, especially for walking among those with higher BMI. Further study is necessary to clarify possible mechanisms through which walking and vigorous activity might affect time-to-pregnancy.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The authors report no conflicts of interest in this work.

TRIAL REGISTRATION NUMBER

#NCT00467363.

Fecundability among Danish women with a history of miscarriage: a prospective cohort study

OBJECTIVE

To examine the association between history of miscarriage and fecundability (the cycle-specific probability of conception).

DESIGN

Nationwide prospective cohort study using web-based questionnaires.

SETTING

Denmark, 2007-2012.

PARTICIPANTS

977 women attempting to conceive, not using fertility treatment, and with a reproductive history of only miscarriage or only live birth.

EXPOSURE AND OUTCOME MEASURES

Information on previous pregnancy outcomes, including miscarriage, came from self-report or from relevant registries. Participants were followed for up to 12 months or until they reported a pregnancy, stopped trying to conceive or started fertility treatment, whichever came first. We used Kaplan-Meier methods to estimate cumulative probabilities of conception for women whose reproductive history included only miscarriage or only live birth. Using proportional probabilities regression modelling, we computed fecundability ratios (FR) with 95% CI comparing women with a history of only miscarriage with women with a history of only live birth.

RESULTS

After adjustment for potential confounders, the cumulative probabilities of conception within 12 cycles of follow-up were 85% (95% CI 81% to 89%) for women with a history of 1 miscarriage, 85% (95% CI 73% to 92%) for women with a history of ≥2 miscarriages and 88% (95% CI 87% to 89%) for women whose reproductive history included only live birth. Adjusted FRs were 0.87 (95% CI 0.71 to 1.07) and 0.65 (95% CI 0.36 to 1.17) for women with a history of 1 and ≥2 miscarriages, respectively.

CONCLUSIONS

Our results indicate that women with a history of miscarriage may have slightly reduced fecundability compared with women with a history of only live birth. The reduction in fecundability was greater for women with repeated miscarriages, although the estimates were imprecise. Despite a potential delay in conception, women with previous miscarriage may have similar probability of pregnancy by 12 cycles of attempts to women with proven fertility.

Declining Fertility with Reproductive Aging: How to Protect Your Patient's Fertility by Knowing the Milestones

Protection of fertility shares many of the same concepts as optimization of general health, such as smoking cessation, maintenance of a healthy body weight, and moderation of alcohol intake. Increasing attention has been placed on minimizing exposures to known reproductive toxicants. There are few conclusive data to support specific diet patterns or supplements for fertility. Ovarian reserve testing has been explored as potential diagnostic tests for assessment of reproductive aging with some controversy. Finally, the development of vitrification in the assisted reproduction laboratory has increased the success and, therefore, access to fertility preservation by way of oocyte or embryo cryopreservation.

The menstrual cycle associated with insomnia in newly employed nurses performing shift work: a 12-month follow-up study

PURPOSE

This study aimed to investigate whether insomnia among newly-employed shift-working nurses is associated with menstrual cycle irregularity.

METHODS

We followed 287 nurses employed between 2015 and 2016 for 12 months. An Insomnia Severity Index (ISI) was completed to determine levels of insomnia 6 months after beginning work. At baseline and at 12-month follow-up, menstrual cycle information was obtained using clinical interviews. We analyzed baseline data separately by prevalence (participants with menstrual irregularity, n = 287) and incidence (participants with no reported menstrual irregularity, n = 238).

RESULTS

In a multivariate logistic regression analysis, including age, body mass index, and physical activity, insomnia was associated with a 2.05-fold increase in the odds of newly developing menstrual cycle irregularity compared with not having insomnia [odds ratio (OR) 2.05, 95% confidence interval (CI) 1.12-3.77]. Insomnia was associated with a 3.05-fold increase in the prevalence of menstrual cycle irregularity compared with not having insomnia (OR 3.05, 95% CI 1.81-5.13). As the ISI score increased, both the incidence and prevalence odds of menstrual cycle irregularity tended to increase.

CONCLUSIONS

Insomnia can induce menstrual cycle irregularity among nurses working shifts, and insomnia may have an important role in the pathway from shift work to menstrual dysfunction, aside from the possible effects of circadian rhythm disruption.

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.

Effect of Exercise on Ovulation: A Systematic Review

BACKGROUND

Infertility has been described as a devastating life crisis for couples, and has a particularly severe effect on women, in terms of anxiety and depression. Anovulation accounts for around 30% of female infertility, and while lifestyle factors such as physical activity are known to be important, the relationship between exercise and ovulation is multi-factorial and complex, and to date there are no clear recommendations concerning exercise regimes.

OBJECTIVES

The objective of this review was to systematically assess the effect of physical activity on ovulation and to discuss the possible mechanisms by which exercise acts to modulate ovulation in reproductive-age women. This was done with a view to improve existing guidelines for women wishing to conceive, as well as women suffering from anovulatory infertility.

SEARCH METHODS

The published literature was searched up to April 2016 using the search terms ovulation, anovulatory, fertility, sport, physical activity and exercise. Both observational and interventional studies were considered, as well as studies that combined exercise with diet. Case studies and articles that did not report anovulation/ovulation or ovarian morphology as outcomes were excluded. Studies involving administered drugs in addition to exercise were excluded.

RESULTS

In total, ten interventions and four observational cohort studies were deemed relevant. Cohort studies showed that there is an increased risk of anovulation in extremely heavy exercisers (>60 min/day), but vigorous exercise of 30-60 min/day was associated with reduced risk of anovulatory infertility. Ten interventions were identified, and of these three have studied the effect of vigorous exercise on ovulation in healthy, ovulating women, but only one showed a significant disruption of ovulation as a result. Seven studies have investigated the effect of exercise on overweight/obese women suffering from polycystic ovary syndrome (PCOS) or anovulatory infertility, showing that exercise, with or without diet, can lead to resumption of ovulation. The mechanism by which exercise affects ovulation is most probably via modulation of the hypothalamic-pituitary-gonadal (HPG) axis due to increased activity of the hypothalamic-pituitary-adrenal (HPA) axis. In heavy exercisers and/or underweight women, an energy drain, low leptin and fluctuating opioids caused by excess exercise have been implicated in HPA dysfunction. In overweight and obese women (with or without PCOS), exercise contributed to lower insulin and free androgen levels, leading to the restoration of HPA regulation of ovulation.

CONCLUSIONS

Several clear gaps have been identified in the existing literature. Short-term studies of over-training have not always produced the disturbance to ovulation identified in the observational studies, bringing up the question of the roles of longer term training and chronic energy deficit. We believe this merits further investigation in specific cohorts, such as professional athletes. Another gap is the complete absence of exercise-based interventions in anovulatory women with a normal body mass index (BMI). The possibly unjustified focus on weight loss rather than the exercise programme means there is also a lack of studies comparing types of physical activity, intensity and settings. We believe that these gaps are delaying an efficient and effective use of exercise as a therapeutic modality to treat anovulatory infertility.

Maternal physical activity before IVF/ICSI cycles improves clinical pregnancy rate and live birth rate: a systematic review and meta-analysis

OBJECTIVE

This meta-analysis was aimed to evaluate the association between maternal physical activity before IVF/ICSI cycles and reproductive outcomes.

METHODS

We searched databases of PubMed, EMBASE and Web of Science electronic databases, and ongoing trials up to November 2017 to identify studies that focused on the relationship between maternal physical activity before IVF/ICSI cycles and reproductive outcomes, including implantation rate, clinical pregnancy rate, miscarriage rate and live birth rate. Odds ratio (OR) with 95% confidence intervals, were calculated to assess the results of each outcome.

RESULTS

Eight published studies encompassing 3683 infertile couples undergoing IVF/ICSI treatment were included into the analysis. There was an increasing, but not statistically significant, trend in implantation rate for physically active women when compared with physically inactive women (OR = 1.95, 95% CI 0.99-3.83, I2 = 77%). No significant difference was found in miscarriage rate between physically active women and physically inactive women (OR = 0.76, 95% CI 0.41-1.44, I2 = 49%). However, rates of clinical pregnancy and live births in physically active women were significantly higher than those in physically inactive women (OR = 1.96, 95% CI 1.40, 2.73, I2 = 42% and OR = 1.95, 95% CI 1.06-3.59, I2 = 82%, respectively). Subgroup analysis helped to confirm these results.

CONCLUSIONS

Female physical activity before IVF/ICSI cycles was associated with increased rates of clinical pregnancy and live births, whereas only a small but not statistically significant increase was found in implantation rate, and no effect was shown on miscarriage rate.