Outdoor air pollution and diminished ovarian reserve among infertile Korean women

Associations of long-term exposure to fine particulate matter and its components with ovarian aging: Evidence from a cross-sectional study in China

This study aimed to investigate associations between long-term exposure to PM2.5, or its constituents, and ovarian aging, assessed by age at natural menopause (ANM) and early menopause (EM) prevalence. A total of 15,345 postmenopausal women were recruited from an epidemiologic survey conducted across 12 provinces in China (2023-2024). Concentrations of air pollutants [PM2.5 mass, sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), organic matter (OM), and black carbon (BC)] were obtained from the Tracking Air Pollution in China database. Multivariable regression models with random effects and quantile g-computation models were used to evaluate associations. Each interquartile range increase in 5-year average concentrations of PM2.5, SO42-, NO3-, NH4+, OM, or BC were correlated with significant changes of -0.79 (95 %CI: -0.87, -0.72), -0.98 (95 %CI: -1.06, -0.90), -0.54 (95 %CI: -0.63, -0.45), -0.90 (95 %CI: -0.98, -0.81), -0.83 (95 %CI: -0.91, -0.76), and -1.02 (95 %CI: -1.09, -0.96) in ANM, respectively. Joint exposure analysis revealed that the five combined PM2.5 constituents shared a negative association with ANM in which BC provided the largest weight. These pollutants were also significantly associated with elevated EM prevalence, wherein BC provided the strongest contribution. The associations were stronger in women with a history of smoking, other hazardous environmental exposure, and lower education level.

Fine particulate matter components and reproductive hormones in female adults: A 15-year longitudinal cohort study

BACKGROUND

Few cohort studies have evaluated the long-term impacts of ambient fine particulate matter (PM2.5) and its components on reproductive hormone levels in female adults.

METHODS

We conducted a 15-year retrospective cohort study in Taiwan between 2003 and 2017. The two-year average concentrations of PM2.5 and its components, including sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), organic matter (OM), and black carbon (BC), were assessed at each participant's addresses. Linear mixed models were used to examine the associations of PM2.5 and its components with reproductive hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), estradiol (E2), and prolactin (PRL). Stratified analyses were conducted to identify vulnerable populations.

RESULTS

17,152 female adults were included. Each interquartile range (IQR: 3.545 μg/m3) increase in PM2.5 was associated with a 0.585 mIU/mL [95% confidence interval (CI): 0.190-0.980] increase in FSH levels. Among the five components of PM2.5, BC had the strongest positive association [each IQR (0.272 μg/m3) increase was associated with a 0.863 mIU/mL (95% CI: 0.476-1.250) increase in FSH levels], followed by OM, SO42-, and NH4+. Similar associations were found for LH, with a 0.483 mIU/mL (95% CI: 0.225-0.742) and 0.684 mIU/mL (95% CI: 0.431-0.938) increase in LH levels per IQR increase in PM2.5 and BC, respectively. The pollutants were marginally associated with decreased E2 levels and increased PRL levels. Non-linear associations between PM2.5 and its components and the levels of FSH, LH, E2, and PRL were observed. These pollutants were also positively associated with T levels among young adults. Post-menopausal women were more susceptible to the chronic impacts of PM2.5 and its components.

CONCLUSION

Our study highlighted the adverse impacts of long-term exposure to PM2.5 components on hormonal homeostasis, revealing the biological mechanism of air pollution-reproductive health associations in females. Implementing stringent control of air pollution levels can benefit reproductive health in female adults, even in moderately polluted regions.

Environmental pollution and human fertility: investigating the relationship between PM2.5 exposure and assisted reproductive technology outcomes

OBJECTIVE

To investigate the impact of seasonal variations in particulate matter with an aerodynamic diameter of 2.5 µm or less (PM2.5) exposure on assisted reproductive technology (ART) outcomes.

METHODS

This retrospective study, conducted at the First People's Hospital of Shangqiu, analyzed data from 13,476 patients who underwent ART procedures between February 2018 and December 2022. Patients were categorized based on seasonal PM2.5 exposure levels. A generalized additive model (GAM), linear regression analysis, and multivariate logistic regression were used to assess the relationship between PM2.5 exposure and ART outcomes, including oocyte and embryo quality, pregnancy rates, live birth rates, and miscarriage rates.

RESULTS

Significant differences were observed in oocyte number, metaphase II (MII) oocyte number, transferable embryos, and good-quality embryos across seasonal PM2.5 exposure subgroups. Pregnancy rates and live birth rates also demonstrated statistically significant variations. Linear regression analysis revealed a consistent negative correlation between PM2.5 concentrations and key ART outcomes. Multivariate logistic regression analysis, adjusting for age and seasonal variations, confirmed a significant negative association between PM2.5 exposure and both pregnancy rates (OR = 0.995, 95% CI: 0.994-0.996, p < 0.001) and live birth rates (OR = 0.996, 95% CI: 0.995-0.997, p < 0.001). However, no significant relationship was found between PM2.5 exposure and miscarriage rates. GAM analysis further identified a nonlinear, threshold-like association between pregnancy outcomes and predictive factors, with significantly higher live birth rates observed in spring, summer, and autumn compared to winter.

CONCLUSIONS

The study complements existing evidence that exposure to PM2.5 can lead to decreased success rates of pregnancy and live births, as well as significantly impact the outcomes of ART. Future research should focus on developing strategies to mitigate the adverse effects of environmental pollution on ART success rates.

The effect of chronic inflammation on female fertility

In brief

Chronic inflammation causes serious medical conditions in many organs and tissues, including female fertility. Here we review the current literature, showing that chronic inflammation has a negative impact on oocyte quality, folliculogenesis, hormone production, immune signaling and other processes that affect fertility in females.

Abstract

Inflammation has key biological roles in the battle against pathogens and additional key processes in development and tissue homeostasis. However, when inflammation becomes chronic, it can become a serious medical concern. Chronic inflammation has been shown to contribute to the etiology and symptoms of serious medical conditions such as ulcerative colitis, cardiovascular diseases, endometriosis and various cancers. One of the less recognized symptoms associated with chronic inflammation is its effect on reproduction, specifically on female fertility. Here we review the current literature, showing that chronic inflammation has a negative impact on oocyte quality, folliculogenesis, hormone production, immune signaling and other processes that affect fertility in females. We discuss several factors involved in the etiology of chronic inflammation and its effect on female fertility. We also discuss possible mechanisms by which these effects may be mediated and how interventions may mitigate the effect of chronic inflammation. Finally, we discuss the notion that in many cases, the effect of chronic inflammation is tightly correlated with and resembles the effect of aging, drawing interesting parallels between these processes, possibly through the effect of aging-associated inflammaging.

Association between PM2.5 components and poor ovarian response in assisted reproductive technology patients: A retrospective cohort study identifying sensitive exposure windows in China

Environmental factors, particularly various components of fine particulate matter (PM2.5) (i.e., sulfate [SO42-], nitrate [NO3-], ammonium [NH4+], organic matter [OM] and black carbon [BC]), are increasingly recognized as potential risk factors for poor ovarian response (POR) in fertility treatments. However, existing research is limited, and the critical periods of vulnerability to exposure to PM2.5 and its components remain unclear. In this retrospective cohort study, we included 38,619 patients undergoing their first in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) treatment, defining POR as the primary outcome based on the POSEIDON criteria. We divided the six months prior to oocyte pick up (OPU) into different exposure windows and used logistic regression models to assess the association between pollutants and POR. Results showed that exposure to PM2.5 and its components in the three months before OPU significantly increased the odds of POR. The distributed lag nonlinear model (DLNM) analysis revealed the lagged effects of PM2.5 component exposure, particularly during lag weeks 2-5, where exposure was significantly associated with the occurrence of POR. This period may represent a sensitive window for exposure. Meanwhile, the restricted cubic spline (RCS) analysis indicated that the odds of POR gradually increased with higher pollutant concentrations. These findings underscore the urgent need for public health measures during sensitive stages of follicular development, particularly policies aimed at reducing environmental pollutant exposure among women of reproductive age to protect reproductive health.

Particulate air pollution at the time of oocyte retrieval is independently associated with reduced odds of live birth in subsequent frozen embryo transfers

STUDY QUESTION

Does exposure to particulate matter (PM) air pollution prior to oocyte retrieval or subsequent frozen embryo transfer (FET) affect the odds of live birth?

SUMMARY ANSWER

Live birth rates are lower when particulate matter (PM2.5 and PM10) levels are higher prior to oocyte retrieval, regardless of the conditions at the time of embryo transfer.

WHAT IS KNOWN ALREADY

Exposure to air pollution is associated with adverse reproductive outcomes, including reduced fecundity and ovarian reserve, and an increased risk of infertility and pregnancy loss. It is uncertain whether the effect on ART outcomes is due to the effects of pollution on oogenesis or on early pregnancy.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort study included 3659 FETs in 1835 patients between January 2013 and December 2021, accounting for all FETs performed at a single clinic over the study period. The primary outcome was the live birth rate per FET. Outcome data were missing for two embryo transfers which were excluded. Daily levels of PM2.5, PM10, nitric oxide, nitrogen dioxide, sulphur dioxide, ozone and carbon monoxide were collected during the study period and calculated for the day of oocyte retrieval and the day of embryo transfer, and during the preceding 2-week, 4-week, and 3-month periods.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Clinical and embryological outcomes were analysed for their association with pollution over 24 hours, 2 weeks, 4 weeks, and 3 months, with adjustment for repeated cycles per participant, age at the time of oocyte retrieval, a quadratic age term, meteorological season, year, and co-exposure to air pollutants. Multi-pollutant models were constructed to adjust for co-exposures to other pollutants. Median concentrations in pollutant quartiles were modelled as continuous variables to test for overall linear trends; a Bonferroni correction was applied to maintain an overall alpha of 0.05 across the four exposure periods tested.

MAIN RESULTS AND THE ROLE OF CHANCE

Increased PM2.5 exposure in the 3 months prior to oocyte retrieval was associated with decreased odds of live birth (linear trend P = 0.011); the odds of live birth when PM2.5 concentrations were in the highest quartile were reduced by 34% (OR 0.66, 95% CI 0.47-0.92) when compared to the lowest quartile. A consistent direction of effect was seen across other exposure periods prior to oocyte retrieval, with an apparent dose-dependent relationship. Increased exposure to PM10 particulate matter in the 2 weeks prior to oocyte retrieval was associated with decreased odds of live birth (linear trend P = 0.009); the odds of live birth were decreased by 38% (OR 0.62, 95% CI 0.43-0.89, P = 0.010) when PM10 concentrations were in the highest quartile compared with the lowest quartile. Consistent trends were not seen across other exposure periods. None of the gaseous pollutants had consistent effects, prior to either oocyte retrieval or embryo transfer.

LIMITATIONS, REASONS FOR CAUTION

This was a retrospective cohort study, however, all FETs during the study period were included and data were missing for only two FETs. The results are based on city-level pollution exposures, and we were not able to adjust for all possible factors that may affect live birth rates. Results were not stratified based on specific patient populations, and it was not possible to calculate the cumulative live birth rate per commenced cycle.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study to specifically analyse FETs to separate the effects of environmental exposures prior to oocyte retrieval from those around the time of embryo transfer. Our findings suggest that increased PM exposure prior to oocyte retrieval is associated with reduced live birth rate following FET, independent of the conditions at the time of embryo transfer. Importantly, the air quality during the study period was excellent, suggesting that even 'acceptable' levels of air pollution have detrimental reproductive effects during gametogenesis. At the low pollution levels in our study, exposure to gaseous pollutants did not appear to affect live birth rates. This has important implications for our understanding of the effects of pollution on reproduction, and highlights the urgent need for effective policies limiting pollution exposure to protect human health and reproduction.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was provided for this study. S.J.L. is supported by the Jean Murray Jones Scholarship from the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, has received educational sponsorship from Besins, Ferring, Merck, and Organon, honoraria from Hologic and Organon, consulting fees from Merck unrelated to the current study, and is a member of the Reproductive Technology Council of Western Australia. S.J.L. and R.J.H. are board members of Menopause Alliance Australia. C.S.R., M.W., and E.N. have no conflicts of interest to declare. R.J.H. is the Medical Director of Fertility Specialists of Western Australia, the National Medical Director of City Fertility Australia, and a shareholder in CHA SMG. He chairs the Western Australian Minister's Expert Panel on ART and Surrogacy. R.J.H. has made presentations for and received honoraria from Merck, Merck-Serono, Origio, Igenomix, Gideon-Richter, and Ferring, and has received support for attending meetings from Merck, Organon, and Ferring.

TRIAL REGISTRATION NUMBER

N/A.

Associations of ambient air pollutants with pregnancy outcomes in women undergoing assisted reproductive technology and the mediating role of ovarian reserve: A longitudinal study in eastern China

Existing evidence has explored the relationship between exposure to air pollutants with ovarian reserve in women receiving assisted reproductive technology (ART). However, few studies have followed up on ART pregnancy outcomes and evaluated how ovarian reserve is involved in the association between air pollutant exposure and specific ART outcomes. We aimed to determine whether air pollutants affect ART outcomes by interfering with ovarian reserve through long-term follow-up. A total of 5354 women who underwent ART treatment and completed antral follicle count (AFC) detection at the First Affiliated Hospital of University of Science and Technology of China between 2018 and 2020 were involved. Exposure concentrations (0.1° × 0.1°) for three aerodynamic diameters of particulate matter (PM1, PM2.5, PM10) and three oxidized pollutants (NO2, SO2, O3) were assigned to each individual according to the latitude and longitude of the participant's residential address. Multivariate linear mixed effects models (LMMs) were performed to estimate the impacts of exposure to air pollutants during the first 6 months of AFC and longer periods on ovarian reserve capacity and ART pregnancy outcomes. Exposure to PM1 (OR: 0.914, 95%CI: 0.845-0.988), PM2.5 (OR: 0.908, 95%CI: 0.850-0.970), PM10 (OR: 0.924, 95%CI: 0.865-0.987), and SO2 (OR: 0.908, 95%CI: 0.843-0.978) was linked with decreased OR for live birth. In addition, with each IQR increase in PM1, PM2.5, PM10, SO2, and NO2, AFC levels decreased by 0.370, 0.395, 0.064, 0.311, and 0.465, respectively. The mediation effect was more pronounced for NO2 and SO2, with AFCs explaining 26.83 % and 9.54 % of their associations with live birth, respectively. Additionally, 6.49 %, 9.16 %, and 6.79 % of live birth failures were ascribed to PM1, PM2.5, and PM10, respectively. Findings of this study suggest that exposure to air pollutants may affect reproductive outcomes in women receiving ART by reducing their ovarian reserve capacity.

Fine particulate matter and ovarian health: A review of emerging risks

Fine particulate matter (PM2.5) pollution has raised significant public concerns, especially for vulnerable populations. Studies have indicated the association between PM2.5 and ovarian disorders, although the mechanisms underlying the effects have not yet been fully elucidated. In this review, we elucidated three main conditions pertaining to ovarian function that may result from exposure to PM2.5: diminished ovarian reserve, polycystic ovary syndrome, and infertility. Specific effects of ovarian disorders caused by PM2.5 are discussed, including reactive oxygen species, apoptosis, DNA damage, and inflammation.

Barriers and facilitators experienced by South Korean women undergoing fertility treatment: A qualitative socioecological study

The purpose of this qualitative study was to use interview data to identify and describe the intrapersonal, interpersonal, community, and policy barriers and facilitators experienced by South Korean women undergoing fertility treatment. The researchers conducted one-on-one interviews with 14 women who had undergone fertility treatment and then completed a thematic content analysis on the collected interview data. Guided by the socioecological model, the researchers explored the barriers and facilitators women experienced during fertility treatment. The participants described their struggles and -emotional distress as well as their coping mechanisms: addressing their physical and emotional stress; soliciting support from their husband, personal network, online peers, and healthcare team; and seeking government financial assistance. The information gained from this study can help healthcare providers and government agencies design effective psychosocial and national policies and interventions for this population.

Air pollutants and ovarian reserve: a systematic review of the evidence

Background

Growing evidence indicates an association between ambient air pollution and decreased human reproductive potential. This study aims to systematically review the association between air pollutants and female ovarian reserve.

Methods

The literature was searched in six electronic databases through June 2024. Screening the 136 articles retrieved for inclusion criteria resulted in the selection of 15 human observational studies that evaluated the effect of environmental pollutants on ovarian reserve markers. The study protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO, registration code: CRD42023474218).

Results

The study design of the selected studies was found to be cross-sectional (2 of 15), retrospective cohort (10 of 15), prospective cohort (2 of 15), and case-control (1 of 15). The study population was distributed as follows: Asians (53%, eight studies), Americans (33%, five studies), and Europeans (14%, two studies). The main findings showed a higher body of evidence for the environmental pollutants PM2.5, PM10, and NO2, while a low body of evidence for PM1, O3, SO2, and a very low body of evidence for benzene, formaldehyde, and benzo(a)pyrene, yet consistently showing significant inverse association data. The overall methodological quality of the selected studies was rated moderated across the 14 domains of the National Institutes of Health (NIH) toolkit.

Conclusion

The data suggest that increased exposure to air pollutants seems to be associated with reduced ovarian reserve, with the most substantial evidence for pollutants such as PM2.5, PM10, and NO2. However, more evidence is needed to draw conclusions about causality.

Mixed effects of ambient air pollutants on oocyte-related outcomes: A novel insight from women undergoing assisted reproductive technology

Air pollution is widely acknowledged as a significant risk factor for human health, especially reproductive health. Nevertheless, many studies have disregarded the potentially mixed effects of air pollutants on reproductive outcomes. We performed a retrospective cohort study involving 8048 women with 9445 cycles undergoing In Vitro Fertilization (IVF) and Intracytoplasmic Sperm Injection (ICSI) in China, from 2017 to 2021. A land-use random forest model was applied to estimate daily residential exposure to air pollutants, including sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and fine particulate matter (PM2.5). Individual and joint associations between air pollutants and oocyte-related outcomes of ART were evaluated. In 90 days prior to oocyte pick-up to oocyte pick-up (period A), NO2, O3 and CO was negatively associated with total oocyte yield. In the 90 days prior to oocyte pick-up to start of gonadotropin medication (Gn start, period B), there was a negative dose-dependent association of exposure to five air pollutants with total oocyte yield and mature oocyte yield. In Qgcomp analysis, increasing the multiple air pollutants mixtures by one quartile was related to reducing the number of oocyte pick-ups by -2.00 % (95 %CI: -2.78 %, -1.22 %) in period A, -2.62 % (95 %CI: -3.40 %, -1.84 %) in period B, and -0.98 % (95 %CI: -1.75 %, -0.21 %) in period C. During period B, a 1-unit increase in the WQS index of multiple air pollutants exposure was associated with fewer number of total oocyte (-1.27 %, 95 %CI: -2.16 %, -0.36 %) and mature oocyte (-1.42 %, 95 %CI: -2.41 %, -0.43 %). O3 and NO2 were major contributors with adverse effects on the mixed associations. Additionally, period B appears to be the susceptible window. Our study implies that exposure to air pollution adversely affects oocyte-related outcomes, which raises concerns about the potential adverse impact of air pollution on women's reproductive health.

Reduced human fecundity attributable to ambient fine particles in low- and middle-income countries

BACKGROUND

Exposure to ambient fine particulate matter (PM2.5) has been associated with reduced human fecundity. However, the attributable burden has not been estimated for low- and middle-income countries (LMICs), where the exposure-response function between PM2.5 and the infertility rate has been insufficiently studied.

OBJECTIVE

This study examined the associations between long-term exposure to PM2.5 and human fecundity indicators, namely the expected time to pregnancy (TTP) and 12-month infertility rate (IR), and then estimated PM2.5-attributable burden of infertility in LMICs.

METHODS

We analyzed 164,593 eligible women from 100 Demographic and Health Surveys conducted in 49 LMICs between 1999 and 2021. We assessed PM2.5 exposures during the 12 months before a pregnancy attempt using the global satellite-derived PM2.5 estimates produced by Atmospheric Composition Analysis Group (ACAG). First, we created a series of pseudo-populations with balanced covariates, given different levels of PM2.5 exposure, using a matching approach based on the generalized propensity score. For each pseudo-population, we used 2-stage generalized Gamma models to derive TTP or IR from the probability distribution of the questionnaire-based duration time for the pregnancy attempt before the interview. Second, we used spline regressions to generate nonlinear PM2.5 exposure-response functions for each of the two fecundity indicators. Finally, we applied the exposure-response functions to estimate number of infertile couples attributable to PM2.5 exposure in 118 LMICs.

RESULTS

Based on the Gamma models, each 10 µg/m3 increment in PM2.5 exposure was associated with a TTP increase by 1.7 % (95 % confidence interval [CI]: -2.3 %-6.0 %) and an IR increase by 2.3 % (95 %CI: 0.6 %-3.9 %). The nonlinear exposure-response function suggested a robust effect of an increased IR for high-concentration PM2.5 exposure (>75 µg/m3). Based on the PM2.5-IR function, across the 118 LMICs, the number of infertile couples attributable to PM2.5 exposure exceeding 35 µg/m3 (the first-stage interim target recommended by the World Health Organization global air quality guidelines) was 0.66 million (95 %CI: 0.061-1.43), accounting for 2.25 % (95 %CI: 0.20 %-4.84 %) of all couples affected by infertility. Among the 0.66 million, 66.5 % were within the top 10 % high-exposure infertile couples, mainly from South Asia, East Asia, and West Africa.

CONCLUSION

PM2.5 contributes significantly to human infertility in places with high levels of air pollution. PM2.5-pollution control is imperative to protect human fecundity in LMICs.

Alkali and alkaline earth elements in follicular fluid and the likelihood of diminished ovarian reserve in reproductive-aged women: a case‒control study

BACKGROUND

Imbalances in alkali elements (AEs) and alkaline earth elements (AEEs) cause reproductive disorders. However, it remains unclear whether AEs/AEEs in follicular fluid have a relationship with the serious reproductive disorder known as diminished ovarian reserve (DOR).

METHODS

A nested case‒control study was carried out in China. Follicular fluid samples from 154 DOR patients and 154 controls were collected and assessed for nine AEs/AEE levels. Both the mixed and single effects of the elements on DOR were estimated with a Bayesian kernel machine (BKMR) and logistic regressions.

RESULTS

The DOR group had higher median concentrations of Li, Na, and K in follicular fluid (all P values < 0.05). The logistic regression showed that compared with their lowest tertile, the high tertiles of K [OR:2.45 (1.67-4.43)], Li [OR: 1.89 (1.06-3.42)], and Cs [OR: 1.97 (1.10-3.54)] were significantly associated with the odds of DOR. The BKMR model reported that the DOR likelihood increased linearly across the 25th through 75th percentiles of the nine-AE/AEE mixture, while the AE group contributed more to the overall effect.

CONCLUSION

This study revealed an association in which the likelihood of DOR increased with higher overall concentrations of AE/AEEs in follicular fluid. Among the nine detected elements, K, Li, and Cs exhibited significant individual associations with DOR. We provide new clues for the environmental factors on female fertility decline.

TRIAL REGISTRATION

Retrospectively registered.

Association between neighborhood poverty and ovarian reserve: the ovarian aging study

OBJECTIVE

This study aimed to examine the association between neighborhood poverty and ovarian reserve.

METHODS

Among 1,019 healthy premenopausal women in the Ovarian Aging Study, aggregate exposure to neighborhood poverty was examined in relation to biomarkers of ovarian reserve, antimüllerian hormone (AMH) and antral follicle count (AFC). Specifically, the interaction of age-x-neighborhood poverty was assessed cross-sectionally to determine whether AMH and AFC declines across women may be greater in women exposed to more neighborhood poverty. Neighborhood poverty was assessed by geocoding and linking women's residential addresses in adulthood to US Census data.

RESULTS

Independent of covariates, a significant interaction term showed the association between age and AMH varied by degree of exposure to neighborhood poverty in adulthood ( b = -0.001, P < 0.05). AMH declines increased progressively across women exposed to low, medium, and high levels of neighborhood poverty. In addition, main effects showed that higher neighborhood poverty was related to higher AMH in the younger women only ( b = 0.022, P < 0.01). Results related to AFC were all nonsignificant ( P > 0.05).

CONCLUSIONS

Across women, greater aggregate exposure to neighborhood poverty in adulthood was related to lower ovarian reserve, indexed by AMH. In addition, there was a positive association between neighborhood poverty and AMH in younger women that attenuated in the older women. Together, results suggest that neighborhood disadvantage may have detrimental impacts that manifest as initially higher AMH, resulting in greater ovarian follicle loss over time. However, it remains unclear whether these results examining differences across women may replicate when AMH declines by neighborhood poverty are examined longitudinally.

Association of PM2.5 mass and its components with ovarian reserve in a northern peninsular province, China: The critical exposure period and components

BACKGROUND

A possible role of PM2.5 components on ovarian reserve has not been adequately unexplored.

OBJECTIVE

To evaluate the association between PM2.5 components and women' ovarian reserve over critical exposure periods in northern China, where the level of air pollution is among the nation's highest.

METHODS

We included 15,102 women with serum anti-Müllerian hormone (AMH) measurements from the Center for Reproductive Medicine of Shandong University during 2015-2019. Concentrations of PM2.5 and its five major components (0.1° × 0.1°), including sulfate, nitrate, ammonium, organic matter, and black carbon, were assigned to each residential address. Multivariable linear mixed effect models combined with constituent-residual models were performed to estimate the effect sizes of essential components over six short- to long-term exposure periods.

RESULTS

The strength of association was stronger during the process from primary to small antral follicle compared with other longer windows. For every interquartile range increase in PM2.5 mass was associated with - 8.7% (95%CI: -12.3%, -4.9%) change in AMH and the effect size was greatest for sulfate. Women with the lower level of attained education and those living inland were more susceptible compared with other population subgroups.

CONCLUSION

Exposure to specific components of air pollution during critical exposure windows is associated with a decline in ovarian reserve. These data add to the growing body of evidence that environmental factors have adverse effects on reproductive health, particularly for vulnerable population subgroups.

Ambient ozone and ovarian reserve in Chinese women of reproductive age: Identifying susceptible exposure windows

Little is known about the association of ambient ozone with ovarian reserve. Based on a retrospective cohort study of 6008 women who attended a fertility center in Hubei, China, during 2018-2021, we estimated ozone exposure levels by calculating averages during the development of follicles (2-month [W1], 4-month [W2], 6-month [W3]) and 1-year before measurement (W4) according to Tracking Air Pollution in China database. We used multivariate logistic regression and linear regression models to investigate association of ozone exposure with anti-müllerian hormone (AMH), the preferred indicator of ovarian reserve. Each 10 μg/m3 increases in ozone were associated with 2.34% (0.68%, 3.97%), 2.08% (0.10%, 4.01%), 4.20% (1.67%, 6.67%), and 8.91% (5.79%, 11.93%) decreased AMH levels during W1-W4; AMH levels decreased by 15.85%, 11.90%, 16.92% in the fourth quartile during W1, W3, and W4 when comparing the extreme quartile, with significant exposure-response relationships during W4 (P < 0.05). Ozone exposure during W1 was positively associated with low AMH. Additionally, we detected significant effect modification by age, body mass index, and temperature in ozone-associated decreased AMH levels. Our findings highlight the potential adverse impact of ozone pollution on female ovarian reserve, especially during the secondary to small antral follicle stage and 1-year before measurement.

Exposure to air pollution and ovarian reserve parameters

Exposure to air pollution is associated with many different health effects, especially cardiovascular and respiratory diseases. Additionally, highly significant links between exposure to air pollution and fertility, particularly male fertility was observed, however the studies regarding exposure to selected air pollutants and female fertility assessed by ovarian reserve are rare. Hence, the main aim of the study was to analyze relationship between exposure to ambient air pollution and ovarian reserve parameters among Polish women. The study population consisted of 511 women, who attended to infertility clinic because of diagnostic purposes. Participants filled in the questionnaire about social-demographic, lifestyle and health factors. Infertility specialists assessed ovarian parameters such as: antral follicle count (AFC) and concentration of hormones: Anti-Müllerian hormone (AMH), follicle stimulating hormone (FSH) and estradiol (E2). The air pollutants level (sulfur dioxide, nitrogen dioxide, carbon monoxide, ozone, particulate matters) were obtained via National Environmental Protection Inspectorate database. Significant negative association between PM2,5 and AHM (p = 0.032) as well as AFC (p = 0.044) was observed. Moreover, SO2 concentrations decrease AFC (p = 0.038). The results also suggest that PM10, PM2.5, SO2 exposure on antral follicle count may be more pronounced among women with a female factor infertility diagnosis. Additionally, exposure to PM2.5 and NOx on AFC and AMH was stronger among older women (> 35 years of age). To conclude, the present study found that air pollution could lead to decrease in follicle antral count and Anti-Müllerian hormone level, especially exposure to PM2,5 and SO2 thus the evidence suggest negative impact to ovarian reserve.

Association of exposure to ozone and fine particulate matter with ovarian reserve among women with infertility

Evidence linking diminished ovarian reserve, a significant cause of female infertility, and exposure to particulate matter with aerodynamic diameters ≤2.5 μm (PM2.5) or O3 exposure remains a critical knowledge gap in female fertility. This study investigated the association between ambient PM2.5, O3 pollution, and anti-Müllerian hormone (AMH), a sensitive marker of ovarian reserve, in reproductive-aged Chinese women. We enrolled 2212 women with spontaneous menstrual cycles who underwent AMH measurements at a reproductive medicine center between 2018 and 2021. The daily mean concentrations of outdoor PM2.5 and O3 were estimated using a validated spatiotemporal model, followed by matching the participants' residential addresses. Three exposure periods were designed according to AMH expression patterns during follicle development. A generalized linear model was used to investigate changes in AMH associated with air pollution. The results showed a mean AMH level of 3.47 ± 2.61 ng/mL. During the six months from primary to early antral follicle stage (Period 1), each 10 μg/m3 increase in PM2.5 and O3 exposure was associated with AMH changes of -0.21 (95% confidence interval [CI]: -0.48, 0.06) ng/mL and -0.31 (95% CI: -0.50, -0.12) ng/mL, respectively. Further analyses indicated that the reduced ovarian reserve measured by AMH level was only significantly associated with PM2.5 exposure during follicle development from the primary to preantral follicle stage (Period 2) but was significantly associated with O3 exposure during Periods 1, 2, and 3. These observations were robust in the dual-pollutant model considering co-exposure to PM2.5 and O3. The results indicated an inverse association between ovarian reserve and ambient O3 exposure and suggested distinct susceptibility windows for O3 and PM2.5 for reduced ovarian reserve. These findings highlight the need to control ambient air pollution to reduce invisible risks to women's fertility, especially at high O3 concentrations.

Ambient traffic related air pollution in relation to ovarian reserve and oocyte quality in young, healthy oocyte donors

Studies in mice and older, subfertile women have found that air pollution exposure may compromise female reproduction. Our objective was to evaluate the effects of air pollution on ovarian reserve and outcomes of ovarian stimulation among young, healthy females. We included 472 oocyte donors who underwent 781 ovarian stimulation cycles at a fertility clinic in Atlanta, Georgia, USA (2008-2019). Antral follicle count (AFC) was assessed with transvaginal ultrasonography and total and mature oocyte count was assessed following oocyte retrieval. Ovarian sensitivity index (OSI) was calculated as the total number of oocytes divided by total gonadotrophin dose × 1000. Daily ambient exposure to nitric oxide (NOx), carbon monoxide (CO), and particulate matter ≤ 2.5 (PM2.5) was estimated using a fused regional + line-source model for near-surface releases at a 250 m resolution based on residential address. Generalized estimating equations were used to evaluate the associations of an interquartile range (IQR) increase in pollutant exposure with outcomes adjusted for donor characteristics, census-level poverty, and meteorological factors. The median (IQR) age among oocyte donors was 25.0 (5.0) years, and 31% of the donors were racial/ethnic minorities. The median (IQR) exposure to NOx, CO, and PM2.5 in the 3 months prior to stimulation was 37.7 (32.0) ppb, 612 (317) ppb, and 9.8 (2.9) µg/m3, respectively. Ambient air pollution exposure in the 3 months before AFC was not associated with AFC. An IQR increase in PM2.5 in the 3 months before AFC and during stimulation was associated with -7.5% (95% CI -14.1, -0.4) and -6.4% (95% CI -11.0, -1.6) fewer mature oocytes, and a -1.9 (95% CI -3.2, -0.5) and -1.0 (95% CI -1.8, -0.2) lower OSI, respectively. Our results suggest that lowering the current 24-h PM2.5 standard in the US to 25 µg/m3 may still not adequately protect against the reprotoxic effects of short-term PM2.5 exposure.

Fine particulate matter and its constituent on ovarian reserve: Identifying susceptible windows of exposure

BACKGROUND

Little is known about the associations of exposure to fine particulate matter (PM2.5) and its constituents with ovarian reserve, and the potential susceptible window of exposure remains unclear.

METHODS

We performed a retrospective cohort study of 5189 women who attended a fertility center in Hubei, China, during 2019-2022, and estimated concentrations of PM2.5 and its major constituents during the development of follicles (4th-6th month [W1], 0-4th month [W2], 0-6th month [W3]) and 1-year before measurement (W4) based on Tracking Air Pollution in China database. We used multivariable linear regression and logistic regression models to examine the associations of PM2.5 and its constituent exposures with anti-Müllerian hormone (AMH), the preferred indicator of ovarian reserve.

RESULTS

We observed significantly decreased AMH levels associated with increasing PM2.5 concentrations, with the percent changes (95 % confidence intervals [CIs]) of 1.99 % (0.24 %-3.71 %) during W1 and 3.99 % (0.74 %-7.15 %) during W4 for per 10 μg/m3 increases in PM2.5.When PM2.5 exposure levels were equal to 50th percentile (32.6-42.3 μg/m3) or more, monotonically decreased AMH levels and increased risks of low AMH were seen with increasing PM2.5 concentrations during W1 and W4 (P < 0.05). Black carbon (BC), ammonium (NH4+), nitrate (NO3-), and organic matter (OM) during W1, and NH4+, NO3-, as well as sulfate (SO42-) during W4 were significantly associated with decreased AMH. Moreover, PM2.5 and SO42- exposures during W4 were positively associated with low AMH. Additionally, the associations were stronger among women aged <35 years, lived in urban regions, or measured AMH in cold-season (P for interaction <0.05).

CONCLUSION

PM2.5 and specific chemical components (particularly NH4+, NO3-, and SO42-) exposure during the secondary to antral follicle stage and 1-year before measurement were associated with diminished ovarian reserve (DOR), indicating the adverse impact of PM2.5 and its constituent exposures on female reproductive potential.

Potential factors result in diminished ovarian reserve: a comprehensive review

The ovarian reserve is defined as the quantity of oocytes stored in the ovary or the number of oocytes that can be recruited. Ovarian reserve can be affected by many factors, including hormones, metabolites, initial ovarian reserve, environmental problems, diseases, and medications, among others. With the trend of postponing of pregnancy in modern society, diminished ovarian reserve (DOR) has become one of the most common challenges in current clinical reproductive medicine. Attributed to its unclear mechanism and complex clinical features, it is difficult for physicians to administer targeted treatment. This review focuses on the factors associated with ovarian reserve and discusses the potential influences and pathogenic factors that may explain the possible mechanisms of DOR, which can be improved or built upon by subsequent researchers to verify, replicate, and establish further study findings, as well as for scientists to find new treatments.

Acupuncture and moxibustion for diminished ovarian reserve: A scoping review

OBJECTIVE

Diminished ovarian reserve (DOR) refers to the decreased number and quality of oocytes in the ovary. Acupuncture and moxibustion has a certain effect on DOR; however, the number of studies and reports of research evidence are limited. This study aimed to conduct a scoping review of the clinical research status of acupuncture and moxibustion for treating patients with DOR.

METHOD

PubMed, Cochrane Library, Excerpta Medica database, Allied and Complementary Medicine Database, Chinese Biological Medicine, China National Knowledge Infrastructure, VIP Database for Chinese Technical Periodicals, and Wanfang database were searched from January 2010 to May 2022 using keywords and medical subject heading terms. After applying the inclusion and exclusion criteria, relevant studies were selected. Structured tables and descriptive charts were made to visually express research features by using Excel, Original, IBM SPSS Model 18.0, Adobe Illustrator and other software packages. Report quality was evaluated for Cochrane bias using Review Manager 5.3.

RESULTS

Overall, 851 studies were identified; of these, 90 met the inclusion criteria. The results extracted from these studies were classified into four categories: research characteristics, study type, acupuncture and moxibustion prescriptions, and efficacy observation.

CONCLUSIONS

The quality assessment of acupuncture and moxibustion for DOR is not ideal. Therefore, standardisation and normalisation should be strengthened, and high-quality evidence is needed to further demonstrate the effectiveness of this approach. Due to heterogeneity in DOR diagnosis, the observation index should be updated with reference to the latest research to improve efficacy evaluation.

Ambient black carbon particles in human ovarian tissue and follicular fluid

Evidence indicates a link between exposure to ambient air pollution and decreased female fertility. The ability of air pollution particles to reach human ovarian tissue and follicles containing the oocytes in various maturation stages has not been studied before. Particulate translocation might be an essential step in explaining reproductive toxicity and assessing associated risks. Here, we analysed the presence of ambient black carbon particles in (i) follicular fluid samples collected during ovum pick-up from 20 women who underwent assisted reproductive technology treatment and (ii) adult human ovarian tissue from 5 individuals. Follicular fluid and ovarian tissue samples were screened for the presence of black carbon particles from ambient air pollution using white light generation by carbonaceous particles under femtosecond pulsed laser illumination. We detected black carbon particles in all follicular fluid (n = 20) and ovarian tissue (n = 5) samples. Black carbon particles from ambient air pollution can reach the ovaries and follicular fluid, directly exposing the ovarian reserve and maturing oocytes. Considering the known link between air pollution and decreased fertility, the impact of such exposure on oocyte quality, ovarian ageing and fertility needs to be clarified urgently.

Long-term exposure to air pollution and anti-mullerian hormone rate of decline: a population-based cohort study in Tehran, Iran

Anti-mullerian hormone (AMH) concentration is a marker of ovarian reserve that decreases with age. However, a decrease in AMH may occur more rapidly under the influence of environmental factors. The present study investigated the association between long-term exposure to ambient air pollutants with serum concentrations of AMH and the AMH rate of decline. This study included 806 women with median age of 43 years (interquartile range: 38-48) participating in the Tehran Lipid and Glucose Study (TLGS) that were followed from 2005 to 2017. The AMH concentration and the demographic, anthropometric, and personal health parameters of the study participants were obtained from the TLGS cohort database. Air pollutant data were collected from the monitoring stations and the individual exposures were estimated by previously developed land use regression (LUR) models. Multiple linear regression analysis was used to estimate linear relationships between the air pollutant exposures and serum concentration of AMH and with the AMH declination rate. The results show no statistically significant associations between exposures to any of the air pollutants (including PM10, PM2.5, SO2, NO, NO2, NOX, and benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene (BTEX), and total BTEX) with serum concentration of AMH. Compared to the first tertile, no statistically significant associations were observed between the second or third tertiles of air pollutants, with the AMH rate of decline. In this study, we did not find significant association between air pollution and AMH in middle age women in Tehran, Iran. Future work may study such associations in younger women.

Mixed and single effects of endocrine disrupting chemicals in follicular fluid on likelihood of diminished ovarian reserve: A case-control study

Endocrine-disrupting chemicals (EDCs) are a group of the most widely spread pollutants. Their impacts on reproductive health have become public concerns. Diminished ovarian reserve (DOR) is a disorder of ovarian function. Associations between EDC and DOR have been inconsistent. Very little research investigated the joint effects of multiple EDCs. Here, we performed a case-control study among 64 DOR women and 86 controls. Twenty-one EDC chemicals were assessed in follicular fluid, including parabens, phenols, phthalates and poly-fluoroalkyl substances. Both mixed and single effects of EDCs on DOR were evaluated and validated with a Bayesian kernel machine and logistic regressions. We found that the likelihood of DOR significantly increased with rising levels of the 21-EDC mixture, with an odds ratio (OR) and 95% confidence interval (CI) of 2.12 (1.17-3.83) for the 75th percentile compared to its median level. The overall effect was higher than effects of each subgroup. BP4, MECPP, and PFHxA were driving the association to the mixture, and their single effects were validated, with individual ORs of 8.25 (95%CI:3.45-12.21), 1.92 (95%CI:1.02-4.09), and 1.84 (95%CI:1.08-3.86), respectively. In conclusion, we provided new pollutant markers for DOR and emphasized the importance of the effects of EDC mixtures on female reproductive health.

Exposure of ambient PM2.5 during gametogenesis period affects the birth outcome: Results from the project ELEFANT

Various environmental and behavioural factors influence neonatal health. Gamete formation (gametogenesis) is a crucial period which affects embryo development and neonatal health and ambient air pollution exposure at this stage may lead to an adverse birth outcome. Previous epidemiological and toxicological research demonstrated a strong association between maternal ambient air pollution exposure and adverse birth outcomes. However, the joint exposure-outcome of paternal exposure (76 days before the last menstruation and 14 days after the last menstruation) and maternal exposure (14 days after the last menstruation) when exploring the mechanism of the influence of air pollutants on pregnancy outcome and neonatal health remains unexplored. Here, in the Project Environmental and LifEstyle FActors iN metabolic health throughout life-course Trajectories (ELEFANT), we collected the data of 10,960 singleton pregnant women with 24-42 completed gestational weeks and included them in this study. A multinominal logistic regression model was applied to investigate the association between adverse birth outcomes and ambient PM_2.5 exposure levels during spermatogenesis and oogenesis. Results from the binary classification of ambient PM_2.5 exposure showed that the risk of abnormal birthweight was significantly greater when ambient PM_2.5 exposure was both higher during spermatogenesis and oogenesis, with RRs of 1.86 (95% CI: 1.02, 3.39). The risk of macrosomia (RR: 1.88 (95% CI: 1.13, 3.12)) increased significantly when ambient PM_2.5 levels were higher during spermatogenesis. Primiparity and primigravity are more likely to be influenced by higher ambient PM_2.5 levels during spermatogenesis. In conclusion, more attention should be paid to higher exposure level of ambient PM_2.5 during spermatogenesis.

Air pollution exposure and ovarian reserve impairment in Shandong province, China: The effects of particulate matter size and exposure window

BACKGROUND

Lack of evidence exists on whether air pollution exposure may affect ovarian reserve, especially for Chinese women.

OBJECTIVES

To explore the association between exposure to various air pollutants and anti-Müllerian hormone (AMH), a predictor of ovarian reserve, over different exposure windows in Shandong Province, China.

METHODS

We enrolled 18,878 women who had AMH measurements in the Center for Reproductive Medicine, Shandong University during 2010-2019. Daily average concentrations of ambient particulate matter with diameters ≤1 μm/2.5 μm/10 μm (PM₁, PM_2.5, and PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) were developed at a spatial resolution of 0.01° × 0.01°, and assigned to the residential addresses. Three exposure windows were considered, i.e., the process from primary to small antral follicle stage (W1), from primary to secondary follicle stage (W2), and from secondary to small antral follicle stage (W3). The air pollution-AMH association was fitted using the multivariable linear mixed effect model with adjustment for potential confounders. Stratified analyses were performed by age group, overweight status, residential region, and educational level.

RESULTS

The level of AMH changed by -8.8% (95% confidence interval (CI): -12.1%, -5.3%), -2.1% (95% CI: -3.5%, -0.6%), -1.9% (95% CI: -3.3%, -0.5%), and -4.5% (95% CI: -7.1%, -1.9%) per 10 μg/m³ increase in PM₁, PM_2.5, PM₁₀, and NO₂, respectively, during W1. The effect estimates were significant during W2 for PM₁, PM_2.5 and NO₂ while minimal association was observed in W3. Greater vulnerability for certain air pollutants were observed for women who lived in inland areas and were less educated.

CONCLUSIONS

We found that ovarian reserve was negatively associated with air pollution exposure for women, particularly from the primary to secondary follicle stage. The effect estimate increased by the reduction in the diameter of PMs, which also varied across population sub-groups.

Environmental Exposures and Anti-Müllerian Hormone: A Mixture Analysis in the Nurses' Health Study II

BACKGROUND

Previous studies have linked environmental exposures with anti-Müllerian hormone (AMH), a marker of ovarian reserve. However, associations with multiple environment factors has to our knowledge not been addressed.

METHODS

We included a total of 2,447 premenopausal women in the Nurses' Health Study II (NHSII) who provided blood samples during 1996-1999. We selected environmental exposures linked previously with reproductive outcomes that had measurement data available in NHSII, including greenness, particulate matter, noise, outdoor light at night, ultraviolet radiation, and six hazardous air pollutants (1,3-butadiene, benzene, diesel particulate matter, formaldehyde, methylene chloride, and tetrachloroethylene). For these, we calculated cumulative averages from enrollment (1989) to blood draw and estimated associations with AMH in adjusted single-exposure models, principal component analysis (PCA), and hierarchical Bayesian kernel machine regression (BKMR).

RESULTS

Single-exposure models showed negative associations of AMH with benzene (percentage reduction in AMH per interquartile range [IQR] increase = 5.5%, 95% confidence interval [CI] = 1.0, 9.8) and formaldehyde (6.1%, 95% CI = 1.6, 10). PCA identified four major exposure patterns but only one with high exposure to air pollutants and light at night was associated with lower AMH. Hierarchical BKMR pointed to benzene, formaldehyde, and greenness and suggested an inverse joint association with AMH (percentage reduction comparing all exposures at the 75th percentile to median = 8.2%, 95% CI = 0.7, 15.1). Observed associations were mainly among women above age 40.

CONCLUSIONS

We found exposure to benzene and formaldehyde to be consistently associated with lower AMH levels. The associations among older women are consistent with the hypothesis that environmental exposures accelerate reproductive aging.

Airway pollution and smoking in reproductive health

Environmental exposure refers to contact with chemical, biological, or physical substances found in air, water, food, or soil that may have a harmful effect on a person's health. Almost all of the global population (99%) breathe air that contains high levels of pollutants. Smoking is one of the most common forms of recreational drug use and is the leading preventable cause of morbidity and mortality worldwide. The small particles from either ambient (outdoor) pollution or cigarette smoke are inhaled to the lungs and quickly absorbed into the bloodstream. These substances can affect virtually every organ in our body and have been associated with various respiratory, cardiovascular, endocrine, and also reproductive morbidities, including decreased fertility, adverse pregnancy outcomes, and offspring long-term morbidity. This review summarizes the latest literature reporting the reproductive consequences of women exposed to ambient (outdoor) air pollution and cigarette smoking.

Using follicular fluid metabolomics to investigate the association between air pollution and oocyte quality

BACKGROUND AND AIM

Our objective was to use metabolomics in a toxicological-relevant target tissue to gain insight into the biological processes that may underlie the negative association between air pollution exposure and oocyte quality.

METHODS

Our study included 125 women undergoing in vitro fertilization at an academic fertility center in Massachusetts, US (2005-2015). A follicular fluid sample was collected during oocyte retrieval and untargeted metabolic profiling was conducted using liquid chromatography with ultra-high-resolution mass spectrometry and two chromatography columns (C18 and HILIC). Daily exposure to nitrogen dioxide (NO2), ozone, fine particulate matter, and black carbon was estimated at the women's residence using spatiotemporal models and averaged over the period of ovarian stimulation (2-weeks). Multivariable linear regression models were used to evaluate the associations between the air pollutants, number of mature oocytes, and metabolic feature intensities. A meet-in-the-middle approach was used to identify overlapping features and metabolic pathways.

RESULTS

Of the air pollutants, NO2 exposure had the largest number of overlapping metabolites (C18: 105; HILIC: 91) and biological pathways (C18: 3; HILIC: 6) with number of mature oocytes. Key pathways of overlap included vitamin D3 metabolism (both columns), bile acid biosynthesis (both columns), C21-steroid hormone metabolism (HILIC), androgen and estrogen metabolism (HILIC), vitamin A metabolism (HILIC), carnitine shuttle (HILIC), and prostaglandin formation (C18). Three overlapping metabolites were confirmed with level-1 or level-2 evidence. For example, hypoxanthine, a metabolite that protects against oxidant-induced cell injury, was positively associated with NO2 exposure and negatively associated with number of mature oocytes. Minimal overlap was observed between the other pollutants and the number of mature oocytes.

CONCLUSIONS

Higher exposure to NO2 during ovarian stimulation was associated with many metabolites and biologic pathways involved in endogenous vitamin metabolism, hormone synthesis, and oxidative stress that may mediate the observed associations with lower oocyte quality.

Poor ovarian response is associated with air pollutants: A multicentre study in China

BACKGROUND

Human evidence on the association between air pollution and ovarian response is scarce. Poor ovarian response (POR) with an incidence of 5-35% is a tricky problem in IVF treatment.

METHODS

In this large-scale multicentre study, we included 2186 women with POR (< 4 oocytes retrieved) and 7033 women with a normal ovarian response (10-15 oocytes retrieved), who underwent their first in vitro fertilization treatment in five cities in northern China during 2015-2020. Average concentrations of six air pollutants (PM2.5, PM10, O3, NO2, CO, and SO2) during different exposure windows (5 days, 1, 3, 6, and 12 months) before oocyte pick up (OPU) were calculated using data from the air monitoring station nearest to the residential site as approximate individual exposure. Logistic regression models were employed to assess the association between exposure to air pollutants and the risk of POR. Stratification analyses were conducted based on female age. Sensitivity analyses were performed in poor responders identified by Bologna criteria and women with unexpected POR.

FINDINGS

We detected that increased SO2 exposure during all exposure windows before OPU was associated with a higher risk of POR, especially for women ≤ 30 years old. In the stratified analysis, the effect sizes were larger for the unexpected poor ovarian response.

INTERPRETATION

The findings provide human evidence for adverse effects of exposure to ambient air pollutants on ovarian response and underscore the need to reduce ambient air pollution exposure in women of reproductive age to protect human fertility.

FUNDING

This study was granted from the National Key Research and Development Program (2018YFC1004203), the Major Special Construction Plan for Discipline Construction Project of China Medical University (3110118033), the Shengjing Freelance Researcher Plan of Shengjing Hospital of China Medical University, and the National Natural Science Foundation of China (82071601), the Central Government Special Fund for Local Science and Technology Development (2020JH6/10500006).

Plasma proteomic signature of cellular senescence and markers of biological aging among postmenopausal women

We aimed to investigate the association of circulatory senescence-associated secretory phenotypes (SASP) produced by senescent cells with chronological and menopausal age in women aged 45 years or more. The proteomic profiles for 32 SASP factors of plasma samples were measured in 76 healthy postmenopausal women aged 46-82 years from the Korean Genome and Epidemiology Study Cardiovascular Disease Association Study (KoGES-CAVAS). We assessed the association between the SASP factors and aging indicators (chronological age, menopausal age, and years since menopause) using single- and multi-protein models. First, we composed a profile of proteins associated with chronological age, menopausal age, and years since menopause. In a single-protein model, three proteins (growth differentiation factor 15 (GDF15), insulin-like growth factor binding protein-2 (IGFBP-2), and tumor necrosis factor-α (TNF-α)) are positively associated with chronological age. Menopausal age and years since menopause are interrelated with Interlukin-8 (IL-8). The direction of association between menopausal age and monocyte chemoattractant protein-1 (MCP-1) was only negative, and IGFBP-2 and TNF-α were significant in all three aging factors. We also constructed parsimonious multi-protein models to confirm the association of the proteomic signature for aging after adjusting for covariates and the combination of proteomic signature of 13 proteins (GDF15, IFN-γ, IGFBP-2, IGFBP-7, IL-15, IL-1β, IL-17A, IL-8, MCP-1, TIMP-2, TNF-α, VEGF-A, and IP-10) appear to be associated with chronological age and menopausal state of individuals. Thus, by observing association between the selected SASPs and age-related markers among healthy postmenopausal women, we examine how menopause in women relates to proteomic indicators of aging and highlight the potential use of SASP factors as a marker to reflect the state of biological aging attributed by ovarian senescence.

Air pollution and fecundability: Results from a Danish preconception cohort study

BACKGROUND

Animal and epidemiologic studies indicate that air pollution may adversely affect fertility. Epidemiologic studies have been restricted largely to couples undergoing fertility treatment or have retrospectively ascertained time-to-pregnancy among pregnant women.

OBJECTIVES

We examined the association between residential ambient air pollution and fecundability, the per-cycle probability of conception, in a large preconception cohort of Danish pregnancy planners.

METHODS

During 2007-2018, we used the Internet to recruit and follow women who were trying to conceive without the use of fertility treatment. Participants completed an online baseline questionnaire eliciting socio-demographic characteristics, lifestyle factors, and medical and reproductive histories and follow-up questionnaires every 8 weeks to ascertain pregnancy status. We determined concentrations of ambient nitrogen oxides (NOx ), nitrogen dioxide (NO2 ), carbon monoxide (CO), ozone (O3 ), particulate matter <2.5 µm (PM2.5 ) and <10 µm (PM10 ), and sulphur dioxide (SO2 ) at each participant's residential address. We calculated average exposure during the year before baseline, during each menstrual cycle over follow-up and during the entire pregnancy attempt time. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for potential confounders and co-pollutants. The analysis was restricted to the 10,183 participants who were trying to conceive for <12 cycles at study entry whose addresses could be geocoded.

RESULTS

During 12 months of follow-up, 73% of participants conceived. Higher concentrations of PM2.5 and PM10 were associated with small reductions in fecundability. For example, the FRs for a one interquartile range (IQR) increase in PM2.5 (IQR = 3.2 µg/m3 ) and PM10 (IQR = 5.3 µg/m3 ) during each menstrual cycle were 0.93 (95% CI: 0.87, 0.99) and 0.91 (95% CI: 0.84, 0.99), respectively. Other air pollutants were not appreciably associated with fecundability.

CONCLUSIONS

In this preconception cohort study of Danish women, residential exposures to PM2.5 and PM10 were associated with reduced fecundability.