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Background: Fertility-awareness-based methods have been linked to shorter time to conception; however, little is known about the predictors of fertility-awareness-based method use among women who are currently or will soon be trying to conceive., Objectives: The aim of this study was to identify predictors of fertility-awareness-based methods use among women trying to conceive or contemplating pregnancy within the next year., Methods: Women participating in the Nurses' Health Study 3 were asked if they were trying to become pregnant or contemplating pregnancy and whether they are using fertility-awareness-based methods. Multivariable negative binomial regression was used to identify predictors for a number of fertility-awareness-based methods used., Results: Among the 23,418 women asked about pregnancy intention since 2015, 955 were trying to conceive, and 2,282 were contemplating pregnancy within the next year. The three most used fertility-awareness-based methods among women trying to conceive were menstrual cycle tracking, ovulation prediction kits, and cervical mucus monitoring. Among women contemplating pregnancy, the three most commonly used methods were menstrual cycle tracking, cervical mucus monitoring, and basal body temperature monitoring. The ongoing duration of pregnancy attempts and gravidity were associated with the number of methods used among women actively trying to conceive. When compared with women who were trying for 2 months or less, the number of methods was 29% higher when trying for 3-5 months, 45% higher when trying for 6-12 months, and 38% higher when trying for more than 1 year. Compared with nulligravid women, the number of methods was lower for women with a history of two or more pregnancies. Among women contemplating pregnancy, those who were married or in a domestic partnership used more fertility-awareness-based methods than unpartnered women. No other significant predictors of fertility-awareness-based method use were identified., Discussion: Duration of ongoing pregnancy attempt and gravidity were the only significant predictors for the number of fertility-awareness-based methods used among women actively trying to conceive, whereas partnership was the only significant predictor of the number of fertility-awareness-based methods among women contemplating pregnancy., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Identifying genetic determinants of reproductive success may highlight mechanisms underlying fertility and identify alleles under present-day selection. Using data in 785,604 individuals of European ancestry, we identified 43 genomic loci associated with either number of children ever born (NEB) or childlessness. These loci span diverse aspects of reproductive biology, including puberty timing, age at first birth, sex hormone regulation, endometriosis and age at menopause. Missense variants in ARHGAP27 were associated with higher NEB but shorter reproductive lifespan, suggesting a trade-off at this locus between reproductive ageing and intensity. Other genes implicated by coding variants include PIK3IP1, ZFP82 and LRP4, and our results suggest a new role for the melanocortin 1 receptor (MC1R) in reproductive biology. As NEB is one component of evolutionary fitness, our identified associations indicate loci under present-day natural selection. Integration with data from historical selection scans highlighted an allele in the FADS1/2 gene locus that has been under selection for thousands of years and remains so today. Collectively, our findings demonstrate that a broad range of biological mechanisms contribute to reproductive success., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Study Question: Is adherence to an a priori defined diet quality indices [Alternate Healthy Index 2010 (AHEI-2010), relative Mediterranean diet score (rMED) or dietary approaches to stop hypertension (DASH)] associated with semen quality and reproductive hormone levels in young men?, Summary Answer: Greater adherence to the DASH diet is related to higher sperm counts., What Is Known Already: Studies assessing the relationship between dietary intake and male reproductive function have mainly been focused on specific nutrients, food groups or data-driven dietary patterns, but the evidence on a priori defined dietary indices is still scarce., Study Design, Size, Duration: Cross-sectional study of 209 male university students recruited from October 2010 to November 2011 in Murcia Region (Southern Spain)., Participants/materials, Setting, Methods: Healthy young men aged 18-23 years were included in this study. Diet was assessed using a validated food frequency questionnaire and three a priori-defined dietary indices (AHEI-2010, rMED and DASH) were calculated. Linear regression was used to analyze the relation between the three dietary indices and semen quality parameters and reproductive hormone levels accounting for potential confounders and covariates., Main Results and the Role of Chance: We found statistically significant positive associations between the DASH index and sperm concentration (P, trend = 0.04), total sperm count (P, trend = 0.04) and total motile sperm count (P, trend = 0.02). No associations were observed for other semen parameters or male reproductive hormones., Limitations, Reasons for Caution: Even though we adjusted for several known and suspected confounders we cannot exclude the possibility of residual or unmeasured confounding or chance findings. Subjects were blinded to the study outcomes thus reducing the potential influence on their report of diet. Our sample size may be too small to rule out associations with other semen parameters or reproductive hormones. Causal inference is limited, as usual with all observational studies., Wider Implications of the Findings: The results suggest that greater adherence to the DASH may help improve sperm counts. This study was carried out on young men from the general population. However, results may differ among other populations (e.g. infertile men). Therefore, further research is needed to confirm these findings and extend these results to other populations., Study Funding/competing Interest(s): This work was supported by Fundación Séneca, grants No 08808/PI/08 and No 19443/PI/14; Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III (AES), grants No PI10/00985 and No PI13/01237; and grant P30DK046200 from the National Institutes of Health. Authors have no competing interests to declare., (© The Author(s) 2019. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.)

Benzophenone-3 is used in a variety of cosmetic products as a sunscreen, and has shown weak estrogenic and antiandrogenic activity in animal and in vitro studies. Few studies have evaluated whether benzophenone-3 is associated with reproductive outcomes among women. We studied 304 women undergoing infertility treatment (2007-2017) in the prospective Environment and Reproductive Health cohort study and who underwent 449 treatment cycles (n = 788 urines). Generalized linear mixed models were used with random intercepts to account for multiple cycles, and adjusting for confounders including physical activity. Analyses were also stratified by self-reported moderate/heavy outdoor work. The cycle-specific median (IQR) urinary benzophenone-3 concentration was 147 (58, 462) μg/L, and 98% samples had detectable concentrations. Self-reported sunscreen use, physical activity, and time spent on moderate/heavy outdoor work were positively associated with urinary benzophenone-3. Adjusted probabilities of implantation, clinical pregnancy and live birth were higher in increasing quartiles of benzophenone-3, but these associations were restricted to women who reported spending time outdoors performing moderate/heavy work. Specifically, among these women, those in the highest quartile of benzophenone-3 concentrations had 51% higher implantation (p,trend = 0.02), 68% higher clinical pregnancy (p,trend = 0.01) and 75% higher live birth (p,trend = 0.02) adjusted probabilities than women in the lowest quartile. Benzophenone-3 was unrelated to these outcomes among women who did not report doing moderate/heavy work outdoors. These results confirm that sunscreen use is a source of benzophenone-3 exposure, and show positive associations between benzophenone-3 and pregnancy outcomes, especially among women who reported engaging in outdoor work. Since these associations may be subject to important residual confounding by lifestyle factors, further research is needed to confirm these novel results in other populations, and to investigate whether other factors may be affecting the relation of benzophenone-3 with fertility and other health outcomes., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Context: Marine long-chain omega-3 fatty acids have been positively related to markers of fecundity in both men and women. However, seafood, their primary food source, can also be a source of toxicants, which could counteract the reproductive benefits., Objective: To examine the relationship of male and female seafood intake with time to pregnancy (TTP)., Design: Our prospective cohort study included 501 couples planning pregnancy, who participated in the Longitudinal Investigation of Fertility and the Environment study (2005 to 2009) and were followed up for ≤1 year or until pregnancy was detected. Seafood intake was collected daily during follow-up in journals., Setting: Couples residing in Michigan and Texas were recruited using population-based sampling frameworks., Main Outcome Measures: The primary outcome was the TTP, determined using an in-home pregnancy test. A secondary outcome was sexual intercourse frequency (SIF) as recorded in the daily journals., Results: Couples with male and female partners who consumed eight or more seafood servings per cycle had 47% (95% CI, 7% to 103%) and 60% (95% CI, 15% to 122%) greater fecundity (shorter TTP) than couples with male and female partners who consumed one or fewer seafood servings per cycle. Couples with both partners consuming eight or more seafood servings per cycle had 61% (95% CI, 17% to 122%) greater fecundity than couples consuming less. Male and female partners with the highest seafood intake (eight or more servings per cycle) also had 22% greater SIF., Conclusions: Greater male and female seafood intake was associated with a higher SIF and fecundity among a large prospective cohort of couples attempting pregnancy.

The literature on the relationship between diet and human fertility has greatly expanded over the last decade, resulting in the identification of a few clear patterns. Intake of supplemental folic acid, particularly at doses higher than those recommended for the prevention of neural tube defects, has been consistently related to lower frequency of infertility, lower risk of pregnancy loss, and greater success in infertility treatment. On the other hand and despite promising evidence from animal models, vitamin D does not appear to exert an important role in human fertility in the absence of deficiency. Antioxidant supplementation does not appear to offer any benefits to women undergoing infertility treatment, but it appears to be beneficial when it is the male partner who is supplemented. However, the available evidence does not allow discerning which specific antioxidants, or at which doses, are responsible for this benefit. Long-chain omega-3 fatty acids appear to improve female fertility, although it remains unclear to what extent contamination of shared food sources, such as fish with high levels of environmental toxicants, can dampen this benefit. Lastly, adherence to healthy diets favoring seafood, poultry, whole grains, fruits, and vegetables are related to better fertility in women and better semen quality in men. The cumulative evidence has also piled against popular hypotheses. Dairy and soy, once proposed as reproductive toxicants, have not been consistently related to poor fertility. In fact, soy and soy supplements appear to exert a beneficial effect among women undergoing infertility treatment. Similarly, because data from large, high-quality studies continue to accumulate, the evidence of a potentially deleterious effect of moderate alcohol and caffeine intake on the ability to become pregnant seems less solid than it once did. While a complete picture of the role of nutrition on fertility is far from complete, much progress has been made. The most salient gaps in the current evidence include jointly considering female and male diets and testing the most consistent findings in randomized trials., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: To study whether maternal intake of beverage type affects IVF outcomes., Design: A prospective study., Setting: Tertiary, university-affiliated center., Patient(s): Three hundred forty women undergoing IVF from 2014 through 2016 for infertility as well as for pregenetic diagnosis for autosomal recessive diseases were enrolled during ovarian stimulation and completed a questionnaire describing their usual beverage consumption., Intervention(s): None., Main Outcome Measure(s): IVF outcomes were abstracted from medical records. Total caffeine intake was estimated by summing the caffeine content for specific beverages multiplied by frequency of intake. Associations between specific types of beverages and IVF outcomes were analyzed using Poisson and logistic regression models adjusting for possible confounders., Result(s): Higher intake of sugared soda was associated with lower total, mature, and fertilized oocytes and top-quality embryos after ovarian stimulation. Women who consumed sugared soda had, on average, 1.1 fewer oocytes retrieved, 1.2 fewer mature oocytes retrieved, 0.6 fewer fertilized oocytes, and 0.6 fewer top-quality embryos compared with women who did not consume sugared soda. Furthermore, compared with women who did not drink sugared soda, the adjusted difference in percent of cycles resulting in live birth for women consuming 0.1-1 cups/day and >1 cup/day were -12% and -16%, respectively. No associations were found between consumption of coffee, caffeine, or diet sodas and IVF outcome., Conclusion(s): Sugared beverages, independent of their caffeine content, may be a bigger threat to reproductive success than caffeine and caffeinated beverages without added sugar., (Copyright © 2017 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

Objective This study aimed to examine the relationship between occupational use of high-level disinfectants (HLD) and fecundity among female nurses. Methods Women currently employed outside the home and trying to get pregnant (N=1739) in the Nurses' Health Study 3 cohort (2010-2014) were included in this analysis. Occupational exposure to HLD used to disinfect medical instruments and use of protective equipment (PE) was self-reported on the baseline questionnaire. Every six months thereafter women reported the duration of their ongoing pregnancy attempt. Multivariable accelerated failure time models were used to estimate time ratios (TR) and 95% confidence intervals (95% CI). Results Nurses exposed to HLD prior to and at baseline had a 26% (95% CI 8-47%) and 12% (95% CI -2-28%) longer median duration of pregnancy attempt compared to nurses who were never exposed. Among nurses exposed at baseline to HLD, use of PE attenuated associations with fecundity impairments. Specifically, women using 0, 1, and ≥2 types of PE had 18% (95% CI -7-49%), 16% (95% -3-39%), and 0% (95% -22-28%) longer median durations of pregnancy attempt compared to women who were never exposed. While the use of PE varied greatly by type (9% for respiratory protection to 69% for protective gloves), use of each PE appeared to attenuate the associations of HLD exposure with reduced fecundity. Conclusion Occupational use of HLD is associated with reduced fecundity among nurses, but use of PE appears to attenuate this risk.

Much of the literature on the impact of male caffeine and alcohol intake on reproductive outcomes has utilized semen quality as a proxy for male fertility, although semen parameters have a limited predictive value for spontaneous pregnancy. The objective of this study was to investigate whether male caffeine and alcohol intakes are associated with semen parameters and assisted reproductive technology outcome. The Environment and Reproductive Health Study, an ongoing prospective cohort study, enrolls subfertile couples presenting for treatment at an academic fertility center (2007-2012). A total of 171 men with 338 semen analyses and 205 assisted reproductive technology cycles were included in this analysis. Diet was assessed using a 131-item food frequency questionnaire. Mixed models adjusting for potential confounders were used to evaluate the relationships of male caffeine and alcohol intakes with semen parameters and assisted reproductive technology outcomes. There was no association between male caffeine and alcohol intake and semen quality. Male caffeine intake was negatively related to live birth after assisted reproductive technologies (p-trend < 0.01), and male alcohol intake was positively related to live birth after assisted reproductive technologies (p-trend = 0.04). Adjusted live birth rate among couples with a male partner in the highest quartile of caffeine intake (≥272 mg/day) compared to couples with a male partner in the lowest quartile of intake (<99 mg/day) was 19% vs. 55%, respectively, p < 0.01. In terms of alcohol intake, adjusted live birth rate among couples with a male partner in the highest quartile of alcohol intake (≥22 g/day) compared to couples with a male partner in the lowest quartile of intake (<3 g/day) was 61% vs. 28%, respectively, p = 0.05. In conclusion, male pre-treatment caffeine and alcohol intakes were associated with live birth after assisted reproductive technologies, but not with semen parameters, among fertility patients., (© 2017 American Society of Andrology and European Academy of Andrology.)

Intake of full-fat dairy has been linked to lower semen quality but whether this leads to decreased fertility is unknown. To address this question, we prospectively evaluated the association of men's dairy intake with treatment outcomes of subfertile couples undergoing assisted reproductive technology (ART). We followed 142 men from couples undergoing infertility treatment with ART at an academic fertility centre between 2007 and 2014. Couples completed dietary assessments prior to treatment, and the female partners underwent a total of 248 ART cycles. Multivariable generalized linear mixed models were used to examine the association of dairy intake with fertilization, implantation, clinical pregnancy and live birth rates adjusting for age, body mass index, smoking status, total exercise time, dietary patterns, alcohol, caffeine, total energy intake, and female dairy intake. Intake of dairy foods, regardless of their fat content, was not associated with fertilization, implantation, clinical pregnancy or live birth rates. The adjusted live birth rates (95% confidence interval) for couples in increasing quartiles of men's dairy intake were 0.42 (0.25, 0.60), 0.25 (0.13, 0.42), 0.26 (0.15, 0.41), and 0.44 (0.27, 0.63) (p linear trend = 0.73). Results remained similar after adjustment for female partner intake of dairy foods. Overall, men's dairy intake was not associated with treatment outcomes of couples undergoing ART., (© 2016 American Society of Andrology and European Academy of Andrology.)

Objectives: To evaluate the association of work schedule and physical factors with fecundity., Methods: Women currently employed outside the home and trying to get pregnant (n=1739) in the Nurses' Health Study 3 cohort (2010-2014) were included in this analysis. Work schedule and physical labour were self-reported on the baseline questionnaire, and every 6 months thereafter the women reported the duration of their ongoing pregnancy attempt. Multivariable accelerated failure time models were used to estimate time ratios (TR) and 95% CIs., Results: Among the 1739 women (median age=33 years, 93% Caucasian) the estimated proportions of women not pregnant after 12 and 24 months were 16% and 5%, respectively. None of the various shift work patterns were associated with duration of pregnancy attempt (as a surrogate for fecundity). However, women working >40 h/week had a 20% (95% CI 7 to 35%) longer median duration of pregnancy attempt compared to women working 21-40 h/week (p-trend=0.005). Women whose work entailed heavy lifting or moving (ie, 25+ pounds) >15 times/day also had a longer median duration of pregnancy attempt (adjusted TR=1.49; 95% CI 1.20 to 1.85) compared to women who never lifted or moved heavy loads (p-trend=0.002). The association between heavy moving and lifting and duration of pregnancy attempt was more pronounced among overweight or obese women (body mass index, BMI<25: TR=1.17; 95% CI 0.88 to 1.56; BMI≥25: TR=2.03, 95% CI 1.48 to 2.79; p-interaction=0.007)., Conclusions: Working greater than 40 h per week and greater frequency of lifting or moving a heavy load were associated with reduced fecundity in a cohort of nurses planning pregnancy., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

The role of alcohol on fertility remains unclear. We aimed to investigate the association between alcohol and specific alcoholic beverages consumption and the risk of difficulty getting pregnant. We used a case-control study nested within the Seguimiento Universidad de Navarra (SUN) cohort, a prospective, dynamic and multipurpose cohort of 21,705 Spanish university graduates, followed biennially with mailed questionnaires. We identified 686 case-control pairs, matched for age and time in the cohort. Cases were women reporting difficulty getting pregnant. Controls did not consult due to difficulty conceiving and had at least one child during follow-up. After adjustment for potential confounders, we found no association between self-reported difficulty getting pregnant and the number of alcoholic beverages consumed per week, (Odds Ratio [OR] > 5 drinks/week vs. none = 1.04, 95% Confidence Interval [CI] = 0.72-1.51). No association between types of alcoholic beverage and difficulty conceiving (OR > 5 drinks of wine/week vs. none = 1.16, 95% CI = 0.72-1.88; OR > 5 drinks of beer/week vs. none = 1.06, 95% CI = 0.82-1.37; OR > 5 drinks of spirits/week vs. none = 1.24, 95% CI = 0.84-1.64) was observed. In conclusion, we found no association between alcohol intake and risk of consulting a physician due to difficulty conceiving. More studies are needed to clearly elucidate the effects of alcohol intake on women's fertility. In the meantime, recommendations about alcohol intake to couples trying to conceive have to be given cautiously.

Male factor etiology may be a contributing factor in up to 60% of infertility cases. Dietary intake of phytoestrogens has been related to abnormal semen quality and hormone levels. However, its effect on couple fecundity is still unclear. Intake of soy products was assessed in 184 men from couples undergoing infertility treatment with in vitro fertilization. Couples were recruited between February 2007 and May 2014 and prospectively followed to document treatment outcomes including fertilization, implantation, clinical pregnancy and live birth. Multivariate generalized linear mixed models with random intercepts, binomial distribution and logit link function were used to examine this relation while accounting for repeated treatment cycles and adjusting for potential confounders. Male partner's intake of soy foods and soy isoflavones was unrelated to fertilization rates, the proportions of poor quality embryos, accelerated or slow embryo cleavage rate, and implantation, clinical pregnancy and live birth. The adjusted live birth rates per initiated cycle (95% CI) for partners of men in increasing categories of soy food intake were 0.36 (0.28-0.45), 0.42 (0.29-0.56), 0.36 (0.24-0.51), and 0.37 (0.24-0.52), respectively. Soy food intake in men was not related to clinical outcomes among couples presenting at an infertility clinic. Data on the relation between phytoestrogens and male reproductive potential remain scarce and additional research is required to clarify its role in human reproduction., (© 2015 American Society of Andrology and European Academy of Andrology.)

Objective: To evaluate the use of fertility treatments among a large cohort of women in the United States., Design: Cohort study., Setting: Nurses' Health Study II., Patient(s): Ten thousand thirty-six women who reported having used fertility treatment on biennial questionnaires from 1993-2009., Intervention(s): None., Main Outcome Measure(s): Data on patterns of treatment modality were collected via self-report from validated mailed questionnaires. Information on clomiphene, gonadotropin injections alone, and gonadotropin injections as part of intrauterine insemination (IUI) and in vitro fertilization (IVF) was queried., Result(s): Most women who reported fertility treatment used clomiphene (94%), with a large majority reporting clomiphene as their only form of treatment (73%). Of women who reported treatment more advanced than clomiphene, 13% had used gonadotropin injections alone, 11% IUI treatment, and 11% IVF. Several subgroups were more likely to use multiple treatment modalities and to initiate treatment with gonadotropins rather than clomiphene, including women living in states with insurance coverage of fertility procedures, with higher household income, younger in age, who remained nulliparous at the study close, and treated after 2000., Conclusion(s): Results should be interpreted cautiously, but to our knowledge, this represents the first study of fertility treatment patterns in the United States and could inform public health planning., (Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)