Adherence to healthy dietary patterns and outcomes of assisted reproduction: a systematic review and meta-analysis

Adherence to dietary recommendations mediates the effect of affective temperaments on infertility treatment outcomes

Affective temperaments have been shown to robustly affect infertility treatment success. However, identification of possible mediating factors through which they exert their influence is still lacking. A growing number of results suggest that adherence to recommended treatments may be such a mediator, on the one hand, because affective temperaments are known to influence adherence and, on the other hand, because non-adherence negatively influences the treatment outcome. Recommended treatment of infertility involves, beyond medications, dietary and lifestyle changes. The aim of this retrospective cohort study was to evaluate whether adherence to physician-prescribed diet and physical activity recommendations mediates the effect of affective temperaments on infertility treatment outcomes. Among 308 women who underwent infertility treatment in an Assisted Reproduction Center, affective temperaments, adherence to diet, adherence to physical exercise, and infertility treatment success (clinical pregnancy) were assessed besides detailed medical history and demographic parameters. Associations between affective temperaments, adherence to diet and recommended physical activity, and assisted reproduction outcomes were analyzed using generalized linear models and causal mediation analysis. Adherence to physical activity didn't have an effect, but diet adherence increased the odds of infertility treatment success by 130% suggesting its role as a potential mediator. Based on causal mediation analysis, higher depressive and anxious temperament scores were directly associated with 63% and 45% lower odds of achieving clinical pregnancy, respectively, with effects not mediated by diet adherence. Higher irritable temperament scores indirectly decreased the odds of achieving clinical pregnancy by 14%, mediated by diet adherence; while higher cyclothymic temperament scores decreased the odds of achieving clinical pregnancy both directly by 51% and indirectly, mediated by diet adherence by 11%. Our results suggest that diet adherence mediates the mechanism by which irritable and cyclothymic affective temperaments influence IVF treatment success. Since adherence is a modifiable risk factor of infertility treatment success, screening for affective temperaments may help to identify potentially high-risk non-adherent patient groups and offer patient-tailored treatment, which may help increase the chances of a successful pregnancy and live birth in women undergoing IVF treatment.

Can Dietary Patterns Impact Fertility Outcomes? A Systematic Review and Meta-Analysis

There are conflicting results on the effect of diet on fertility. This study aimed to assess the effect of different dietary patterns on fertility outcomes in populations who conceive spontaneously and those requiring assisted reproductive technology (ART). A systematic search and meta-analysis were performed for studies investigating dietary patterns or whole diets in reproductive aged women requiring ART or conceived naturally. Outcomes were live births, pregnancy rates and infertility rates. In amount of 15,396 studies were screened with 11 eligible studies. Ten different diet patterns were grouped broadly into categories: Mediterranean, Healthy or Unhealthy. For the Mediterranean diet, on excluding high risk-of-bias studies (n = 3), higher adherence was associated with improved live birth/pregnancy rates in ART [OR 1.91 (95% CI 1.14-3.19, I² 43%)] (n = 2). Adherence to various Healthy diets was associated with improved ART outcomes (ProFertility diet and Dutch Dietary Guidelines) and natural conception outcomes (Fertility diet). However, due to the variability in Healthy diets' components, results were not pooled. Studies demonstrated preliminary evidence for the role of dietary patterns or whole diets in improving pregnancy and live birth rates. However, due to heterogeneity across the literature it is currently unclear which diet patterns are associated with improvements in fertility and ART outcomes.

Anti-Inflammatory Diets in Fertility: An Evidence Review

Infertility is a global health concern affecting 48 million couples and 186 million individuals worldwide. Infertility creates a significant economic and social burden for couples who wish to conceive and has been associated with suboptimal lifestyle factors, including poor diet and physical inactivity. Modifying preconception nutrition to better adhere with Food-Based Dietary Guidelines (FBDGs) is a non-invasive and potentially effective means for improving fertility outcomes. While several dietary patterns have been associated with fertility outcomes, the mechanistic links between diet and infertility remain unclear. A key mechanism outlined in the literature relates to the adverse effects of inflammation on fertility, potentially contributing to irregular menstrual cyclicity, implantation failure, and other negative reproductive sequelae. Therefore, dietary interventions which act to reduce inflammation may improve fertility outcomes. This review consistently shows that adherence to anti-inflammatory diets such as the Mediterranean diet (specifically, increased intake of monounsaturated and n-3 polyunsaturated fatty acids, flavonoids, and reduced intake of red and processed meat) improves fertility, assisted reproductive technology (ART) success, and sperm quality in men. Therefore, integration of anti-inflammatory dietary patterns as low-risk adjunctive fertility treatments may improve fertility partially or fully and reduce the need for prolonged or intensive pharmacological or surgical interventions.