Background: The mean age for women giving birth to their first child is increasing globally, with few therapeutic options to counteract an age-related decline in female fertility. This study aimed to investigate the effect of dietary micronutrient supplements on spontaneous pregnancy rates in women of advanced reproductive age with infertility of unknown etiology. Materials & methods: This was a retrospective, comparative study of 270 infertile women aged 35-40 years with non-pathological fertility work-up and normal male partner semen analysis attending a fertility clinic in Vienna, Austria. 146 women received an oral micronutrient preparation (omega-3 fatty acids, coenzyme Q10, vitamin E, folic acid, selenium, catechins and glycyrrhizin) daily for 6 months and subsequent monthly rates of spontaneous clinical pregnancy were compared to a control group of 124 women receiving only daily folic acid supplements. No other fertility-related interventions took place during the observation period. Results: The total spontaneous pregnancy rate after 6 months was significantly higher in the study group, reaching 43.8%, compared to 29.8% in the control group (p p = 0.018). Moreover, the cumulative pregnancy rate in the study group taking micronutrient supplementation was 54.5%, and 34.1% in the control group. Conclusions: The findings of this study suggest that the intake of specific micronutrients might be associated with a higher occurrence of spontaneous pregnancies and thus improvement in female fertility among women of advanced reproductive age who experience unexplained infertility. (c) 2024 Elsevier Espana, a, S.L.U. All rights are reserved, including those for text and data mining, AI training, and similar technologies.