Recent scientific investigations have shed new light on the multifaceted factors influencing reproductive success, moving beyond the traditional singular focus on maternal age. Two distinct studies underscore the significance of both paternal age and dietary practices, specifically time-restricted eating (TRE), in impacting fertility outcomes.

A study published in the journal Human Reproduction, which analyzed 1,712 egg donation cycles in Italy and Spain from 2019 to 2023, revealed a crucial link between advanced paternal age and increased risks in IVF outcomes. Researchers found that when men over the age of 45 were involved in IVF, miscarriage rates (before 24 weeks) significantly increased to 23.8 percent, compared to 16.3 percent for younger paternal age groups. Furthermore, live birth rates were notably lower for older fathers, at 35.1 percent versus 41 percent for men aged 45 or younger, even when young donor eggs were used. This challenges the long-held belief that sperm age has minimal impact post-fertilization. Dr. Maria Cristina Guglielmo, an embryologist at Eugin Italy, highlighted that while maternal age has traditionally been central, these results demonstrate the crucial and independent role of the male partner's age. She attributed this to the continuous division of sperm stem cells as men age, increasing the likelihood of DNA replication errors, which can impair embryo development and elevate miscarriage risk. The findings strongly suggest that fertility clinics should adopt a more balanced approach, ensuring male patients are fully informed about how advancing paternal age can affect fertility potential, pregnancy success, and miscarriage risk during counselling.

Separately, time-restricted eating (TRE), a form of intermittent fasting (IF), has gained attention for its potential impact on fertility, particularly for individuals with polycystic ovary syndrome (PCOS). TRE involves consuming all daily calories within a specific window of hours. A 2025 review in Metabolism Open, examining three studies, indicated that IF could help individuals with PCOS achieve more predictable ovulation schedules, thereby increasing the likelihood of pregnancy. Experts like Dr. Joshua Hurwitz, an OB-GYN and reproductive endocrinologist, note that fasting's ability to aid weight loss can also improve fertility for obese individuals, as obesity-related conditions like hypertension and high cholesterol can negatively affect conception.

Beyond PCOS and weight management, a 2023 study in Free Radical Biology and Medicine observed that one month of alternate-day fasting improved the quality of developing eggs in older mice by lowering free radicals, molecules known to interfere with cellular processes. However, experts like Brittany Brown, RD, caution that this research is preliminary and in mice, stressing the need for more human data before broad recommendations can be made.

Conversely, TRE is not without potential drawbacks. A 2024 study in Cureus Journal of Medical Science highlighted that fasting could lead to nutritional deficiencies, potentially disrupting hormonal balance and decreasing egg quality. As Brown emphasizes, optimal human health is crucial for pregnancy, which can be challenging to achieve during a caloric deficit. Therefore, while TRE may benefit specific populations like those with PCOS (by reducing insulin spikes and managing excess male hormones) or obesity (by promoting weight loss and improving hormone balance), it is not a universal solution.

For the general population, experts such as Mel Spinella, RD, suggest that more traditional approaches like regular exercise and a healthy, balanced diet with nutrient-dense foods consumed throughout the day are generally more effective for maintaining a healthy menstrual cycle and ovulation. Brown also advocates for less restrictive, eat-when-you’re-hungry approaches for those actively trying to conceive, especially as pregnancy becomes possible or confirmed, as reliable and consistent energy intake is essential for reproductive health. The research on fasting and fertility is still in early phases, necessitating large-scale, long-term randomized control trials for a comprehensive understanding of TRE's long-term impacts on fertility.

Regarding fasting schedules, various options exist, from the flexible 14:10 (14 hours fasting, 10 hours eating) to the more restrictive 20:4. While intense schedules like 20:4 may make it difficult to meet daily nutrient needs, a 12:12 approach is often more manageable. Dr. Suzanna Chatterjee, an OB-GYN, specifically recommends a 16:8 schedule for women with PCOS aiming to regulate their cycles. Regardless of the chosen method, medical consultation with a healthcare provider is strongly advised before initiating any fasting regimen, as individual responses vary, and there is no one-size-fits-all approach to fertility journeys.