By Dr. Elisa Pérez (Gynaecologist – Reg. No. 203311163).
Human fertility has never been particularly efficient, but the current context has put it under even greater strain. Parenthood is increasingly being postponed, exposure to environmental toxins is higher, and we lead lifestyles that, often without realising it, directly influence our reproductive capacity.
In fact, the World Health Organization (WHO) estimates that 1 in 6 couples experiences reproductive difficulties, a figure that continues to rise. Clearly, there are many factors that can influence infertility, and diet is one of them. Dr Elisa Pérez, Medical Director of IVF-Life Donostia, addressed this topic in a talk held at the GOe – Gastronomy Open Ecosystem in Donostia, where she shared key insights to improve the chances of achieving pregnancy and analysed the current state of fertility.
If we look back, the change is evident. In the 1960s, the average age of women having their first child was around 25, whereas today it exceeds 32. This shift is the result of various social changes, such as women’s integration into the workforce, the search for economic stability, difficulties in finding a stable partner, or the lack of work–life balance.
Added to this is another concerning fact: one in three women believes they can conceive naturally until the age of 45 or later, a perception that does not always align with biological reality. Women are born with approximately two million eggs, which are progressively lost with each menstrual cycle. Therefore, over time, not only does the quantity decrease, but so does egg quality. At the same time, studies show a decline of up to 35% in semen quality over recent decades, confirming that fertility is a matter for both partners.

There is growing scientific evidence that lifestyle habits and diet influence reproductive function. Diets high in saturated fats, refined sugars and ultra-processed foods can promote inflammatory processes and increase oxidative stress, a direct enemy of both eggs and sperm.
Excess body weight also plays an important role, as a high body mass index is associated with poorer egg quality and worse reproductive outcomes. However, not only weight matters, but also fat distribution. In addition, certain micronutrients are essential for fertility:
Nevertheless, it is important to emphasise that this is not about taking supplements indiscriminately, but about maintaining a varied, balanced diet adapted to each individual.
Beyond what we eat, how food is produced, packaged and preserved also matters. Endocrine disruptors are chemical substances capable of interfering with our hormonal system. They are found in plastics, cosmetics, pesticides, hygiene products and industrial pollutants, and exposure to them is constant.
Compounds such as bisphenol A (BPA), phthalates or parabens can affect ovulation, egg quality, the menstrual cycle or embryo implantation. In men, they are associated with alterations in spermatogenesis and damage to sperm DNA. Their effects are cumulative and particularly critical during the prenatal period and childhood.
Reducing their impact involves small everyday actions, such as avoiding heating food in plastic containers, prioritising fresh products, choosing safer cosmetics or reducing the consumption of ultra-processed foods.

In recent years, the intestinal microbiota has gained prominence as a mediator between diet, environment, hormones and fertility. An imbalance in this bacterial flora can influence inflammatory, metabolic and hormonal processes that affect both ovarian function and semen quality.
For this reason, caring for the microbiota means opting for a diet rich in fibre, fruit, vegetables, legumes and fermented foods, as well as avoiding excessive alcohol and sugar intake.
Despite leading a healthy lifestyle, there are situations in which pregnancy does not occur naturally. In these cases, assisted reproduction techniques offer personalised solutions, with treatments ranging from artificial insemination to in vitro fertilisation, using either own eggs or donor eggs.
Currently, 12% of babies born in Spain result from assisted reproduction techniques, a figure that reflects both the scale of the issue and the effectiveness of the available treatments.
In addition, embryonic genetic studies make it possible to identify chromosomally normal embryos and prevent the transmission of known hereditary diseases, increasing success rates and reducing the number of attempts required.