Ultra-processed foods and male fertility: A new study has found that eating more ultra-processed foods may be linked to lower fertility in men, slower early embryo growth, and smaller yolk sacs, which play an important role in early pregnancy development.
Researchers said ultra-processed foods are now a regular part of many people’s diets, but their possible effect on fertility and very early human development has not been well understood. Dr Romy Gaillard, lead researcher and associate professor of developmental epidemiology at Erasmus University Medical Center in Rotterdam, said there has been little evidence so far on how both parents’ intake of these foods may affect the time it takes to conceive and early embryo development.
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The study, published in Human Reproduction, analysed data from 831 women and 651 male partners who were part of the Generation R Study Next Programme, a long-running population-based study following parents from before conception into their children’s early years. The couples joined the study either before pregnancy or during pregnancy between 2017 and 2021.
Researchers gathered information on diet and time to pregnancy through questionnaires. They also looked at fecundability, meaning the chance of conceiving within one month, and subfertility, defined as taking 12 months or longer to conceive or needing assisted reproductive technology.
To assess early development, the team measured embryo size and yolk sac volume through transvaginal ultrasounds at seven, nine and 11 weeks of pregnancy. On average, ultra-processed foods made up 22 per cent of women’s total food intake and 25 per cent of men’s intake.
The study found that women’s intake of ultra-processed foods was not consistently linked with subfertility or a longer time to conceive. However, it was associated with slightly smaller embryo growth and smaller yolk sac size by the seventh week of pregnancy.
First author Celine Lin, a PhD student at Erasmus University Medical Center, said the differences seen in early development were small, but still important from both a research and public health perspective. She said the findings suggest that ultra-processed food intake may matter not only for the mother’s health, but also for the baby’s earliest stages of development.
Among men, higher intake of ultra-processed foods was linked to a greater risk of subfertility and a longer time to achieve pregnancy. However, it was not linked to differences in early embryo development.
Lin said this may be because sperm are especially sensitive to diet, while the mother’s diet may directly shape the environment in the womb from the very beginning of life.
Gaillard said the findings suggest that both partners may benefit from eating fewer ultra-processed foods, not only for their own health but also to improve their chances of conception and support healthy early development of the baby.