A Dutch study of 831 women and 651 male partners linked higher male ultra-processed food intake with lower fecundability.
In women, higher intake was associated with smaller early embryonic measurements and yolk-sac volume, highlighting nutrition as a shared consideration.
When couples prepare for pregnancy, it is often the woman's diet that changes first: less coffee, supplements and foods thought to support conception. What about her partner?
A burger on the way home, instant noodles at night or habitual packaged snacks can seem unrelated to pregnancy planning.
Research suggests, however, that what the male partner usually eats may also be associated with a couple's chance of conception.
A study by Erasmus University Medical Center researchers, published in Human Reproduction, found that higher male consumption of ultra-processed foods was associated with lower fecundability.
In women, higher consumption was associated with smaller early embryonic size and yolk-sac volume.
Male intake and time to pregnancy
The researchers analyzed data from 831 women and 651 male partners participating in the Dutch Generation R Study Next birth cohort.
Dietary assessments were used to calculate the proportion of total food intake classified as ultra-processed, and the team examined its relationship with time to pregnancy.
For each one-standard-deviation increase in male intake, the fecundability ratio, reflecting the relative monthly chance of conception, was approximately 10% lower. The odds of subfertility, defined as taking at least 12 months to conceive or using assisted reproduction, were approximately 36% higher.
Analyses accounted for male age, body mass index, smoking, alcohol consumption and education, as well as the female partner's ultra-processed food intake.
This suggests an association with the couple's conception chances beyond the woman's dietary pattern. However, 36% higher odds do not mean that the actual probability of subfertility increased by 36%.
Female intake and early embryonic development
A somewhat different pattern appeared in women. Intake was not clearly associated with fecundability, but differences were observed in early developmental measurements.
Ultrasound examinations at 7, 9 and 11 weeks measured crown–rump length, the distance from the embryo's head to its bottom, and yolk-sac volume.
Higher intake was associated with relatively smaller embryonic length and yolk-sac volume at 7 weeks. These associations weakened at 9 and 11 weeks.
The yolk sac supports nutrition and early development, making its development one of the features assessed in early pregnancy.
The study did not establish whether the observed size differences lead to miscarriage or health problems after birth.
What counts as ultra-processed food?
The term does not cover every food that has been cooked or processed. It generally refers to industrial formulations involving multiple processing steps, refined ingredients and various additives.
Examples include some processed meats, packaged snacks, soft drinks, ready meals and mass-produced snack products. Not all ham or bread belongs in the same category; ingredients and manufacturing methods matter.
The researchers considered several possible explanations for the associations.
Diets dominated by these products may provide less fiber and fewer essential nutrients, while some products are high in sugar or saturated fat. These nutritional characteristics could potentially influence sperm production and function.
Some endocrine-disrupting chemicals associated with food packaging were also proposed as possible contributors.
The study did not directly demonstrate sperm injury. It remains unclear whether nutrients, additives, packaging exposures or other factors explain the associations.
Pregnancy preparation is not solely the woman's responsibility
The differing findings in women and men are important.
Male intake was associated with time to pregnancy, whereas female intake was associated with early embryonic developmental measurements.
This suggests that attention to nutrition before pregnancy should include both partners.
It does not mean that eating ultra-processed foods inevitably causes infertility or that stopping them will improve conception chances. This observational study identified associations, not direct causation.
A separate systematic review and meta-analysis published in 2026 did not find a statistically robust association between ultra-processed food intake and infertility. With few studies and considerable variation between results, further validation was needed.
What should couples preparing for IVF take from this?
How should couples considering IVF or intrauterine insemination interpret the study?
It examined conception and early development in a general-population cohort. It did not directly test whether reducing ultra-processed foods improves IVF fertilization, implantation or live-birth rates.
Rather than expecting dietary change alone to resolve infertility, couples can use the findings as an opportunity to review overall nutritional balance and lifestyle together.
The tendency to place responsibility for preconception nutrition only on women also deserves reconsideration. Male partners are equally relevant to reproductive health.
Preparing for pregnancy is not a task for the woman alone. Paying attention to everyday shared meals matters alongside attending medical appointments together.
Couples with suspected infertility or delayed conception should not rely on dietary management alone; specialist consultation and appropriate investigations remain important.
Source: This article is based on “Periconceptional ultra-processed food consumption in women and men, fertility, and early embryonic development,” published online in Human Reproduction on March 24, 2026, and in the May issue, volume 41(5), pages 722–732. Celine H. X. Lin, Romy Gaillard, Annemarie G. M. G. J. Mulders and colleagues at Erasmus University Medical Center analyzed dietary and pregnancy data from 831 women and 651 male partners recruited in 2017–2021. DOI: 10.1093/humrep/deag023; PMID: 41871947.
Image disclosure: The image was created using generative AI (ChatGPT, OpenAI). The people shown are fictional, not real individuals.
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