HMN 2026: How Fathers’ diet before conception could significantly affect fetal growth and placenta development

What fathers eat before conception could significantly influence fetal growth and placenta development, new research in mice suggests. A team of scientists from the University of Sheffield, found that although dietary differences had no major effect on fertility, both high-fat “Western-style” diets and low-protein diets in males altered key biological processes in the placenta after fertilization. The findings, published in eLife, add to growing evidence that paternal health and nutrition before conception may play an important role in early development.

As the placenta regulates the exchange of nutrients between mother and fetus, changes in its development could potentially influence later health. In addition to regulating maternal cardiovascular and metabolic health during pregnancy, poor placental development has been directly linked to serious gestational diseases such as preeclampsia.

The study focused on male mice that were fed different diets for eight weeks before mating. Some received a standard diet, while others were fed a low-protein diet or a high-fat, high-sugar “Western” diet designed to replicate poor quality diets commonly consumed by men worldwide. Additional groups received versions of these diets supplemented with nutrients involved in methyl-donor metabolism, which plays a role in epigenetic regulation.

Despite these dietary differences, the researchers found no major effect on male fertility. However, significant biological changes were observed once pregnancy began.

When the researchers examined placental tissue early in pregnancy, they observed alterations in placental metabolism and structure, particularly in the ectoplacental cone, a region important for early placenta formation. Later in pregnancy, analysis of placental gene activity revealed changes in gene expression patterns linked to the father’s diet.

One striking finding was a change in sex-specific gene activity in the placenta. In pregnancies fathered by males on a standard diet, more than 300 genes showed different activity between male and female placentas. In contrast, when fathers consumed either low-protein or Western-style diets, the number of genes showing these sex differences dropped dramatically.

These findings suggest paternal diet can reshape the normal biological differences between male and female placentas.

Lead researcher, Dr. Adam Watkins, from the University of Sheffield’s School of Medicine and Population Health, said, “We’ve known for a long time that a mother’s diet is the foundation of a healthy pregnancy, but our research suggests that fathers are far from being silent partners in this process. What a man eats in the period leading up to conception may do more than just affect his own health—it could play a key role in shaping the well-being of both his partner and the developing baby.

“While this study was conducted in mice, the fundamental biological blueprints for sperm production and placental function are remarkably similar to our own. While further research in humans is essential to map these specific mechanisms, these findings suggest paternal nutrition is a vital, and often overlooked, piece of the fertility puzzle.”

Dr. Augusto Coppi, Senior Lecturer in Veterinary Anatomy at the University of Bristol, who led the study’s analysis of the placental structure, added, “Using Bristol’s gold-standard 3D quantitative analysis we found molecular shifts occurred without major changes in the placenta’s size or structure late in pregnancy.”

Male mice consuming the Western-style diet also developed features associated with metabolic disruption, including: increased body fat, elevated liver cholesterol and fatty acids, changes in gut microbiota composition.

The research was shaped by individual expertise, while benefiting from collaboration across teams and partners. The team at the University of Sheffield is now hoping to conduct further research in humans in order to turn these findings into practical pre-conception advice, ensuring that preparing for pregnancy becomes a shared health priority for both parents.

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