Could Your Diet Influence Embryo Development Before You Even Know You’re Pregnant?

New Research Raises Important Questions About Ultra-Processed Foods and Early Pregnancy Development

By Emanuela Lazzaroni, MS

Senior Embryologist, ESSI Fertility & Immunology

Reviewed by the ESSI Editorial Team · internationalendo.com

When discussing infertility, most conversations focus on embryo quality, ovarian reserve, sperm parameters, endometriosis, adenomyosis, implantation, or immune dysfunction. Nutrition is often viewed as an important component of overall health, but its role in reproductive outcomes remains an area of active investigation.

A recently published 2026 study in Human Reproduction has added an interesting new perspective to this discussion by examining whether the consumption of ultra-processed foods during the months surrounding conception may be associated with fertility and early embryonic development.

The findings do not prove that diet causes infertility or alters embryo development. However, they raise important questions about how the preconception environment may relate to the earliest stages of pregnancy.

Why the Earliest Weeks Matter

As embryologists, we often focus on events that occur inside the IVF laboratory—fertilization, cleavage, blastocyst development, embryo grading, and preimplantation genetic testing (PGT) results. Yet, some of the most critical events in human development occur during the earliest weeks after conception inside the maternal tract.

Before many women even realize they are pregnant, cells are rapidly dividing, developmental pathways are being activated, and the cellular foundations of placental development are beginning to form. This period represents one of the most dynamic and sensitive stages of human development.

Researchers continue to investigate how factors such as genetics, metabolic health, inflammation, environmental exposures, and nutrition may influence this early developmental environment.

What Are Ultra-Processed Foods?

Ultra-processed foods (UPFs) are industrially manufactured products that typically undergo multiple stages of processing and often contain additives, preservatives, artificial flavorings, emulsifiers, and refined ingredients.

Common examples found in modern diets include:

• Sugary breakfast cereals

• Packaged snack foods and chips

• Soft drinks and artificially sweetened beverages

• Fast food products

• Processed meats (such as sausages and deli meats)

• Commercial desserts and packaged baked goods

• Many ready-to-eat frozen or shelf-stable meals

These foods have become a major part of modern diets and have been systematically associated with a variety of systemic health concerns, including obesity, metabolic disease, and chronic inflammation.

Because metabolic and inflammatory pathways are also known to play important roles in reproductive health, researchers have become increasingly interested in studying whether these specific dietary patterns may cross over to influence fertility and early pregnancy outcomes.

What Did the Study Investigate?

The investigators executed a prospective cohort study following more than 800 women and over 600 male partners from the preconception period through early pregnancy.

The investigators rigorously evaluated dietary intake before conception and examined its relationship to:

• Overall fertility outcomes

• Time to pregnancy (TTP)

• Absolute risk of subfertility

• Early embryonic growth

• Yolk sac development during the first trimester

One of the unique strengths of this study was its precise focus on the periconceptional window—the period immediately surrounding conception. This window is notoriously difficult to capture in human clinical trials but is highly relevant to reproductive biology and epigenetic programming.

What Did the Researchers Find?

Among the women tracked, higher consumption of ultra-processed foods was associated with differences in certain early pregnancy ultrasound measurements.

Specifically, researchers observed statistically significant associations between higher maternal intake of ultra-processed foods and:

• Smaller embryonic growth measurements

• Smaller yolk sac volume during early pregnancy

Interestingly, these structural differences were most noticeable around seven weeks of gestation and became less pronounced later in the first trimester.

The Role of the Yolk Sac

The yolk sac is one of the earliest structures visible during an early pregnancy scan. It plays an indispensable role in supporting the developing embryo—serving as the primary site of hematopoiesis (blood cell production) and nutrient transfer—before the placenta becomes fully functional.

While the exact clinical significance of these subtle variations remains an area of ongoing study, these observations suggest that the nutritional environment surrounding conception may warp early morphological development.

Why Is This Study Interesting to Reproductive Science?

Much of traditional fertility research focuses entirely on macro-outcomes: Did fertilization occur? Did the embryo form a blastocyst? Did it implant? Did it result in a live birth?

This study looked at something much more nuanced. Rather than focusing or conditioning exclusively on whether a pregnancy successfully occurred, the researchers examined the kinetics and quality of development happening during the earliest, quietest stages of embryonic life after conception.

Although the study’s observational nature means it cannot definitively establish direct cause and effect, it contributes to a growing, sophisticated body of research exploring how lifestyle factors and the metabolic environment before pregnancy may be associated with reproductive outcomes. For fertility patients, this expands the conversation beyond pregnancy rates alone and encourages us to look at the biological environment in which early cellular development occurs.

Relevance to the ESSI Community

Patients facing infertility or complex reproductive disorders frequently want to know whether there are factors within their immediate control that may help support their reproductive health.

While nutrition is an adjunct and is unlikely to overcome major, structural reproductive challenges—such as embryo aneuploidy (genetic abnormalities), advanced maternal age, severe deep infiltrating endometriosis, dense adenomyosis, diminished ovarian reserve, or mechanical tubal disease—it remains an important variable that influences the body’s overall systemic environment.

[ 📸 INSERT IMAGE 3 HERE: An infographic detailing the “ESSI Integrated Care Paradigm,” showing how medical/surgical treatments reset structural issues (like endometriosis or adenomyosis) while lifestyle adjustments optimize the cellular baseline. ]

This study did not specifically evaluate patients with endometriosis, recurrent implantation failure, or active IVF cycles. However, it adds valuable insight to the broader scientific discussion regarding how preconception health and lifestyle factors modify reproductive biology. As our understanding of fertility continues to evolve, studies such as this help us move away from a reductionist view of fertility and identify new, multi-system areas for future research.

What Should Patients Take Away?

The most important clinical message is that this study does not prove that ultra-processed foods cause infertility or directly damage embryo development. It is an observational cohort study, meaning it identifies statistical associations rather than direct, linear causation.

However, it does provide compelling evidence that dietary patterns before conception may interact with certain aspects of early pregnancy development.

For individuals preparing for conception, entering an IVF cycle, or recovering from reproductive surgery, focusing on a balanced diet rich in whole, nutrient-dense foods while limiting highly processed products remains a highly reasonable, low-risk approach for supporting overall health. Whether nutrition directly alters early embryonic development remains an area of ongoing investigation, but studies such as this remind us that reproductive health begins long before a positive pregnancy test.

REFERENCE

• Lin CHX, Gaillard R, Mulders AGMGJ, Jaddoe VWV, Schipper MC, et al. Periconceptional ultra-processed food consumption in women and men, fertility, and early embryonic development. Human Reproduction. 2026;41(5):722–735.

• Original Article: Human Reproduction Database / Oxford Academic

TALK TO THE ESSI FERTILITY & SURGICAL TEAM

• At ESSI, we treat the whole patient. If you are preparing for fertility treatments, navigating recurrent pregnancy loss, or seeking advanced excision surgery for endometriosis or adenomyosis, our world-class multidisciplinary team is here to help you optimize every layer of your reproductive health.

• Learn more about our integrated clinical care at internationalendo.com.

METHODOLOGY NOTE: Physician and embryologist commentary in this article reflects the editorial position of the ESSI scientific team based on the cited literature. Statements are clinical opinion intended for educational purposes and do not constitute individualized medical advice. Patients should discuss their personal metabolic, nutritional, and reproductive profiles with their treating physician.