Many infertility specialists already advise their patients to eat healthy, but the advice primarily focuses on women’s dietary choices.
“Our findings suggest for the first time that future parents are consuming ultra-processed foods” – i.e. women and Male sex is “associated with fertility and early development of offspring,” says study co-author Romy Gaillard, MD, a pediatrician and associate professor of developmental epidemiology at Erasmus University Medical Center in Rotterdam, the Netherlands.
Here, we introduce possible causes of this association and what reproductive endocrinologists want you to keep in mind when it comes to diet during pregnancy.
Study reveals multiple fertility issues caused by ultra-processed foods
Published in a magazine human reproductionThe study analyzed data from about 800 women and 650 male partners who participated in a population-based study that followed parents from conception to pregnancy and into the child’s early childhood.
The researchers collected data on the parents’ diet through a questionnaire completed early in pregnancy (approximately 12 weeks).
The researchers calculated that ultra-processed foods accounted for an average of 22% of the participants’ total daily dietary intake for women and 25% for men.
The survey also asked researchers about how long it took participants to get pregnant, how likely they were to become pregnant within a month, their use of assisted reproductive technology, and infertility, which refers to the inability to conceive within 12 months.
The researchers had access to ultrasound data collected at 7, 9, and 11 weeks of pregnancy. This allowed the researchers to analyze information about the fetus, such as the distance between the fetus’ head and hip (indicating size and development) and the volume of the yolk sac.
Researchers found that for women, eating more ultra-processed foods was not associated with difficulty conceiving, but was associated with slightly smaller fetal growth and yolk sac size by seven weeks of pregnancy. (This may be associated with an increased risk of negative outcomes such as premature birth, low birth weight, and increased risk of miscarriage.)
For men, it was found that eating more ultra-processed foods increased the likelihood of poor fertility.
“These differences are small, but important from a research perspective and at a population level, as the consumption of ultra-processed foods is rapidly increasing around the world,” Dr. Gaillard says.
“Our findings highlight the importance of involving both mothers-to-be and fathers-to-be in preconception counseling, as women’s and men’s health and lifestyle play an important role in reproductive outcomes,” says Gaillard. “If you’re a couple, it’s easier to make sustainable lifestyle changes.”
It is important to note that the participants were relatively healthy, so it is difficult to generalize the results to high-risk groups. The study was also observational, so it’s difficult to say that eating ultra-processed foods directly caused these results. Instead, the findings only show links.
New research confirms previous findings
Josette C. Dawkins, M.D., a reproductive endocrinologist at Boston IVF in Springfield, Massachusetts, says fertility is a complex process, and it’s difficult to say whether diet alone will increase or decrease fertility. But the latest findings mirror previous research linking ultra-processed foods to fertility, she says.
A study published in 2025 found a link between men who ate a diet high in ultra-processed foods and decreased sperm quality and motility, or the ability of sperm to move.
Another observational study published in 2025 found a link between ultra-processed foods and reduced fertility in women, with more than 40 percent of women’s diets coming from this food category.
How does diet affect pregnancy in men and women?
Dietary choices can affect fertility in several ways. “Diet plays an important role in influencing hormone production, egg and sperm quality, and overall reproductive health,” says Dr. Dawkins, who was not involved in the study.
“For men, zinc, antioxidants, and healthy fats improve sperm quality,” she says. “For women, nutrients such as folic acid, vitamin D, and omega-3s support egg quality and hormonal balance, and protect eggs from oxidative stress.”
Eating more ultra-processed foods means people are eating less whole foods that can provide these important nutrients. “Not only do these processed foods promote inflammation, but they are deficient in key antioxidants such as omega-3s, which are important in reducing oxidative stress,” Dawkins says. That can affect sperm DNA and egg quality, she added.
Too much refined sugar, a common feature of many ultra-processed foods, can lead to insulin resistance and hormonal imbalances, says Sara Murkowski, M.D., a reproductive endocrinologist and gynecologist at Ivey Fertility Center Dallas IVF Center in Texas.
“Furthermore, chronic inflammation, which may be a result of continued exposure to ultra-processed foods, may not only make the uterine environment less comfortable, but also impair sperm and egg development,” says Dr. Murkowski, who was not involved in the study. Ultra-processed foods also tend to be low in fiber, which can interfere with gut health, promote inflammation and cause further fertility issues, she added.
Finally, ultra-processed foods can contribute to overweight and obesity, “all of which are accelerated,” says Alex Robles, M.D., a reproductive endocrinologist at the Columbia University Fertility Center in New York City.
More research is needed to determine exactly why ultra-processed foods may affect fertility, Gaillard said.
Why infertility experts value optimal nutrition
“We are what we eat, so it’s important to give our bodies the nutrients they need to function optimally,” says Murkowski. “For my patients who are trying to conceive, I recommend focusing on whole foods and lean proteins, especially those containing omega-3 fatty acids, antioxidants, and high-fiber carbohydrates.”
Dr. Robles says it’s important for both partners to consider diet. “While this study shows an association rather than a cause-and-effect relationship, it supports the importance of a balanced, nutritious diet when trying to conceive,” he says. “Reducing your intake of ultra-processed foods and focusing on minimally processed whole options are practical steps couples can take to support fertility and early pregnancy health.”
Dr. Murkowski says patients don’t need to completely eliminate ultra-processed foods from their diets. Instead, she suggests patients strive to get at least 80 percent of their food intake from minimally processed foods.
“Watch for nutrients like folic acid, vitamin D, antioxidants, and omega-3s,” says Dawkins. “Limit refined sugar, unhealthy fats, and excess alcohol.”
However, fertility experts stress that dietary changes have limited impact on pregnancy. “A healthy diet alone won’t overcome the medical causes of infertility, so consult a fertility specialist in all matters,” says Dr. Dawkins.
