A new study looked at what nearly 2,600 American women ate and whether they had trouble getting pregnant. Researchers found that women who ate a lot of ultra-processed foods (like packaged snacks and fast food) were less likely to be able to conceive, while women who followed a Mediterranean diet (lots of vegetables, fish, and olive oil) had better fertility outcomes. The study suggests that the quality of food we eat may play an important role in reproductive health, though more research is needed to fully understand this connection.
The Quick Take
- What they studied: Whether eating ultra-processed foods or following a Mediterranean diet affects a woman’s ability to get pregnant
- Who participated: 2,582 American women between ages 20 and 45 who were part of a national health survey from 2013-2018
- Key finding: Women who ate more ultra-processed foods had significantly lower chances of being able to conceive compared to women who ate less of these foods. Women eating Mediterranean-style diets (rich in vegetables, fish, and healthy oils) showed better fertility outcomes, though weight played a role in this relationship.
- What it means for you: If you’re trying to get pregnant or planning to, eating fewer processed foods and more whole foods like vegetables, fish, and olive oil may help. However, this study shows a connection, not proof that diet causes fertility changes, so talk to your doctor about your specific situation.
The Research Details
Researchers used information from a large national health survey that tracked what Americans eat. They looked at data from women aged 20-45 collected between 2013 and 2018. Each woman reported what she ate over two different days, and researchers classified foods as either ultra-processed (heavily manufactured with added ingredients) or whole foods. They also scored how closely each woman followed a Mediterranean diet pattern. The study then compared women who reported having trouble getting pregnant (trying for at least 12 months without success) to women who didn’t have fertility problems.
The researchers used statistical methods to look for patterns between diet and fertility, while accounting for other factors that might affect fertility like age, income, exercise, smoking, and weight. This approach helps them understand whether diet itself matters or if other factors are responsible for the differences they see.
This study design is useful because it looks at real-world eating patterns in a large group of American women, rather than a small lab experiment. By examining actual dietary data and fertility outcomes together, researchers can spot connections that might help women make better food choices. However, this type of study can only show that two things are related—it can’t prove that one causes the other.
The study’s strengths include a large sample size of over 2,500 women and the use of detailed dietary information from a nationally representative survey. The researchers also adjusted their analysis for many other factors that could affect fertility. However, because women self-reported their fertility status, there may be some inaccuracy. Additionally, the study only captured what women ate on two days, which may not represent their typical eating patterns. The study is also observational, meaning it shows associations but cannot prove cause-and-effect relationships.
What the Results Show
On average, women in the study got about 27% of their daily food intake from ultra-processed foods. Women who reported infertility problems ate significantly more ultra-processed foods and had lower Mediterranean diet scores compared to women without fertility issues. When researchers looked at the numbers more carefully, they found that women with higher ultra-processed food intake had much lower odds of being able to conceive—specifically, the odds were about one-third as high compared to women eating less processed food.
For the Mediterranean diet, women who followed it more closely initially showed better fertility outcomes. However, when the researchers adjusted their analysis to account for body weight, this benefit largely disappeared. This suggests that the benefit of the Mediterranean diet might work partly through helping women maintain a healthier weight, which itself supports fertility.
The study found that women reporting infertility had notably different eating patterns overall. They consumed more ultra-processed foods and fewer foods typical of the Mediterranean diet. The average Mediterranean diet score among all women was quite low (3.35 out of 8), suggesting that most American women in the study weren’t following this eating pattern very closely. This finding highlights that dietary patterns in the U.S. may not be optimized for reproductive health.
Previous research has shown that diet affects fertility in both men and women, but most studies focused on specific nutrients rather than overall eating patterns. This study adds to that body of knowledge by looking at how ultra-processed foods specifically relate to fertility, and by examining a whole dietary pattern (Mediterranean diet) rather than individual foods. The findings align with other research showing that processed foods may harm reproductive health, though the specific mechanisms aren’t yet fully understood.
This study has several important limitations. First, it’s observational, meaning it can show that two things are related but cannot prove that one causes the other. Women self-reported whether they had fertility problems, which may not be completely accurate. The dietary information came from only two days of eating records, which may not represent what women typically eat. Additionally, the study couldn’t determine whether women had medical fertility problems or simply hadn’t tried to conceive yet. Finally, the study only included American women, so results may not apply to women in other countries with different food systems and dietary patterns.
The Bottom Line
If you’re trying to get pregnant or planning to, consider reducing ultra-processed foods and eating more whole foods like vegetables, fruits, fish, whole grains, and healthy oils (like olive oil). This recommendation has moderate support from this research. However, diet is just one factor affecting fertility—other important factors include age, overall health, stress, exercise, and medical conditions. Talk to your doctor or a registered dietitian for personalized advice about your diet and fertility.
This research is most relevant for women of reproductive age (20-45 years old) who are trying to get pregnant or planning to in the future. It may also interest women concerned about their overall health, since ultra-processed foods are linked to many health problems beyond fertility. However, if you have diagnosed fertility problems, you should work with a fertility specialist rather than relying only on diet changes.
If you change your diet, you shouldn’t expect immediate changes in fertility. It typically takes several months of consistent healthy eating to see effects on reproductive health. Most fertility experts recommend making dietary changes at least 2-3 months before trying to conceive, as this allows time for the changes to affect egg quality and overall reproductive function.
Want to Apply This Research?
- Track the percentage of your daily food intake that comes from ultra-processed foods versus whole foods. Aim to reduce ultra-processed foods from the typical 27% to below 15% of your daily intake, and log this weekly.
- Replace one ultra-processed food item you eat daily with a whole food alternative. For example, swap packaged snacks for fresh fruit, or replace sugary drinks with water. Use the app to log this swap and track consistency over time.
- Create a weekly Mediterranean diet score by tracking how many days you eat fish, vegetables, whole grains, and use olive oil. Aim to increase this score from the average of 3.35 toward a goal of 6 or higher out of 8. Monitor trends over 8-12 weeks to see if dietary changes correlate with how you feel and other health markers.
This research shows an association between diet and fertility but does not prove that changing your diet will improve fertility. Fertility is complex and influenced by many factors including age, medical conditions, genetics, and lifestyle. If you’re having trouble conceiving, consult with a healthcare provider or fertility specialist for proper evaluation and personalized treatment. This information is for educational purposes and should not replace professional medical advice. Always discuss dietary changes with your doctor, especially if you’re trying to conceive or have underlying health conditions.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.