When you're trying to conceive, it's natural to wonder which foods might be working against you. While there's no need to obsess over every bite, certain foods and eating patterns have been associated with reduced fertility in research studies.
The good news? Most of these foods are also associated with poorer overall health—so limiting them benefits you regardless. And importantly, this isn't about perfection. Occasional indulgences won't derail your fertility. What matters is your overall dietary pattern.
Focus on limiting trans fats (the biggest culprit), reducing added sugars and refined carbs, choosing low-mercury fish, and moderating processed meats. An occasional treat won't hurt—it's your everyday pattern that counts.
Foods with the Strongest Evidence
1. Trans Fats
High ImpactTrans fats have the strongest negative association with fertility of any dietary factor. The Harvard Nurses' Health Study found that for each 2% increase in calories from trans fats (instead of carbs), the risk of ovulatory infertility increased by 73%.
Where they hide:
- Some margarines and shortenings
- Commercially fried foods (some fast food fries, fried chicken)
- Some packaged baked goods (check labels for "partially hydrogenated oils")
- Some microwave popcorn
- Some coffee creamers
How trans fats affect fertility: They interfere with insulin sensitivity, promote inflammation, and may disrupt hormone signaling needed for ovulation.
Use olive oil, avocado oil, or real butter instead of margarine. Choose home-cooked or baked foods over commercially fried items.
2. Refined Carbohydrates & Added Sugars
High ImpactFoods that cause rapid blood sugar spikes trigger insulin release. When insulin is chronically elevated, it can disrupt the hormonal balance needed for regular ovulation—particularly problematic for women with PCOS.
Foods to limit:
- White bread, white rice, white pasta
- Sugary cereals
- Pastries, donuts, cookies, cakes
- Candy and sweetened snacks
- Sweetened beverages (soda, sweet tea, energy drinks)
The research: Women in the highest quintile of glycemic load had a 92% higher risk of ovulatory infertility compared to those in the lowest quintile.
Choose whole grains (brown rice, quinoa, whole wheat), fresh fruit instead of juice or candy, and water or unsweetened beverages.
3. Sugar-Sweetened Beverages
High ImpactSweetened drinks deserve special mention because they're such a concentrated source of sugar with no nutritional benefit. They cause dramatic blood sugar spikes and contribute to insulin resistance.
Research findings:
- One sugary soda per day was associated with 25% lower fecundability (monthly probability of conception)
- This applied to both partners—male soda consumption also reduced couple fertility
- Effects were seen even in women with regular cycles
Water (still or sparkling), unsweetened tea, black coffee, or water infused with fresh fruit.
Foods to Choose Carefully
4. High-Mercury Fish
Moderate ImpactMercury is a neurotoxin that can accumulate in your body and potentially affect fetal development. Large, predatory fish accumulate more mercury. However, don't avoid fish entirely—the omega-3 benefits are important for fertility.
Fish to avoid or limit significantly:
- Shark
- Swordfish
- King mackerel
- Tilefish (from Gulf of Mexico)
- Bigeye tuna
- Marlin
Fish to limit (1-2 servings/week):
- Albacore (white) tuna
- Yellowfin tuna
- Halibut
- Grouper
Salmon, sardines, anchovies, herring, trout, Atlantic mackerel, and light canned tuna are lower in mercury and high in beneficial omega-3s.
5. Processed Meats
Moderate ImpactProcessed meats have been more strongly linked to male fertility issues, though they're best limited for both partners. They're associated with lower sperm quality and may affect female reproductive health as well.
Foods to limit:
- Bacon
- Sausage and hot dogs
- Deli meats and cold cuts
- Ham
- Pepperoni and salami
Why they may affect fertility: Processed meats often contain nitrates, saturated fat, and other compounds that may increase oxidative stress and inflammation.
Fresh poultry, fish, eggs, legumes, or unprocessed red meat in moderation. For sandwiches, try roasted chicken or turkey breast you prepare yourself.
6. Low-Fat Dairy (Surprising!)
Moderate ImpactThis one surprises many people. The Harvard Nurses' Health Study found that women who consumed two or more servings of low-fat dairy daily had an 85% higher risk of ovulatory infertility compared to those who ate it less than once a week.
Meanwhile, one serving of full-fat dairy daily was associated with reduced ovulatory infertility.
Why this might be: The processing that removes fat may also remove fat-soluble hormones and other compounds that support fertility. Or the replacement of fat with other ingredients may be the issue.
Have one serving of full-fat dairy daily: whole milk in your coffee, full-fat Greek yogurt, or regular cheese. You don't need to overdo it—one serving seems to be the sweet spot.
Foods to Be Mindful Of
7. Excessive Caffeine
Low Impact (Moderate Amounts OK)Moderate caffeine consumption (up to 200mg/day—about 1-2 cups of coffee) appears safe when trying to conceive. Higher amounts have been associated with slightly longer time to pregnancy and increased miscarriage risk in some studies.
Caffeine sources to track:
- Coffee (95-200mg per 8oz)
- Tea (25-50mg per 8oz)
- Cola drinks (30-40mg per 12oz)
- Energy drinks (varies widely, often 80-300mg)
- Chocolate (small amounts)
Stick to 200mg or less daily. This is about one 12oz cup of coffee, two cups of black tea, or one small specialty coffee drink. Track your total from all sources.
8. Alcohol
Varies by AmountResearch on alcohol and fertility is mixed. Light drinking (a few drinks per week) hasn't been consistently shown to reduce fertility, but heavier drinking definitely affects it. Once pregnant, no amount of alcohol is considered safe.
What the research shows:
- 14+ drinks/week associated with longer time to pregnancy
- Heavy drinking clearly affects both male and female fertility
- Light drinking (under 7 drinks/week) has inconsistent effects in studies
- During the two-week wait, many experts recommend avoiding alcohol entirely
Many couples choose to limit alcohol while TTC and avoid it completely during the two-week wait. If you drink, keep it to occasional light drinking and consider stopping once you start trying.
9. Unfermented Soy (Maybe)
Unclear EvidenceSoy contains phytoestrogens—plant compounds that weakly mimic estrogen. This has led to concerns about fertility effects. However, research is mixed and moderate soy consumption appears fine for most women.
Considerations:
- Asian populations consuming traditional soy foods don't show reduced fertility
- Fermented soy (tempeh, miso, natto) may be better tolerated
- Highly processed soy (soy protein isolate in many packaged foods) is less studied
- Women with thyroid issues may want to be more cautious
Moderate, whole-food soy (tofu, edamame, tempeh) 2-3 times per week is likely fine. Avoid making soy your primary protein source and limit highly processed soy products.
10. Pesticide-Heavy Produce (Possibly)
Unclear EvidenceSome studies have linked higher pesticide exposure to longer time to pregnancy. However, the benefits of eating fruits and vegetables far outweigh pesticide concerns, so don't avoid produce—just be strategic.
EWG's "Dirty Dozen" (highest pesticide residue):
- Strawberries, spinach, kale
- Nectarines, apples, grapes
- Peaches, cherries, pears
- Tomatoes, celery, peppers
Buy organic when possible for the "Dirty Dozen." Always wash produce thoroughly. Don't reduce vegetable intake due to pesticide fears—the nutritional benefits are too important.
Quick Reference Guide
You don't need to be perfect. Fertility is influenced by your overall dietary pattern, not individual meals or occasional treats. If you're eating well 80-90% of the time, you're doing great.
Stressing about every food choice can actually work against you. Make sustainable changes, enjoy your food, and focus on adding more fertility-supporting foods rather than just eliminating things.
What TO Eat for Fertility
Now that you know what to limit, learn which foods actively support conception.
Read: The Fertility DietThe Bottom Line
The foods with the strongest evidence for negative fertility effects are trans fats, sugar-sweetened beverages, and highly refined carbohydrates. Limiting these—which is good advice for overall health anyway—is a solid starting point.
For everything else, moderation matters more than elimination. High-mercury fish, processed meats, and excessive alcohol or caffeine should be limited but don't need to be completely avoided. Some surprises like the low-fat dairy finding remind us that nutrition science is complex and evolving.
Most importantly, don't let food become a source of stress. Make reasonable choices, focus on eating more whole foods, and trust that your body is resilient. The goal is a sustainable, enjoyable eating pattern—not perfection.