According to Holistic Fertility Doctor, Dr. Aumatma Shah, ND, most recurrent miscarriage cases in her practice are linked to nutritional factors. These may include elevated oxidative stress, poor blood sugar control, and high homocysteine in either prospective parent. 

While there are limited clinical studies regarding food, fertility, and miscarriage, nutrition does indeed affect fertility and your odds of carrying a pregnancy full-term. Also, if you haven’t looked into eating more healthfully, it can make a big difference in terms of conception, pregnancy, and fetal health.  

In this article, we’ll explore different nutritional factors that can affect fertility and keeping a pregnancy. Then, we’ll cover how you can eat better to maximize your chance of a successful pregnancy.

According to a study of 17544 women, diet is the most significant independent risk factor (greater than BMI or physical activity) for ovulatory infertility ¹. Another Spanish study demonstrated an almost 45% lower risk for medical interventions for infertility with a Mediterranean-style diet compared to a Western diet ². 

Nutritional needs are necessarily individual depending on your genes, environment, and health status. Here are some of the factors to consider if you’re trying to conceive.

Nutritional factors that may contribute to infertility, pregnancy complications and miscarriage

Insulin resistance, high insulin levels, and high blood sugar

Women with recurrent miscarriages are more likely to have insulin resistance during the first week of pregnancy ³. Elevated insulin levels are harmful to the first-trimester placenta and can increase DNA damage and cell death. The early pregnancy trophoblasts, which are part of the placenta, are very sensitive to high insulin levels ⁴. 

Also, polycystic ovarian syndrome (PCOS) is the most common endocrine disorder that can lead to infertility, miscarriage, and other pregnancy complications. High insulin and insulin resistance are key features of PCOS, although you can have insulin resistance without having PCOS ⁵⁶.

Researchers are still trying to fully understand why insulin resistance increases the risk of miscarriage. However, we know that insulin resistance can contribute to ⁷:

• A hypercoagulable state, which increases the risk of blood clots
• Hormone imbalances as insulin resistance in women can increase testosterone levels 
• Increased plasma homocysteine, which can increase blood clots and reduce blood flow to the uterine lining. It can also affect sperm quality and DNA methylation. 
• Increased free radicals, which can cause DNA damage in both eggs and sperms.
• Abnormal uterine lining development during early pregnancy

Aside from miscarriage, insulin resistance and poor blood sugar control can be harmful to pregnancy. That’s because pregnancy raises blood sugar even in nondiabetic women, which is why some nondiabetic women develop gestational diabetes. 

As pregnancy progresses, insulin resistance naturally increases. There is a 2 to 18 percent chance that pregnant women may develop gestational diabetes, depending on demographic, genetics, health status, and a few other factors. Apart from gestational diabetes, pre-existing diabetes may be present or worsen in many pregnant women ⁸. 

High blood sugar is a significant cause of fetal and maternal pregnancy complications even without pre-existing diabetes ⁹. These complications may include:

• Premature delivery (before 37 weeks)
• Increased fetal growth and large babies (macrosomia)
• Difficult childbirth
• Pre-eclampsia and eclampsia
• Pregnancy-induced hypertension
• Elevated liver enzymes
• Hypoglycemia (low blood sugar), which can worsen morning sickness

According to the CDC, 1 in 3 Americans have prediabetes and even more of them have subclinical insulin resistance or elevated insulin. 8 in 10 prediabetics don’t know they have it. Perhaps even more Americans have subclinical insulin resistance and poor blood sugar control ¹⁰. 

Therefore, it is a good idea to test for blood sugar and insulin resistance, and address it nutritionally when you’re trying to conceive. 

The reference ranges are typically based on 95% of the healthy population. It’s a range that doctors typically rely on to diagnose diseases. However, if you’re close to the high end of these normal ranges, it’s likely you’re developing some insulin sensitivity. Whereas, preventive medicine and functional medicine doctors may prefer that you work towards the optimal ranges, which correspond with the lowest all-cause mortality and best health outcomes. 

Lab tests related to blood sugar and insulin sensitivity

Test name	Abbreviation	Reference range	Optimal range	References
Fasting blood glucose/Fasting glucose	FBG or FPG	70 – 105 mg/dL  3.9 – 5.8 mmol/L	85 –  99 mg/dL 4.7 – 5.6 mmol/L	11
Random blood glucose		Under 140 mg/dL 7.8 mmol/L	Under 120 mg/dL6.6 mmol/L	1213
Hemoglobin A1c	HbA1c	Below 5.7%	Below 5.3%	1415
Fasting insulin		2 – 20 mIU/L	<8	1617
Homeostatic Model Assessment for Insulin Resistance	HOMA-IR (Fasting insulin miU/L x fasting glucose (nmol/L)/22.5 Or (Fasting insulin miU/L x fasting glucose (mg/dL)/405	<2.6	<1	181920
Fructosamine		200 – 285 mmol/L		21

High oxidative stress

Oxidative molecules can damage DNA, lowering the quality of eggs and sperms. Therefore, oxidative stress is one of the leading contributors to infertility and miscarriage ²²²³.  

Males with decreased sperm motility tend to have higher levels of reactive oxygen species in their semen ²⁴ . 

Oxidative stress also affects the quality of the eggs, and higher levels of reactive oxygen species impair the eggs’ maturation. Alcohol consumption and cigarette smoking may impair your fertility by increasing ROS levels ²⁵. 

Nowadays, many people have elevated oxidative stress because of the following: ²⁶

1. Low dietary antioxidants, especially due to lack of colorful vegetables and fruits
2. Insulin resistance and poor blood sugar control
3. Exposure to toxic pollution, pesticides, and endocrine disruptors
4. Refined and processed diet high in fried foods and sugar
5. Medication use, especially on an ongoing basis
6. Alcohol and smoking
7. Sedentary lifestyle
8. Mental/emotional stress and lack of stress management skills
9. Poor quality sleep
10. Infections and dysbiosis
11. Inflammation from food, such as food allergies, intolerance, and sensitivity
12. Excessive stimulant use, including caffeine

Also, as you age, your cells have less capacity to neutralize these antioxidants. It’s one of the reasons fertility declines and miscarriage risk increases with age. 

Fortunately, you can mitigate many of these lifestyle factors by minimizing your toxic exposure, living a healthier lifestyle, and eating more vegetables and fruits. 

Exercise does increase oxidative stress during and a few hours after it’s done. However, in the long term, exercise increases your body’s ability to counteract lifestyle-related oxidative stress. Both a sedentary lifestyle and too much exercise can increase baseline oxidative stress. Generally, you want to continue exercising but not over-exercise. 

Research shows that antioxidant supplements such as CoQ10, vitamin E, and selenium are beneficial for fertility and miscarriage in both prospective parents ²⁷²⁸.  

Lab tests for oxidative stress

Some people prefer to use lab test results to track their progress. We recommend working with an integrative reproductive medicine specialist to run and interpret these tests. 

Commercially available lab tests for oxidative stress include plasma or urine thiobarbituric acid-reacting substances (TBARS), urinary malondialdehyde, and urinary 8-hydroxyguanosine (8-OHdG). These are generally not diagnostic tests but may indicate if you have unaddressed sources of oxidative stress. If these numbers go down after making some changes along with improved markers of egg or sperm quality, then you’re making changes in the right direction.

Studies show that having high levels of these markers correlates with poor sperm quality and sperm abnormalities ²⁹. In women, higher oxidative stress predicts a longer time to conception and a higher risk of pregnancy complications ³⁰.  

Folate deficiency and homocysteine

Homocysteine is a toxic sulfur-containing byproduct of the amino acid methionine. Low vitamin B12 and folic acid, high dietary methionine, and insulin resistance can increase homocysteine ³¹.

High homocysteine and/or folate deficiency can cause miscarriage, placental abruption, and pre-eclampsia. Folate deficiency can also cause neural tube defects. 

Because studies have been mixed on homocysteine, it’s typically not tested as part of miscarriage workup. However, many doctors find that testing and reducing homocysteine whether with diet or supplementation improves conception and pregnancy outcomes. 

To learn more about homocysteine, including reference ranges, see our homocysteine article. Also, consider testing for your MTHFR gene as it may relate to homocysteine and miscarriage.

Typically, taking folate, vitamin B6, and vitamin B12 can reduce homocysteine. Some doctors may also prescribe anti-clotting medications for women with high homocysteine and a history of miscarriage during early pregnancy. Protein sources that are higher in glycine and serine, such as collagen, bone broth, and organ meat may also help with high homocysteine ³²³³.

Vitamin B6 deficiency

A Chinese epidemiologic study looked at 364 textile workers and found that women with higher vitamin B6 levels were 50% less likely to miscarry and had 120% higher fertility ³⁴

This is because a vitamin B6 deficiency can disrupt egg production, fertilization, and embryo development before implantation. In men, a vitamin B6 deficiency can affect sperm production ³⁵³⁶.

During pregnancy, vitamin B6 is important for:

• Red blood cell production, so a vitamin B6 deficiency may also cause anemia during pregnancy ³⁷. 
• Fetal brain and nervous system development
• Normalizing the mother’s neurotransmitter function and may help with morning sickness ³⁸
• Preventing preeclampsia and preterm birth ³⁹. 
• Oral health, as a vitamin B6 deficiency may also worsen pregnancy-associated gingivitis and other dental issues ⁴⁰.

Therefore, you should include foods that are high in vitamin B6 as well as ensure that your prenatal multivitamin contains enough vitamin B6.

Alcohol

Alcohol is generally unhealthy and can be harmful to the fetus, so you may wish to avoid it entirely during pregnancy. However, a drink here and there is generally safe.

Even moderate drinking can throw off hormones and affect your fertility. It stimulates the stress response axis, increasing cortisol. Also, it can throw off the sex hormone axis in both genders ⁴¹. Alcohol can also cause blood sugar imbalances and increase oxidative stress, both of which can lower your chance of getting pregnant and carrying to term. Not surprisingly, moderate to heavy drinking can increase the risk of miscarriage and breast cancer ⁴². 

High alcohol consumption in women increases FSH and LH, while lowering progesterone, thus reducing the chance of successful implantation. In a study of 430 women 20 – 35 years old, even 5 or less drinks per week was associated with reduced fertility ⁴³. 

In men, high alcohol consumption can lower sperm volume, count, motility, and overall number of healthy sperms ⁴⁴.  Therefore, alcohol use can make it more difficult to conceive and increases the risk of miscarriage. Heavy alcohol use is associated with irregular menses, anovulation, luteal phase defects, and early menopause ⁴⁵. 

Should you eat differently with IVF pregnancy vs natural pregnancy?

Your nutritional needs are not different during IVF or an IVF pregnancy vs natural pregnancy. You want to continue with a healthy diet and also avoid risky foods listed above.

Eating more antioxidants, plants, and good fats, such as following a Mediterranean-style diet during IVF may increase your prospects of having a successful pregnancy. It also increases your chances of giving birth to a live baby after undergoing IVF ⁴⁶. 

As with natural pregnancy, avoid alcoholic beverages while undergoing IVF too. A study suggests consuming alcoholic drinks (four per week) may decrease the live birth rate of IVF ⁴⁷. 

How to eat for best chances of conception and successful pregnancy

Many health issues associated with infertility and miscarriage relate to the standard American diet and lifestyle. The good news is that any improvement from that can improve your overall health and chances of a successful pregnancy, whether you identify with a dietary philosophy or not.

These improvements can include:

1. Eating more whole and unprocessed foods, fruits, and vegetables
2. Learning to cook at home and purchasing kitchen tools that facilitate it
3. Eating better quality meat, produce, and fats
4. Increasing the nutrient density of your diet by eating more organ meats and dark color vegetables
5. Paying attention to what you eat and how it affects your body
6. Reducing or avoiding refined sugar and processed foods
7. Learning about food-related inflammation and autoimmunity, and removing them from your diet

Should couples try the Paleo diet fertility and pregnancy?

The Paleo diet philosophy believes that we should eat what hunter-gatherers ate thousands of years ago, before domesticated grains, legumes, and dairy were available. The diet includes meat, seafood, fruits, vegetables, nuts, and seeds. It avoids vegetable seed oils, all grains, especially gluten-containing ones, along with legumes and dairy. However, some Paleo eaters bring back some gluten-free grains, legumes, and dairy if these foods don’t cause them inflammation.

The Paleo diet and lifestyle provide many health improvements that can boost your chance of a successful pregnancy. First, you’ll be eating whole and nutrient-dense foods, focusing more on food quality, and cutting out refined sugar and processed foods. That will make it necessary for you to learn to shop for groceries and cook at home. Many new Paleo eaters notice inflammation going down in their bodies so they feel better. 

Many also lose weight in the process as avoiding processed foods and eating more whole foods causes them to eat fewer calories. However, it’s possible to stay the same or even gain weight on a Paleo diet. 

Although the diet doesn’t define a specific macronutrient ratio, it tends to be lower in carbohydrate than the standard American diet. The Paleo-compliant carbohydrates also tend to be cellular carbohydrates, which are within plant cell walls and take longer to get absorbed. For example, these carbs may include sweet potatoes, plantains, fruits, and root vegetables. You’ll also eat more proteins and fibers. So, overall, the Paleo diet is friendlier to your blood sugar and can help reverse insulin resistance ⁴⁸. 

The Paleo diet is higher in good fats, fat-soluble nutrients, plant-based antioxidants, and vitamins and minerals. At the same time, it’s lower in pesticides and hormone disruptors. These are generally good for fertility and pregnancy. Many women need to consume enough carbs to maintain healthy hormone levels for fertility, and it’s possible to do so with whole food sources of carbs on a Paleo diet.

The Paleo and ancestral diets are fairly simple approaches that focus on real, whole foods and eliminate highly processed foods that may be harmful to fertility. 

Can a gluten-free diet help with fertility and miscarriage?

The answer is that it depends. Gluten sensitivity and Celiac disease have both genetic and environmental components. If you have either of these or get any inflammation from gluten, then it’s a good idea to avoid gluten. 

Gluten is a sticky protein that can be inflammatory. It can cause leaky gut and contribute to autoimmunity in susceptible people. Many parts of gluten are similar to our own proteins, so a dysfunctional immune system can attack gluten and also mistakenly attack our own cells. 

Certain causes of miscarriage and infertility relate to inflammation and autoimmunity. If this is the case for you, then avoiding gluten can be beneficial. Ovarian dysfunction and premature ovarian failure are linked to different autoimmune diseases, including celiac disease ⁴⁹⁵⁰.

Unmanaged celiac disease is also linked to miscarriage and pregnancy complications ⁵¹. If you have one autoimmune condition, you’re much more likely to have another one because you have both the genes, immune dysfunction, and environmental factors that cause autoimmune conditions. 

Women with celiac disease on a gluten-free diet had a lower incidence of spontaneous miscarriage than those on a normal diet. They also had improved fertility. Furthermore, having a gluten-free diet with celiac disease will result in fewer symptoms during pregnancy. Also, you will have a better nourished baby ⁵²⁵³. 

The clinical evidence for removing gluten for infertility and miscarriage is limited. However, many of our medical review board members and colleagues have found that removing gluten and other inflammatory foods was beneficial. 

Given that removing gluten is a low-risk dietary changes, trying a gluten-free diet is worthwhile if you’ve been struggling with repeat miscarriage and fertility issues.

Can avoiding dairy help with fertility and miscarriage?

For most people, dairy can be a healthful and nutritious food. In a systematic review that analyzed 17 clinical studies, milk consumption during pregnancy was associated with infant birth weight and length. There are not enough studies to conclude whether dairy affect any risk of preterm delivery, spontaneous miscarriage, and lactation ⁵⁴. However, dairy tends to contain hormones, whether added or naturally occurring, that may not be beneficial for fertility. So, according to Dr. Simmons, many couples find that their fertility improves after removing dairy. 

In the Fertility Diet study, which followed 18,555 couples for 8 years, consuming a lot of low-fat dairy was found to increase the risk of anovulatory infertility. Whereas, eating high-fat dairy products may decrease this risk. Therefore, high-fat dairy consumption appears to be beneficial for fertility ⁵⁵.

There are, however, a few exceptions where avoiding dairy may be beneficial. Keep in mind that the evidence on the effects of dairy exclusion on fertility and miscarriage is very limited.

Lactose intolerance, dairy allergy, and casein intolerance

Lactose intolerance refers to the inability to digest lactose, a sugar found in milk. This can cause digestive symptoms such as flatulence, gas, bloating, and diarrhea. If you have lactose intolerance, you may need to avoid dairy or consume lactose-free products.

Dairy allergy is a type of food allergy to a protein in milk. Symptoms can range from skin itchiness, eczema, hives, and vomiting to wheezing, airway closure, and anaphylaxis. If you have a dairy allergy, then consuming dairy is most likely unsafe during preconception and pregnancy.

Casein and other types of dairy intolerance

Like gluten, casein is a difficult-to-digest protein, so casein tends to be partially digested. These partially digested fragments of casein can be inflammatory. Particularly, A1 cow’s milk which has an amino acid change so that the fragments are more similar to opioids. They can bind to opioid receptors in the gut and cause digestive problems. Also this fragment is linked to increased risk of cardiovascular disease, type 1 diabetes, and sudden infant death syndrome ⁵⁶.

On the other hand, A2 cow’s milk, and milk from goat, sheep, camel, donkey, and yaks don’t have the same amino acid change. They are therefore less inflammatory. Many people who don’t tolerate A1 milk do tolerate A2 milk. 

As a general rule, if dairy causes any unpleasant symptoms such as digestive problems or mucus buildup, it’s causing inflammation. However, if the symptoms are mild, occasional consumption may be safe. 

Pre-existing autoimmunity and inflammation from leaky gut

Dairy also contains protease inhibitors which can cause leaky gut. Since mammalian mothers transmit immune protection to the baby through milk, it makes sense that the milk causes leaky gut. This allows the newborn to absorb antibodies and other protective molecules from the mother’s immune system ⁵⁷. 

In adults with pre-existing inflammation and autoimmunity, however, the increased intestinal permeability can worsen the inflammation. 

Gluten intolerance or celiac disease

About half the people who are gluten-intolerant or celiac are also sensitive to dairy because the gluten and dairy have similar parts that their immune system recognizes. Therefore, if you have gluten sensitivity, celiac disease, or other autoimmune conditions, you may find that inflammation goes down after removing dairy ⁵⁸.

Insulin resistance

Dairy is a strong stimulator of insulin production, even though it is not a high-carbohydrate food. Therefore, it can contribute to insulin resistance or worsen pre-existing insulin resistance ⁵⁹.  

There is some suggestive evidence that dairy consumption, especially low-fat, can contribute to anovulatory infertility and PCOS ⁶⁰⁶¹. The risk/benefit of avoiding dairy is individual so you should speak to your doctor to determine if avoiding dairy may be beneficial for you.

How to successfully improve your diet

Making major dietary changes and trying to eat healthier can be daunting especially if you’re also feeding your partner and children. You don’t want to rely on discipline and willpower when you and your loved ones are hungry. 

The good news is that eating healthily doesn’t have to be difficult or time-consuming! Planning and preparing ahead are key. So, I created PrepDish, a meal plan subscription service that can help you save time and headaches, whether you simply want to eat healthier, or try a low-carb or Paleo diet. 

For under $3/week, PrepDish meal plans help you efficiently grocery shop once a week and prepare a week’s worth of healthy meals in under an hour. 

PrepDish comes with:

• Weekly shopping list
• Delicious recipes and food prep instructions
• 4 healthy weekly meal plan options for gluten-free, Paleo, low-carb, or super fast meal preps