This is a guest post from Chris Kresser of ChrisKresser.com .
As a clinician with a special interest in fertility and pregnancy nutrition, two of the most common questions my patients ask are:
- Is a Paleo/Primal Blueprint diet safe during pregnancy?
- What are the most important foods to eat for boosting fertility and ensuring a healthy pregnancy?
I’m going to answer these questions in this article. But before I do, let’s first take a moment to discuss the importance of proper nutrition for fertility and pregnancy.
Numerous factors determine our health as adults, including nutrition, exercise, lifestyle and genetics. But recent research suggests another powerful influence on lifelong health: our mother’s nutritional status during (and even before) her pregnancy.
In fact, some researchers now believe the 9 months we spend in the womb are the most consequential period of our lives, permanently influencing the wiring of the brain and the function of organs like the heart, liver and pancreas. They also suggest that the conditions we encounter in utero shape everything from our susceptibility to disease, to our appetite and metabolism, to our intelligence and temperament.
We’re only as healthy as our mother’s womb
The theory that the nutritional environment we encounter in the womb determines our lifelong health is known as the Developmental Origins Hypothesis. It was first proposed by British researcher David J. Barker in the 1980s to explain a seeming contradiction: as British prosperity increased, so did heart disease. Yet geographically, the highest rates of heart disease were found in the poorest places in Britain. Barker found that rather than smoking, dietary fat or some other lifestyle cause, the factor that was most predictive of whether an individual would develop premature heart disease (before the age of 65) was their weight at birth  (PDF).
Barker found that infants carried to full term with birth weights between 8.5 and 9.5 pounds had a 45 percent lower risk of developing heart disease later in life than infants born at 5.5 pounds. (They also had a lower risk of stroke, a 70% lower risk of insulin resistance and a slightly lower risk of blood pressure later in life.) As the chart below demonstrates, the risk declined in a linear fashion between 5.5 and 9.5 pounds, but started to increase again as birth weight rose above 9.5 pounds.
How the first nine months shapes the rest of your life
Over the last 25 years, Barker’s original work has been reproduced and expanded. If you do a quick search on PubMed  for “developmental origins of disease”, you’ll find references to the fetal origins of cancer, heart disease, allergies, asthma, autoimmune disease, diabetes, obesity, mental illness and degenerative conditions like arthritis, osteoporosis, dementia and Alzheimer’s.
The following list is just a small sampling of the literature on the subject:
- The metabolic syndrome. In a 2011 paper , Bruce et al showed that the onset of metabolic syndrome is “increasingly likely following exposure to suboptimal nutrition during critical periods of development”.
- Heart disease and diabetes. In a 2002 paper , Barker (the “father” of the Developmental Origins hypothesis) showed that slow growth during fetal life and infancy – itself a consequence of poor maternal nutrition – predisposes individuals to coronary heart disease, type 2 diabetes and hypertension later in life.
- Breast cancer. In a 2006 paper  Hilakivi-Clarke, et al. showed that maternal diet influences the risk of breast cancer by inducing permanent epigenetic changes in the fetus that alter susceptibility to factors that can initiate breast cancer later in life.
- Polycystic ovary syndrome (PCOS). In a 2007 paper , Dumesic et al. showed that insulin resistance and resulting increases of testosterone during pregnancy promotes PCOS during adulthood.
- Obesity. In a 2008 paper  Kalliomaki et al. showed that simply by studying the composition of the maternal gut flora (influenced by nutrition, medications, stress, etc.) they could predict which children will be overweight by age 7!
These studies – and many more – have made it clear that the mother’s nutritional status leading up to and during pregnancy affects her baby’s health not only at birth and during early childhood, but for the rest of his or her life. This leads us to the obvious conclusion that proper maternal nutrition is crucial for boosting fertility and ensuring lifelong health for our children.
But what is proper maternal nutrition? And is the Primal Blueprint diet you’ve come to love safe during pregnancy?
If you listen to the mainstream authorities, they’ll tell you the best diet during pregnancy is one that’s rich in whole grains and low in fat and animal protein. Some of my patients have even been told by their previous physicians or nutritionists that it’s dangerous not to eat grains during pregnancy!
Sound familiar? This is the same misguided advice dietitians have been giving to the general public for decades – and it’s just as wrong for aspiring parents and pregnant moms.
Let’s break out that trusty analytical tool called “common sense” to combat the notion that the Primal Blueprint diet isn’t safe during pregnancy, and that it’s somehow dangerous not to eat grains during pregnancy. If that were true, we wouldn’t even be having this conversation. Why? Because humans have eaten a paleolithic diet (without grains) for the vast majority of our evolutionary history.
Imagine the timeline of human existence as a football field (100 yards from end-zone to end-zone). If you started walking at one end of the field, the first 99.5 yards would represent all of human history up until the last 10,000 years. During those first 77,000 generations of human history, we survived and thrived on a paleolithic diet. It’s only in the last one-half yard that agriculture was developed and humans started regularly consuming grains.
Perhaps the more appropriate question is whether the Standard American Diet is safe. Infertility rates are already high, and they’re increasing at an alarming rate. 1 in 7 women today have trouble conceiving, and a recent study in the U.K. predicted that number could more than double (to 1 in 3) by 2020. While there are probably several reasons for this dramatic increase in infertility, the Standard American Diet is almost certainly one of the most important.
How can you supercharge your fertility and ensure a healthy pregnancy and lifelong health for your baby?
The Primal Blueprint diet is an excellent starting place for those wishing to conceive, or for women who are already pregnant or nursing. But within the context of the Primal Blueprint diet, there are certain foods and nutrients that are particularly beneficial during these periods.
Traditional cultures have known this for millennia. That’s why they have sacred fertility foods they feed to mothers-to-be and even fathers-to-be. These include nutrient dense foods like fish eggs, liver, bone marrow, egg yolks and other animal fats. For example, the Masai tribe in Africa only allowed couples to marry and become pregnant after spending several months drinking milk in the wet season when the grass is lush and the nutrient content of the milk is especially high.
With this in mind, here are the top 5 “superfoods” I recommend for fertility, pregnancy and breastfeeding.
- Liver. Ounce for ounce, liver is one of the most nutrient-dense foods on the planet. It’s loaded with fat soluble vitamins like retinol (pre-formed vitamin A) that are crucial for reproductive health, and difficult to obtain elsewhere in the diet. Liver is also a great source of highly absorbable iron, which helps prevent miscarriage and maternal anemia, and B12, which is required for proper formation of red blood cells and DNA. Liver is also a good source of bioavailable protein, zinc, and folate.
- Egg yolks. Like liver, egg yolks could be considered “nature’s multivitamin”. But they are especially rich in a nutrient many people have never heard of: choline. Studies suggest that 86% of women don’t get enough choline in their diet. This is significant because choline helps protect against neural tube defects. It also plays an important role in brain development, helping to form cholinergic neurons and the connections between these neurons that are so crucial in the first few years of life.
- Cold-water, fatty fish*. Seafood is the exclusive food source of the long-chain omega-3 fats EPA and DHA. DHA is particularly important for fertility and pregnancy. It is preferentially incorporated into the rapidly developing brain during pregnancy and the first two years of infancy, concentrating in the grey matter and eyes. It’s also crucial to the formation of neurons, which are the functional cells in the brain, and to protecting the brain from oxidative damage. Salmon, mackerel, herring and sardines are excellent sources of DHA.
- Cod liver oil. Yep, grandma was right! Cod liver oil is a sacred fertility and pregnancy food that fell out of favor during the last couple of generations, but is making a comeback. It’s one of the highest dietary sources of vitamin A, which we discussed above. It has more vitamin D per unit weight than any other food. Vitamin D is crucial to fertility and pregnancy, and studies show that up to 50% of women are deficient in it. Vitamin D promotes proper development of the bones, especially during the 3rd trimester when the fetal skeleton begins to grow rapidly. Cod liver oil is also a good source of the long-chain omega-3 fats EPA and DHA.
- Grass-fed dairy. While dairy is not strictly a Primal food, it’s a great choice for fertility and pregnancy for those who tolerate it well. Dairy is rich in saturated fat, which is especially beneficial for fertility. It’s also a good source of the fat-soluble vitamins (A, D, K2 & E) and a healthy, natural trans-fat (not to be confused with artificial trans-fats, which are harmful) conjugated linoleic acid (CLA). Fermented dairy products – like yogurt and kefir – are also great sources of beneficial bacteria. This is important because a baby’s first exposure to bacteria is in his/her mother’s birth canal, and the mother’s gut health has a significant influence on the lifelong health of her baby.
*Some women are scared to eat fish during pregnancy because of concerns about mercury levels. It turns out those concerns have been overblown. Read this article  for more information.
Want to supercharge your fertility and promote lifelong health for your baby? Check out the Healthy Baby Code .