Eating for Two: A Guide to Mother’s Nutrition during Pregnancy

Pregnant woman standing on a scale. Nutrition during pregnancy is important for mom and baby.

During pregnancy, every ounce of baby’s growing body after that very first single cell has come from her mother’s own body. The brain, the heart, the muscles are all built from nutrients that were once part of her mother. The baby is quite literally her flesh-and-blood offspring. Nutrients that Mom eats during pregnancy, or that she has eaten beforehand, are the exclusive fuel and the only raw material building blocks for the baby’s growth. There is nothing else. That is why nutrition during pregnancy is so important. 

This is a special time. A mother and baby together have different nutritional requirements than either of them will ever have alone. Because the mother is the one doing the eating, we’ll look at these needs from the perspective of changes needed in the mother’s diet.

Mother’s Nutrition during Pregnancy

Sadly, nutrition has not been an adequate priority in mainline medicine. We’ve learned a lot about nutrition in recent years, but much of it hasn’t filtered into physicians’ texts, much less popular parenting books. 

Prenatal vitamins are designed with these recommendations in mind. Keep in mind that the handful of vitamins and minerals in the tablets are just the Hollywood stars of nutrition. Each organic whole food contains a cast of thousands of micronutrients that we are just beginning to understand. Some of these important “extras” don’t even have names yet. A diet rich in the variety of organic foods where the “leading actor” nutrients naturally occur is probably the best diet for pregnancy.

The prenatal vitamin can be an important safety net. Getting more of these same nutrients from food is generally great, but taking more of them as supplements is unnecessary and unwise.

Folate and Iron

Out of all the vitamins, minerals, and other nutrients in our diets, we only know of two whose requirements increase by 50 percent or more during pregnancy: one vitamin and one mineral, folate (also known as folic acid) and iron. Deficiency of either folate or iron can lead to anemia in the mother and in the baby.

Famously, the baby uses folate when forming its neural tube, the ancestor to the brain and spinal cord. To do this, adequate supplies of folate are most important at about 21 to 28 days after fertilization. This is the reason that getting plenty of folate surrounding conception can help prevent birth abnormalities called neural tube defects. Women who eat plenty of folate-rich foods can store folate supplies for 2 or 3 months.

What Dad Eats Counts, Too

Dad’s diet, like Mom’s, may help babies before they are even born! Researchers have found that men who take in enough folate may make their offspring less susceptible to later cancer, according to a study published in the February 2001 Fertility and Sterility. For years, women have been encouraged to get enough folate to help prevent birth defects. Now, folate appears to encourage strong, healthy sperm that produces healthier kids. This breakthrough suggests that other choices in Dad’s life not yet studied may also play a role in the strength and vitality of his sperm and the subsequent health of his children.

How Much Folate Do You Need?

Preventing neural tube defects is the poster child for folate supplementation. But folate is also critically important whenever a new copy of DNA is made. Each new cell in the baby’s rapidly growing body requires a new copy of the baby’s DNA. Folate is critical for the process of cell division. It’s a necessary ingredient as the one-celled fertilized eggs divides and divides, again and again, into the trillions of cells present at birth. At about six weeks pregnant, the nervous system alone is adding about 100,000 new nerve cells an hour!

Folate occurs naturally in a variety of foods. Organic green vegetables (especially leafy vegetables), dry beans, peas, and fruits can be great sources for pregnant women. In addition, folate is found in organ meats, such as liver and kidney, although cooking can destroy folate. Clearly, women are adapted to eat larger amounts of at least some of these folate-rich foods during pregnancy. Folate is one important reason for this; there may also be other nutrients in these foods whose requirements we have yet to understand. Perhaps folate is a reason that fruits, fruit juices, and sour foods are so often the foods of pregnancy dreams.

Women who could possibly get pregnant should get at least 400 micrograms of folate per day. During pregnancy, the recommendation increases to at least 600 micrograms per day. A survey of typical American women from 1988 to 1994 estimated an average woman got about 250 micrograms per day in her diet. Those who ate lots of fruits and veggies got more. In 1998, law mandated that enriched cereal grains include folate. Now the typical American adult probably gets about 340 micrograms a day from food.

Prenatal vitamins usually have more folate than other vitamins, giving women who take them plenty of folate with just a little extra help from the diet.

The Gift of Iron

Iron requirements also soar during pregnancy. Both the mother and the baby need it to build red blood cells. A pregnant woman’s blood supply increases by 1/3 over the course of the pregnancy. Babies must grow their entire blood supply from scratch – and scratch includes iron. It’s also a foundational building block of muscles and of a number of enzymes carrying out vital processes throughout the body.

Iron occurs naturally in a number of foods. Good sources include organic fruits and vegetables such as raisins, apricots, prunes (and prune juice), spinach, kale, and other greens. We get it when we eat wonderful legumes such as dried beans, soybeans, peas, and lentils, and grains such as oatmeal. Especially rich sources include meat, fish, poultry, and eggs. Liver tops the list. Clearly, pregnant women are designed to eat more of at least some of these foods. Perhaps it’s one reason why women lay awake dreaming of some of these foods (I can almost smell the juicy cheeseburger with sliced apricots).

A savvy meal planner and smart cookware turn up the heat on getting enough of this important mineral. Eating or drinking foods high in vitamin C (such as orange juice) at the same time as foods high in iron helps the body to absorb and use it well. Cooking in iron pans can also add it to foods.

Many foods, especially cereal grains, are now iron-fortified. It’s poorly absorbed from these sources, but manufacturers have dumped in enough to make up for this. In addition, prenatal vitamins contain plenty of iron.

Pregnant women need about 27 mg of iron per day to supply themselves and their babies. A healthy baby born at term should have a store of about 500 mg of it in her body, all of it a gift from her parents.

Vitamin B6 and Iodine

We only know of two other nutrients whose requirements increase by more than 40 percent during pregnancy. Again, we have one vitamin and one mineral: vitamin B6 and iodine.

Vitamin B6, also called pyridoxine, is actually a group of six closely related compounds. This gang of six are coenzymes in over 100 different important metabolic processes, including the creation of serotonin and other neurotransmitters that help you feel good and think fast. B6 is vital for normal brain and muscle function and is used by the body to help remove unwanted excess metals. Most B6 is stored in muscles, where it can be stored for quite a long time.

Pregnant women need 1.9 mg per day of vitamin B6. Most charts I’ve seen list B6 as occurring primarily in milk, muscle meat and organ meats (liver). It is present in meats, but as with folate, B6 is often destroyed by cooking. Organic milk is a great source!

B6 is also present in large amounts in a great many fruits, vegetables, grains, nuts, seeds, legumes, fish, poultry, and meats. A baked potato has about 0.7 mg after cooking – the same as a raw banana. A half cup of cooked beans has a bit less, but the same amount as half a cooked chicken breast. A 3 oz serving of pork loin has 0.42 mg, about the same amount as avocado, a 12 oz glass of tomato juice, or 2 oz of sunflower seeds. A 3 oz serving of roast beef has about 0.32 mg, about the same as 2 oz of walnuts or 1 cup of spinach.

Typical American women get about 1.4 mg per day from their diets, enough for their non-pregnant needs. Increasing a variety of whole foods should do the trick during pregnancy. Moreover, prenatal vitamins contain plenty of B6.

Iodine is a mineral essential for the normal functioning of the thyroid gland. This is especially important for developing babies because thyroid hormone regulates the developing brain, heart, kidneys, muscles, and pituitary gland. Mothers also need more for themselves during pregnancy.

Iodine occurs abundantly in foods and plants grown in the sea. Even where the sea is now gone, if the soil is rich in iodine, this iodine makes it into plants grown in that soil, and into the milk of cattle fed those plants. Pregnant women are designed to eat at least some of these foods. Today, iodized salt shows up in so many foods that iodine deficiency in pregnancy is unusual.

Zinc

During pregnancy, the only other nutrient whose requirement increases by more than 30 percent is zinc. Zinc is found in almost every cell in the mother’s and the baby’s bodies. The baby needs zinc to support its burgeoning growth and to make each new copy of DNA. Zinc is vital for the newly awakened sense of taste and smell. It supports a healthy immune system and facilitates the body’s repair and remodeling work. Like vitamin B6, it is an active player in over 100 different critical biochemical processes in the body. Low zinc levels can lead to slowed fetal growth and premature deliveries. Pregnancy outcomes, in general, are measurably better when mothers have a healthy amount of zinc.

Most Americans get their zinc from red meat and from poultry. Other rich sources of zinc include beans (baked beans), nuts (cashews, pecans, walnuts, and almonds), seafood (oysters and flounder), whole grains (bran or oatmeal), and dairy products (yogurt and cheese). At least some of the naturally zinc-rich foods belong in a pregnant diet. When it comes to meats, choosing organic  is probably even more important than when it comes to fruits and vegetables.

Pregnant women need at least 11 mg per day. Prenatal vitamins typically contain 15 mg. Zinc is also a common ingredient in fortified cereals.

Omega-3 Fatty Acids

Omega-3 fatty acids are polyunsaturated fats that are literally building blocks of the baby’s developing retinas and brain. It surprises most people, but the brain is about 60 percent fat. Mothers can turn omega-3s into DHA, the premium ingredient now added to a growing number of formulas for babies. DHA crosses the placenta in preference to other similar fatty acids and becomes the primary structural long-chain polyunsaturated fat in the brain – as long as plenty is available. The amount available depends on Mom’s diet. When the supply is lacking, babies assemble their brains from substitute ingredients.

Omega-3’s have many proven benefits in adults, including improved heart health, reduced inflammation, and decreased auto-immune diseases.

Mothers can get what they need in fish, flax seeds, walnuts, vegetable oils (such as canola oil or soybean oil – but not most oils), and to a lesser extent in eggs and meat. Pregnant women need 1.4 grams per day. Ten ounces of salmon and two ounces of walnuts would provide enough omega-3 fatty acids for a pregnant woman for a week. These fatty acids are not present in most prenatal vitamins, but DHA supplements are available. I suspect Omega-3 fatty acids were the main source of my wife Cheryl’s insistent craving for tuna fish sandwiches.

Niacin, Riboflavin, Thiamin and Pantothenic Acid

These are the only remaining nutrients of which we know women need to increase their proportional intake during pregnancy. Pregnant women are designed to eat diets richer in these nutrients. Like all of the nutrients we have covered so far, niacin, riboflavin, thiamine, pantothenic acid and omega-3 fatty acids all need to become bigger parts of the bigger pregnancy diet. Total amounts of other nutrients, such as fiber, selenium, vitamin A, and vitamin C, also need to increase slightly during pregnancy – but not as much as overall calories do.

The words “niacin, riboflavin, thiamin, and pantothenic acid” may make the eyes glaze, or they may sound familiar from the side panel of a cereal box or a package of bread. Because they are so widely supplemented, deficiency is unlikely. They are all coenzymes active in a variety of metabolic processes in both moms and babies.

Niacin occurs naturally in whole grains, legumes, and nuts, as well as in meat, fish, and poultry. Riboflavin shows up in whole grains, as well as in milk, meats, and (again) liver. Thiamin is found predominately in whole grains, but also richly in pork. Pantothenic acid is widely dispersed in whole grains, yeast, potatoes, tomatoes, eggs, broccoli, chicken, beef, and (care to guess?) liver.

These vitamins are all contained in prenatal supplements – unlike the final nutrients on this list.

Not Found in Most Prenatal Vitamins!

Chromium

Chromium is a mineral that works with insulin to maintain normal blood glucose levels. This can be especially important during pregnancy. Only 30 micrograms a day are needed, but many people don’t get enough. Food sources include brewer’s yeast, onions, broccoli, turkey, tomatoes, Romaine lettuce, grape juice, ham, potatoes, green beans, (yes) liver, beef, chicken, oysters, eggs, wheat germ, green peppers, apples, bananas, and spinach.It’s also in butter, molasses, and black pepper. I won’t mention that it’s present in beer, because that’s definitely not for right now! (Except, perhaps, for alcohol-free beer. This still can still have a small amount of alcohol in it – Muslims and liver transplant recipients are urged not to drink it – but the amount of alcohol is similar to the amount in orange juice. It seems fine to me, in moderation, if it doesn’t whet your appetite for the alcoholic variety.)

Chromium is not available in most prenatal vitamins or in most enriched or fortified breads and cereals. A diet rich in whole grains and cereals, however, will probably provide enough chromium.

Calcium!?

My favorite OB textbook says that vitamin D requirements double in pregnancy and that calcium and phosphorous requirements each go up by 50 percent. The latest scientific evidence, however, suggests that requirements for vitamin D, phosphorus, and calcium, don’t go up at all during pregnancy.

It is true that a woman delivers about 25,000 to 30,000 mg of calcium to her baby over the course of pregnancy to build her baby’s bones. If she needs 1,000 mg per day for her own needs, it would seem that she would need more during pregnancy to provide for the extra needs of her baby. But the current recommended amount for pregnant adult women is still 1,000 mg per day.

Research has shown that a woman’s body recognizes the need for the extra calcium and gears up the intestines to absorb a higher proportion of the calcium in the diet. More is absorbed, and more is stored. If women are getting just the routine amount of recommended calcium, pregnancy is a time of calcium feast, not famine.

The problem is that most women do not tend to get the amount they need from what they eat and drink. A glass of organic skim milk has about 300 mg; a cup of organic yogurt about 400 mg, a cup of cooked organic broccoli about 180 mg. Perhaps this is why dairy products appear on so many lists of strongly-desired foods during pregnancy. Calcium-fortified juices and other foods are good alternatives if you need some extra calcium. Prenatal vitamins vary in their calcium content. Most have at least 200 mg – but that still may leave a gaping calcium gap.

Calories

“Eating for two” is an oft-repeated phrase during pregnancy. But when it comes to the additional amount that women need to eat, it is more like eating for 1.1! Okay, for some women, perhaps a bit more – but generally not as high as eating for 1.2. If you would have had a 10-ounce glass of orange juice, now you would want an 11 or maybe 12-ounce glass – not two glasses!

You need an extra 300 calories per day, more or less, to support all of the growth and changes in both mother’s and baby’s bodies. This isn’t much! (An apple has about 120 calories.) And you want these extra calories to be packed with nutrients.

Putting It Together

A prenatal vitamin can be an important safety net, containing most of the vitamins and minerals that we have learned mother and baby need. It can let you relax and enjoy eating, but I wouldn’t let it steer you away from the general type of diet pregnant women are designed to eat.

You can achieve optimum nutrition for mother and baby with a delicious and balanced diet of a variety of organic whole foods. Be sure to enjoy a balance that includes plenty of fruits and vegetable, grains and legumes, as well as lean protein and calcium sources.

This will also leave room for some yummy desserts, and for following some of those intense cravings. If the cravings persist, rescan the list of nutrients in this series, to see if any insight “pops” as to what your baby and your body might be trying to say.

You’ll notice some of the things not found on the list of foods needed in pregnancy: partially hydrogenated oils, high fructose corn syrup, modified food starch, processed white flour, artificial flavors, artificial colors, and chemical preservatives. These are all common in highly processed food products and have become staples of the modern diet.

Some of these may be fine for the baby. But by choosing meals of organic whole foods, or by choosing food products with short ingredient lists that don’t sound like chemistry sets, you will avoid experimenting on your child to find out!

Liver

We’re getting close to the part on chocolate, but first a word about liver. You’ll have noticed that many of the vitamins and elements needed in larger proportions during pregnancy are present in liver. Liver is loaded with iron and folate, the two nutrients at the top of the increased-need-in-pregnancy list. Does this make liver a great choice for pregnancy? The glory of the gestational gourmet?

I think not.

Here’s one good reason. Liver is also loaded with vitamin A. While vitamins are necessary for life, too much of a good thing can be toxic. This is especially true of the fat-soluble vitamins, E, A, D, and K. The requirements for E, D, and K do not go up at all during pregnancy. Slightly more vitamin A is needed – but not as much as the increase in calories. The diet can be proportionally lower in vitamin A during pregnancy.

The recommended daily amount of vitamin A is 770 micrograms (compared to 700 micrograms before pregnancy). This is 2567 IU (international units). Prenatal vitamins often contain about 2700 IU, covering the pregnancy needs.

One study found that pregnant women given more than 10,000 IU a day had double the risks of birth defects. Other studies suggest that up to 25,000 IU may be safe. But all agree that too much vitamin A is toxic. The official upper limit recommended during pregnancy is 10,000 IU per day, including that obtained in food and supplements combined. You are unlikely to get too much from a prenatal vitamin coupled with a normal balanced diet – with one exception.

A single 3-ounce serving of liver can contain up to 30,000 IU of vitamin A! There is no proof that eating liver causes birth defects, but I can’t recommend eating liver regularly during pregnancy. (Nor can I recommend taking extra supplements of the vitamins or minerals found in your prenatal vitamins.) Of course, many pregnant women can’t stomach the sight or smell of liver, no matter how it is prepared.

Chocolate, though, is another story.

Chocolate During Pregnancy

One of the most commonly used pregnancy handouts suggests that women reduce or eliminate chocolate from their diets while pregnant. But chocolate is high on the list of very most desired foods by many pregnant American women. Extremely so. Interestingly, pregnancy chocolate love seems to be less strong in Europe and in many other countries. What’s the story here?

Recent research into dark chocolate has uncovered a variety of health benefits, including lowering blood pressure and raising levels of antioxidants that seem to protect against heart disease, aging, and some cancers. Some research suggests that it can lower “bad” cholesterol, lower weight, and improve the mood.

Perhaps pregnant European women don’t desire chocolate as much because their diets are already higher in beneficial flavenoids and other polyphenols. These compounds are also present in many fruits, vegetables, teas, and red wine (but no wine now!).

Apart from the health benefits of chocolate…

Chocolate Concerns during Pregnancy

Caffeine

We know that too much caffeine is not healthy for mom or baby. Research suggests, though, that low-to-moderate caffeine intake is probably fine. What is a moderate amount of caffeine? The March of Dimes (“When a baby cries, we answer it with research.”) has set their safe level at less than 200 mg per day. A cup of coffee might have 120 mg or so (depending on how it is brewed). A 12-ounce can of Diet Pepsi has 36 mg, Pepsi One has 55.5 mg. A cup of green tea has about 15 mg; hot cocoa has 14 mg; and an ounce of milk chocolate has a caffeine equivalent of about 6 mg. A Hershey bar is 1.55 ounce. Chocolate lovers, do the math.

Heartburn

We know that chocolate contains theobromines, substances that relax the stomach “lid” sphincter that, when tight, helps stop acid from sloshing up to cause heartburn. Later in pregnancy, heartburn is common. Mothers plagued by this may want to do everything they can to tighten that sphincter, even eliminating chocolate. But from my perspective as a pediatrician, they can decide how to balance their own pleasure and pain.

Eating for the Future

With all that we know about tobacco, how can people still smoke?

It’s easy. They’re enticed by big business; they enjoy it; it’s cool; and it’s very, very habit forming. Now for the sobering truth – poor nutritional choices cause every bit as much cancer, death, disability, and chronic disease as cigarettes do. The modern American diet is public health threat number one to our children. With all that we know about junk food, how can people still eat it?

What an opportunity you have! For generations, many parents had no idea that they could start their children on the road to good nutrition before they were even born.

How much better to have a tradition of good nutrition before they meet that onslaught! How much better to support their enjoyment of delicious healthy foods when solid foods are first introduced!

Window of Opportunity

And now is an even more special opportunity. In the womb, your baby’s eyes are shielded from the seduction of commercials, from the kid’s meal toys, and from the group-think of peer pressure. She tastes and remembers what you eat! All she knows is what you feed her in quiet, and what her dad feeds you. She loves what she eats, grows from it now, and develops tastes for the future.

The prenatal vitamin is an important way to fill in the nutrient gaps, but babies were designed to thrive from what mothers ate long before these and other supplements were invented.

When I was growing up, my father grew tomatoes in our backyard. These vine-ripened tomatoes were absolutely delicious – far better than any others I can remember having. As plants grow, the new growth is built from materials taken from the soil. Nothing can be incorporated into plants unless it is present in the soil. Plants grown in depleted soils are just not the same. But plants do the best they can with whatever materials are available. They can do a lot with a little.

You are your baby’s soil.

When you first meet your baby face to face, you’ll be looking at cheeks and toes built from the food you have eaten.

What an opportunity!

Dr. Alan Greene

Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.

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