Epigenetics: you can change baby’s DNA during pregnancy


By Michael Roizen, M.D., and Mehmet Oz, M.D.

There’s nothing quite like the emotional juxtaposition of pregnancy. On one hand, you’re thrilled, elated, and impatient for your baby’s first smile, babble, and hug. On the other hand, you may feel anxious about a million unknowns—about what’s going on inside your belly, about whether your little one is growing properly, about how you’re going to function on zero sleep.

As you balance these competing emotions, we have one word for you—relax! The most important thing to keep in mind is this: Most pregnancies turn out fine—most being defined as more than 99.5% for mom and more than 95% for babies delivered after 28 weeks. Absolutely fine. Women’s bodies are designed to carry children safely and effectively. That doesn’t mean everything will be smooth sailing on this journey, but it does mean that the odds are greatly in your favor. If you can learn how to maximize your chances that nature runs the course it’s supposed to, then you increase those odds even further.

We’re here to help

We’re here to help you explore the biology of pregnancy and give you the strategies and tips that will help you manage everything from conception to delivery (even from three months before to one month beyond). Of all the things we want you to learn, one of the most important involve a topic that you may have never spent much time thinking about: epigenetics. We know you’re thinking, What on earth is epigenetics?

Baby’s road map

Epigenetics explores what makes us develop in certain ways—why some people thrive while others are prone to chronic diseases. Turns out, there are easy things you can do to help not just your baby’s development in utero, but his opportunity to live a healthy, fulfilling adult life.

Back in 10th grade biology, you were probably taught—as were we—that the unique combination of genes you received from your mom and dad were responsible for everything that followed—the color of your eyes, the size of your feet, your love of lasagna, your hatred for eight-legged creatures. To a certain extent, that’s true, but over the past few years we’ve discovered that classical genetics is only part of your baby’s picture.

Consider identical twins. They get dealt exactly the same DNA, but they may develop different traits down the line: One may have allergies and the other may not, one may develop a particular disease and the other may not, one may be able to play the piano without ever learning how to read music, while the other can’t carry a tune. What accounts for these differences? Something in their environment—potentially as early as in utero—affected the expression of their genes differently. That something is called epigenetics.

Sorting it out

Here’s how it works: Let’s say that you and your partner each come to your relationship with a set of favorite family recipes. You may contribute a blue-ribbon chili recipe to the table, and your significant other may bring a killer lemon meringue pie. But it’s not just two recipes, it’s hundreds, maybe thousands. Some on index cards, some in books, some on torn-up shreds of cocktail napkins. So what do you do with all these cranberry-mold recipes? Stuff each and every one of them in the kitchen drawer. Now it’s hard to sift through them, you don’t have access to many of them, and you really can’t find what you want. Unless—you knew there was an “unless” coming—you get them organized, say, by sticking hot pink notes on the recipes you really want to access quickly. You tag your favorite recipes, so you can quickly search, find, and put them into action.

Genes are like recipes. They’re instructions to build something. Both mom and dad contribute a copy of their entire recipe book to their offspring, but for many genes, only one copy of each recipe will be used by the baby. Mom and dad have the same recipes (one for eye color, one for hair color, and so on), except they may have slightly different versions of those recipes; these are called alleles.

For example, eye genes are either brown or blue or green, etc. For such genes, you express only the gene from your mom or dad—that is, only one copy is active, but not both. In some cases, neither copy will need to be expressed: Eye color only matters to eye cells; a liver cell doesn’t need either mom’s or dad’s eye-color gene to be cranking away. So how does a cell turn off the 24,999 genes it doesn’t need and turn on the few it does?

Every cell—and there are around 200 different types in the body—needs to know which few genes are relevant to it, and, of those genes, whether mom’s or dad’s will be expressed. As with the kitchen drawer full of recipes, the genes alone are useless unless there’s a way for your body to find what you need, when you need it.

You can change your baby’s DNA during pregnancy

Your body puts biological Post-it notes, called epigenetic tags, on certain genes to determine which genetic recipes get used, but guess what? Actions you take during your pregnancy—through nutrition and other behaviors—can influence these processes and determine where the notes go and which genes will be expressed, ultimately affecting the health of your child.

At any given time, only 4% of your genes are in this accessible state, while the rest can’t be actively used in the body. By determining which genes are turned off and which are turned on, epigenetics is what makes you unique.

The way epigenetics works during pregnancy is that stressors in the mother’s environment cause a change in the gene expression patterns of the fetus. Translation: The chemicals your baby is exposed to in utero via the foods you eat, the paint fumes you may breathe in, and the cigarettes you don’t inhale serve as biological light switches in his development. On, off, on, off—you decide how your child’s genes are expressed, even as early as conception. You don’t have total control, though. We still don’t know how you can change your baby’s eye color or if he’ll go bald at age 35. But we do know how to influence some really important factors, such as your child’s weight and intelligence.

Four ways to take action

The environment that you provide your offspring—through eating, drinking, smoking, or stressing—is what your child will program herself to expect of the world she’s entering. Here are some things you can do to positively influence the way your baby’s genes are expressed.

Add folate now. Your baby needs the nutrient folate because it has a direct effect on DNA. Folate is an essential ingredient for one of the building blocks of DNA, thiamine. Without folate, the fetus may substitute a less-effective backup building block called uracil, which can cause birth defects, primarily spina bifida. Also, a lack of folate has been shown to increase childhood cancer rates by more than 60 percent. If you’re even thinking about getting pregnant or are newly pregnant, supplement your diet with 400 micrograms of folic acid every day.

Squash the radiation. To protect your baby from the toxic effects of radiation, you should avoid X-rays and other forms of radiation—like large doses of microwaves or extensive airline travel—during pregnancy. Radiation alters the DNA of cells as they replicate, which is why it’s used in cancer therapy (cancers reproduce faster than regular cells). Fetal cells reproduce the fastest and are the most susceptible to injury, which may lead to miscarriage or birth defects, or predispose your child to cancer later in life. And consider this: Flying for 30 hours results in the same radiation exposure as one chest X-ray. You don’t have to cancel all flights, but it’s worth thinking about whether each trip you are planning can wait.

See the dentist. You’re more likely to be thinking about your appointments with your ob/gyn than you are with your dentist. But you should get your teeth cared for and cavities filled six months before you become pregnant, ideally. While you’re pregnant, maintain your schedule of regular checkups for dental health (but skip the X-rays). Try to wait to get any new cavities filled until after your baby is born, unless the procedure is absolutely necessary. Traditional fillings contain mercury, which release mercury vapor that you absorb; and even composite dental materials have been associated with releasing toxins called phthalates when they harden. Even though no conclusive studies link fillings to fetal-health abnormalities, one may surmise that these chemicals may be harmful to a developing fetus.

Trash those toxins: Stop smoking immediately and avoid second-hand smoke. And take a 40-week break from happy hour, or even longer if you’re nursing. Smoke, alcohol, or harsh chemical cleaners won’t do your baby—or you—any good during this delicate time. But you knew that already.

Be positive. Your baby deserves all the good vibes you can muster up. He’s going to have a great life, thanks to the steps you’re taking!

By Michael Roizen, M.D., and Mehmet Oz, M.D.
authors of YOU: Having a Baby: The Owner’s Manual to a Happy and Healthy Pregnancy
Illustration by Aaron Bihari

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