Pregnancy and genes image Our genes, inherited from our parents, are essentially fixed for life. But evidence suggests that a number of factors—such as the environment in the womb—can change a child’s long-term health prospects by determining which genes turn on and which stay silent.

The “On/Off Switch” for Genes

Along with our genes, we inherit certain "marks" that sit on our genes. Because these marks don’t alter the sequence of the gene, they are called “epigenetic.”

Epigenetic marks hold information such as which parent the gene came from. The marks also turn genes on or off. When working well, epigenetic marks help “bad” genes stay silent, while encouraging “good” genes to activate. When the marks improperly turn genes on or off, they may trigger later development of diseases such as diabetes , heart disease , and obesity .

But here’s the good news: unlike genes, scientists believe that epigenetic marks can be modified in the womb.

Research suggests that it might be as simple as common nutrients, such as vitamins, that change epigenetic marks in a developing fetus and affect which genes turn on and off. This research could eventually explain why some individuals who inherit genes for certain diseases may not develop those conditions as adults, while others do.

It could also provide a better understanding of how to prevent “bad” genes from activating later in life, and how to increase the chances of passing that protection on to future generations.

Pregnancy and Nutrition: An Epigenetic Link?

Scientists have long known that poor prenatal nutrition can influence the likelihood of diabetes, heart disease, obesity, breast cancer , and other cancers. Studies have shown that children born during periods of famine have higher rates of these chronic diseases when they become adults. Also, these children seem to pass on an inherited susceptibility to these diseases to their children.

Epigenetic marks could be the link. While the relationship between nutrition and epigenetics isn’t yet clear, early evidence points to the possibility that a pregnant woman’s diet can affect the epigenetic marks on her baby’s genes in a way that her children, grandchildren, and possibly great-grandchildren inherit the same health problems.

If a poor diet during pregnancy can damage the health of future generations through these factors, can this process be reversed to protect children? There aren't any human studies yet to address this. But an animal study offered some evidence. Researchers were able to stop the expression of cancer genes in mice by changing epigenetic factors—not the genes themselves, but whether they were turned on or off.

The study of autism and genes also lends support to the possibility that the environment in the womb can lead to certain outcomes for the child. Identical twins, who have the same DNA, are much more likely to share the diagnosis of autism than fraternal twins. But sometimes one identical twin is diagnosed with autism, while the other remains healthy. Experts have not yet identified the specific genetic components related to autism. But in a study, experts proposed that many factors—some of them related to whether genes turn on or off in the womb—are involved.

Best Bet for a Healthy Baby

What can a pregnant woman do to increase the chances of having a baby who expresses healthy genes? Research is still needed. Until we know more about the relationship between nutrition, epigenetic marks, and protection against diseases, pregnant women should follow their doctor's advice. Here are some basic guidelines:

  • Get good healthcare before, during, and after your pregnancy.
  • Eat adequately during pregnancy to avoid having an undernourished baby who fails to grow properly.
  • If you eat a mix of foods and enough servings from MyPyramid for Pregnancy and Breastfeeding , you will be eating a satisfactory diet. Another option is the Mediterranean Food Pyramid .
  • Folic acid is a key vitamin to the growth of your baby, especially during the first months of pregnancy. Take 0.4 milligrams of folic acid daily before and during pregnancy.
  • Avoid alcohol, tobacco , drugs, and other harmful substances while you’re pregnant.
  • Keep caffeine intake below two items per day.
  • If you’re pregnant and have diabetes , keep your blood sugar levels in control, stay healthy, and try to plan your pregnancy for a time when your diabetes is under control.