Updated: Jan 15
History of maternal nutrition
In the early to mid 20th century, pregnant women frequently drank alcohol, smoked cigarettes, and were mostly unaware of a growing fetus' nutritional needs. The fetus was believed to be immune to both environmental toxins and toxic substances consumed by the mother. The importance of maternal nutrition only became obvious when people began to see the relationship between substances the mother ingested and tragic birth defects.
Throughout history, we've seen the connection between a mother's health and the health of her child and today we understand the direct impact that food, alcohol, medication and supplements have on a growing fetus. One of the earliest examples of this comes from a common morning sickness medication, thalidomide, taken by pregnant women in the 1960's. As a results, over 10,000 children were born with brain damage and missing limbs (1).
In 1971, a synthetic estrogen drug known as diethylstilbestrol was linked to the development of an extremely rare vaginal cancer in young girls, a disease that previously only effected menopausal women. (2) This is one of the findings that shows how events occurring during gestation (pregnancy) are capable of impacting the future health of a child.
One of the most well-known fetal risks is fetal alcohol syndrome, caused by the consumption of alcohol (usually large amounts) during pregnancy. It wasn't until 1973 that fetal alcohol syndrome was first formally diagnosed, and not until 1989 that the United States government began requiring warning labels directed at pregnant women to be in place on all alcoholic beverages for sale. (3)
What is the Barker Theory?
The Barker Theory, also known as the fetal origins hypothesis or the fetal origins of adult disease hypothesis, suggests that adverse nutritional factors during critical periods of fetal growth and development increase the risk of disease in adulthood. The idea behind this hypothesis is that we are "hardwired for life." It is sometimes hard for people to accept this idea because millions of people around the globe suffer from malnutrition either because they cannot afford vitamins and nutrient dense foods or they live in famine-stricken countries. Even if we were to accept the Barker Theory, there is only so much we can do to improve maternal nutrition for mothers everywhere.
The Barker Theory not only looks at the effects of undernutrition on a fetus, but also the effects of overnutrition, diabetes, stress, obesity, influenza, diet, and pollution on a developing fetus. Studies show that fetuses and infants of mothers with diabetes have a higher risk of stillbirth, congenital heart defects, hyperbilirubinemia, and immature lungs. (4) Other studies show that children of women who were obese during pregnancy have a much higher chance of developing heart disease, obesity, and diabetes later in life. (5)
How exactly is nutrition effecting the fetus?
The growing fetus is very smart and will adapt in order to increase its chances of survival in extrauterine life. This is known as the predictive adaptive response and is a way that species evolve overtime to adapt to their changing environment. One way the fetus does this is by suppressing or activating certain genes depending on the mothers nutrition intake. Glucose intake is a great example of this.
If the mother is not getting an adequate intake of glucose, the fetus will think that there will not be a lot of glucose once it gets into the real world. If there will not be a lot of glucose, then the fetus doesn't need to produce as many insulin receptors and it will suppress the gene that produces these receptors. The problem is that once the fetus enters the world, it is not prepared for the amount of glucose there actually is — the majority of our diet comes from glucose.
Once the glucose gets into the blood stream, there are not enough receptors to take in all of the glucose into the cells. This decrease in the uptake of glucose causes insulin resistance and an increase in circulating glucose and free insulin, which eventually can lead to type two diabetes.
We saw this trend of decreased maternal glucose intake and glucose intolerance in the offspring of mothers who were pregnant during the 1944-1945 Dutch famine (6). The same results were shown when studying offspring of pregnant mothers during the Siege of Leningrad (now St. Petersburg) from 1941-1944.
Why is the Barker Theory Important?
Organogenesis (the development of organs) begins just three days after fertilization. This is often before a woman even knows she is pregnant. Also, 50% of pregnancies in the United States are unplanned, as women were not been preparing their bodies for pregnancy (7). There are different critical periods of growth and development for each organ and body system and it is crucial that the mother has sufficient vitamin stores and nutrients to support her growing baby's needs. We have a pretty good idea of when these critical periods are and we know which nutrients are critical for proper development of each organ and system.
For example, we know that folic acid deficiency is linked with neural tube defects, iodine prevents brain damage, and iron deficiency increases risk for a premature birth. Pretty much every nutrient has a purpose in the body and if a mother has a deficiency or doesn't have her nutritional needs met, how can the fetus get what it needs to grow?
All in all, the Barker Theory is important because what the mother eats, drinks, and ingests directly impacts her growing fetus. There is always a balance with what the growing fetus needs and what the mother can provide which is why the fetus will adapt its genes to increase its chances of survival in extrauterine life. If the mother is malnourished during pregnancy, this could potentially have a negative impact her baby and possibly impact the child for the rest of its life.
Are we really "hardwired" for life?
I believe that maternal nutrition plays a critical role in fetal development. Though the Barker Theory is just a theory, when we look at the studies, we see a clear connection between nutrient deficiencies and negative fetal outcomes. It's these studies that lay the grounds for current prenatal recommendations for vitamins such as folate, vitamin B12, iron, magnesium, vitamin C, calcium, choline, and iodine.
However, just because nutrition is critical for the fetus does not mean it's not important in all other stages of life. Children and adolescents have high nutritional needs because they are still growing and developing. In adulthood we need to be conscious of nutrition to maintain our organ functions, prevent diseases, and for reproduction. Even as older adults, nutrition is important to maintain muscle mass and keep our brains healthy. Nutritional needs are always changing, but they are very important in all stages of life.
Just because we were exposed to a risk factor in the womb does not mean we will definitely develop a certain disease. Iron deficiency does not automatically cause a premature birth and not taking an iodine supplement will not cause a child to be born with neurological problems. But we can see correlations in studies and we know that women need to be especially conscious of their nutritional intake during pregnancy because what they eat and are exposed to directly effects their growing baby.