Epigenetics: What we inherit before we are born

Gene expression makes us who we are and it varies depending on how we live. We interact and are in a constant conversation with our environment. Our feelings, how lonely or happy we feel, go deeper than our skin, they control our cells. So when do these cells start learning? The nine months we spend in the womb are crucial. We learn about the world around us without being in it yet. These heritable changes in gene expression, that do not involve changes in the underlying DNA sequence, are otherwise known as epigenetics.

I design, therefore I become.

What does a baby learn in the womb?

A baby can start hearing their mother’s voice at the fourth month of gestation. The sounds of the outside world travel through the mother’s abdominal tissues and the amniotic fluid surrounding the fetus. The fetus is constantly hearing their mother’s voice and once they are born, they quickly recognize it.

Babies prefer this voice over anyone else’s, they become so used to hearing their mother’s voice that it can even be said they are born crying in their mother’s native language. A study was conducted where they found that French babies were born crying on a rising note, while German babies ended on a falling note, much like the patterns of those languages. Babies are born imitating the melodic contours of their future language. This learning has a purpose: babies prefer their mother’s voice because that person will protect them and they cry like their mother to create a stronger bond with her. Not to mention, gaining a head start on language development.

Babies also develop taste and smell by the seventh month of gestation. The flavors and spices of the food their mom eats travel to the amniotic fluid, which is constantly being swallowed by the baby. Babies remember and prefer these familiar tastes. These babies are already getting a sense of the very particular culture they will soon be introduced to. They get a hint of their culture’s unique cuisine!

The epigenetics triggered by stress

Although all of this learning influences certain preferences, it goes beyond developing a preference for spicy food. Nine months of molding and shaping are very consequential. A baby learns just as much from a mother’s stress levels and emotions during pregnancy.

A powerful example of the adverse effects of high-stress levels during pregnancy was triggered by the second World War. The Dutch Hunger Winter lasted from November 1944 to spring 1945, during German control of the Netherlands. The German blockade resulted in a catastrophic event when German troops blockaded Western Holland, turning away shipments of food. The Dutch were limited to only 500 calories a day (a fourth of their normal intake) and were left struggling to survive.

This dreadful event created a scientific study population. Due to excellent health care infrastructure and record-keeping in the Netherlands, this well-defined group could be followed and studied for long-term effects. The birth weights of children who had been in the womb during this terrible period were largely affected. Decades after this Hunger Winter, researchers documented that individuals born right after this winter had higher rates of obesity, diabetes, and heart disease later in life compared to others. These individuals also faced higher blood pressure, poor cholesterol, and reduced glucose tolerance.

Why does poor nutrition in the womb lead to these results in the long run? The fetus aims to survive under harsh circumstances and is forced to adapt. In this case, their mothers were faced with food scarcity, so they had to divert nutrients to critical organs such as the brain and away from other organs such as the liver or heart. The fetus is thus able to survive short term but suffers effects in the long term. According to the epigenetics principle, the organs that were deprived of nutrients became vulnerable to diseases. Fetuses prepare themselves for any external danger —they take in cues from the environment and adjust their physiology accordingly. They anticipate developing a sense of deprivation or abundance, and adapt to facilitate survival.

Another occurrence happened on September 11th, 2001. Tens of thousands of people surrounded the World Trade Center in New York City when it was attacked. Among the people physically and psychologically damaged by the attack, were approximately 1,700 pregnant women.

Researchers examined a group of women who were pregnant during this event. A great number of these women developed PTSD (post-traumatic stress disorder) following the event and researchers discovered a biological marker of susceptibility to PTSD –an effect that was largely evident in babies whose mothers had experienced this horrific event in their third trimester. So, in effect, the mothers who developed PTSD had given the epigenetic susceptibility of suffering this condition to their fetuses who were still in the womb.

This stress syndrome occurs as a reaction to stress from harsh and largely damaging, unpredictable events. The person gains a heightened awareness of one’s surroundings, quickly responding to any potential danger that can harm them. In this case, the response would be adaptive, especially in dangerous environments. So these mothers warned their children of potential dangers, communicating “it’s a dangerous world and you must be careful”.

Promoting a healthy pregnancy

What an expecting woman encounters in her day by day, the air she breathes, the love she feels, the chemicals she is being exposed to, and the emotions she feels are shared with her baby. The fetus takes these maternal contributions, making them their own. So how can we promote well-being and health to the next generation? We must be aware that learning is essential –and it begins much earlier than previously thought. What does this mean? We can now analyze the tiny individual dots that create the larger image. We have begun to unravel the link between nature and nurture: how our environment can communicate with us and alter us, sometimes forever, through epigenetics. Our DNA is a script, not a template, and how we frame the events in our lives can change the physical expression of cellular biology, and this will give meaning to our lives and future generations. In other words, we have the power to compose biological unfoldings, something that’s very powerful.

What a woman encounters in her day by day, the air she breaths, the chemicals she is being exposed to and the emotions she lives are shared. The baby takes these maternal contributions, making them their own.