Exercise During Pregnancy Benefits Your Child’s Health Through Epigenetics

Americans need exercise, badly! In the United States, 42.5% percent of adults are obese. Another 31% percent of American adults are overweight. We need exercise, not simply for the obvious physical benefits but for the beneficial psychological aspects as well. In fact, regular exercise is probably the most helpful and simplest intervention to help reduce the widespread occurrence of several chronic diseases. 

Pregnancy is no exception to the need for exercise. There is an ever growing body of medical evidence that confirms that exercise during pregnancy is not only beneficial for the expecting mother, but has beneficial effects for the unborn child through a process called epigenetics. 

Understanding Epigenetics

Epigenetics refers to how our behaviour and environment can affect the way our genes work. We now know that one’s health outcomes (and even certain psychological conditions) are largely determined not just by physical DNA itself but by how genes are turned “on” or “off”. Historically, genetics was mainly focused on physical changes to our DNA strands themselves- the addition of parts of genetic material, or the removal of certain sections of DNA, or the altering of some small points along the DNA strands. These genetic mutations, deletions, or duplications have to do with the physical DNA strand structure, and yes- they are definitely linked to some disease states. But what the scientific and medical community has come to appreciate is that having those gene alterations alone is not enough. Those genes must be either turned on or off to express themselves. The activities that we do (including behaviors like exercise, or lack thereof, and what we eat or drink) and even the environment we find ourselves in, all contribute to the expression of those genes. In other words, we are not just our genes, but we are the product of the epigenetic changes those genes go through to express themselves in our lives. For example, if someone carries the feared BRCA cancer gene, known for its increased rate of breast and ovarian cancer, it does NOT mean that person is doomed to develop those dreaded malignancies. The expression of that BRCA gene may be modified by epigenetics, and we have a large role to play in that capacity by taking care of our body through diet and exercise. We truly are all products of both nature (the actual DNA code transmitted to us) and nurture (the environment and behaviors we expose ourselves to). 

DNA methylation is one of the most applicable and well-studied epigenetic mechanisms known to affect gene activity. In this process, a “methyl” group (a chemical unit) is added to our physical DNA material. This process doesn’t affect our DNA sequence, but rather turns genes off. This can have positive or negative consequences for certain diseases depending on which genes get silenced. Here is an amazing medical fact: the poor health conditions of parents prior to and during pregnancy can have negative consequences to the developing child, likely through these methylation changes of their genes. Thankfully, these changes can be reversed.

The benefits of exercise during pregnancy

It is well accepted that the perinatal period is a crucial time for the programming of the offspring’s future, both with regards to good health as well as disease susceptibility. This is largely the result of epigenetic changes in the developing child while in the womb. Medical studies have shown that exercise during pregnancy not only benefits the expectant mother’s health, but also that of their offspring. For example, it has long been known that children born to obese parents have a higher risk of developing metabolic disorders like diabetes, kidney damage, and heart disease later in life. They are also more likely to become obese themselves. This susceptibility of the unborn child to the development of obesity and type 2 diabetes which can be traced back to an adverse intrauterine environment during early development is known as “metabolic programming.” Although we may not be able to alter the physical DNA passed down to us through the womb, we can still have control over our health. Obese mothers and/or fathers can be proactive and address health concerns to change outcomes for themselves as well as their future offspring.

One study showed that exercise during pregnancy can actually protect the growing baby from acquiring the harmful effects of parental obesity by offsetting abnormal DNA methylation in the offspring. The authors stated:

“The results provide the first evidence that maternal exercise only during pregnancy can prevent the transmission of metabolic diseases from parent to child.”

However, these are not the only researchers to confirm this link between maternal diet and exercise and their impact on the developing child’s DNA. Other researchers from the University of Southampton and King’s College London also found that diet and exercise interventions in the mother significantly reduced methylation changes in the infant associated with diabetes in the mothers. Exercise was shown to minimize or reverse some of the high‐fat diet associated methylation patterns which can affect the offspring’s DNA. 

The benefits of exercise during pregnancy are not limited to physical health conditions in the offspring. Exercise has also been shown to impact fetal neuro-cognitive development as well. Hippocampal DNA methylation has been shown to be lower in exercise-exposed offspring. This improves childhood learning and possibly even prevents mood disturbances in the offspring. Several recent studies indicate that the offspring of mothers that exercised during pregnancy exhibit improved learning and memory and decreased anxiety-like behaviors. These epigenetic (methylation) changes can actually be proven by lab tests of the child’s DNA. 

But wait, there’s more… The paternal contribution

Traditionally, the emphasis for a baby’s healthy development was focused on the mother’s health throughout her pregnancy. However, there have been a wide range of studies showing that the physical health and fitness of the father at the moment of conception can greatly impact the physical health of his offspring. Obese dads can pass on predisposition to obesity and metabolic disorders to their kids. These studies suggest that paternal diet and physical activity levels may induce changes to the molecular makeup of sperm, which in turn, programs embryos and lowers their risk of metabolic and reproductive health problems.  

There is also scientific evidence that the father’s physical and emotional state can impact his sperm quality, and therefore his offspring‘s future health through these epigenetics changes. The same is true for mother’s stress states and conception. Many other studies have now shown that if a mother is stressed, anxious or depressed while pregnant, her child is at increased risk for having a range of problems, including emotional problems, ADHD, conduct disorder and impaired cognitive development. That means that anxiety and emotional stress may not simply be a learned response but may be traced back to the womb. 

What kinds of exercises are safe during pregnancy?

Yes, exercise is allowed while expecting! In pregnancy, physical inactivity and excessive weight gain have been recognized as independent risk factors for maternal obesity and related pregnancy complications, including gestational diabetes mellitus and high blood pressure. In 1985, the American College of Obstetricians and Gynecologists (ACOG) issued the first guidelines for prenatal physical activity. These were based on the expert opinion of a panel of obstetricians. They endorsed the safety of most aerobic exercise but advised caution with high impact activities such as running, and included restrictions for duration (no longer than 15 minutes for strenuous physical activity), heart rate (no greater than 140 beats/minute), and core body temperature (no greater than 100.4°F/38°C). But medical data moves fast. The ACOG provided its most recent guidance regarding exercise during pregnancy in March 2020. The ACOG states:

“… studies of women who exercise during pregnancy have shown benefits such as decreased gestational diabetes mellitus, decreased cesarean birth, and decreased postpartum recovery time. Physical activity also can be an essential factor in the prevention of depressive disorders of women in the postpartum period.” 

The guidelines also state that the pregnant patient should work with their healthcare provider to establish an exercise program that leads to an eventual goal of moderate-intensity exercise for at least 20–30 minutes per day on most or all days of the week. This can be adjusted as medically indicated. Pregnant women who were more sedentary before pregnancy should follow a more gradual progression of exercise while expecting.

So, what’s the take home message? 

We have a huge opportunity to impact our future children’s emotional and physical future wellness not only by the physical genetic material that we pass on to them, but by our behaviors as well. The cycle of metabolic risk transmission could be greatly reduced if mothers knew they could improve their children’s health by exercising before and during pregnancy. However, this responsibility is not limited to the expecting mom. It is something equally shared by the father as well. By establishing healthy eating habits, regular physical exercise, and improving our emotional well-being before and during a pregnancy, we can help better shape the future of our children.