Three Amazing Discoveries in Pregnancy Research

Germs, genes, and grey matter matters!
pregnant woman sitting in grassy meadow
Copyright CC0 Public Domain

It’s an exciting time to be having a baby, even if you, yourself, are not producing one. I discovered this as I was writing my book, Green Mama-to-Be: Creating a Happy, Healthy, and Toxin-Free Pregnancy (Dundurn, 2017). I had gone into it with a “let’s just get this over with” attitude. After all, I am done having babies (I hope), so what more did I really need to know about those months? Happily—I found out—lots!

I learned about three things that we can all benefit from knowing and sharing. These are ideas where the research is very new and the studies are only recently being published and they are changing the very idea of what we thought to be true about the nature of human life—within the belly and without. They are also fundamentally hopeful concepts: perhaps a healthy constitution—or lack thereof—is not as set in stone as we once believed.

The womb is more fruitful than you thought!

Not just a haven for humans, it is also a harbour for other small organisms. Until very recently, scientists and doctors believed that the uterus was a sterile environment and a child’s first exposure to bacteria was during the passage through the birth canal and right after. The baby’s microbiome— an ecological community of microorganisms that share our body space—is dramatically affected by what happens during and immediately after delivery. To begin to understand the importance of this, it’s essential to appreciate that humans are composed of trillions of bacteria. We are made of as much bacteria and other microbes as we are our own human cells. At least some of this bacterial life—such as what lines our gastrointestinal (GI) tracts—has coevolved uniquely with us and is essential to human health, most especially the functioning of our immune system. In other words, to be in a state of complete health, the full complement of a harmonious microbiome will include all the human cells as well as organisms that might be classified as viruses, parasites, and other as-yet-unidentified microbes. A healthy human gut will be different from that of a healthy rat gut, and the microbiome of one healthy human’s gut might be quite different from that of another healthy human. We have similarly unique microbiomes in our mouths, vaginal tracts, and on our skin, and, interestingly, the microbial composition of the uterus is said to resemble that of the oral cavity more than the vaginal canal, despite their proximity.

Factors such as having a vaginal birth, skin-to-skin contact, and breastfeeding are all extremely important in seeding the baby’s microbiome. In fact, some researchers can tell the difference years later between the microbiome of babies born vaginally and those born by c-section. Some birth providers are starting to use this science in hospitals by swabbing babies born by c-section with the mother’s vaginal secretions to help mimic the superior bacterial exposure of a vaginal birth. There is research to indicate that the baby’s microbiome will also be affected by his weight at birth as well as the mother’s weight, dental health, and her own antibiotic use during pregnancy, and that aspects of the mother’s microbiome can be passed down to the child and then on to the grandchild and great-grandchild and so on through each birth process. As we shall see later, even genetics are not immune to the influence of the mighty microbiome!

The microbiome diaspora

The big news is that in the last few years, scientists have established that there are also bacteria in the amniotic fluid, placenta, meconium, and the fetus’ intestines, and that the microbiome that begins to develop in the womb is also influenced by the mother’s health and diet. It is suspected that some pregnancy complications, such as pre-eclampsia, could be the result of infections that develop from an unbalanced or deficient microbiota and that consuming probiotics may inhibit pathogens and reduce inflammation associated with preterm birth.

We also know that the gut microbiome has been changing over the generations: namely, becoming less diverse. This is assumed to be a bad thing, much like how a lack of diversity and invasive species cause problems in nature. The likely culprits include our modern diet—which is higher in fats and simple carbohydrates and lower in fibre than traditional diets—and our current practice of using household antibacterial products, as well as an overuse of antibiotics. Infertility treatment has often introduced antibiotics into the uterus in an effort to improve the chances of implantation, however, a 2012 review found no correlation between successful implantation and such treatment. In short, we must have bacteria and other microbes—and lots of them!— for human life to exist and we need them in good balance to be healthy.

Although there is still a lot we don’t understand about our microbiome and its role over generations, what is clear is that a mother can help ensure the best future microbiome even before she conceives and onward through the child’s life by focusing on eating a whole-foods-based diet with lots of good fats, vegetables and other nutrient-dense foods. A diet is further enhanced through adding probiotic-rich foods and drinks such as sauerkraut, beet kvass, kimchi and kefir. It also means avoiding antibiotics unless medically necessary and forgoing antibacterial products such as Triclosan (found in most hand soaps, many cleaning products and even toothpaste). Chlorine and fluoride in water can also have an antibacterial effect, so filtering your tap water is a great way to continue to get the benefits of water without harming the microbiome.  

Epigenetics: uniting the two solitudes of nature and nurture

Most people are aware of the basic nature versus nurture question: How much of “us” is determined by genetics and how much by environment? And for many, many years, most of us—including scientists—thought they were in two distinct categories: both important but very different.

Enter the world of epigenetics, the study of environmental factors that turn genes “on” or “off”, determining whether and how genes are expressed. Epigenetic changes don’t affect a person’s fundamental DNA, but are, to some extent, altered by our present choices. Research shows that the influence of the womb can begin as early as conception and it is thought that what happens there, particularly in relationship to nutrition, stress and environmental contaminants such as smoking, can impact the expression of the growing child’s genetics.

It doesn’t stop, or start, there. The changes in those genes can be passed on through the generations. The Overkalix study, a Swedish study of transgenerational epigenetic inheritance published in 2002, looked at the members of an isolated community in Sweden born between 1890 and 1920. It showed how poor food supply could influence mortality, obesity, and diabetes in grandchildren.

Reproducing like cats

One of the early research pioneers in nutrition’s generational effects was Dr. Francis Pottenger. From the stories I’ve read, Pottenger sounds like one of those really smart, eccentric men who didn’t let much stand between him and “just figuring it out.” In the 1930s, Pottenger studied the health of 900 cats over four generations. He fed one group cooked meat or pasteurized dairy, typical of the ingredients in dried cat food. He fed the other group a diet closer to what they might find in nature including raw organs and meats, and raw milk. Then he examined the health, weight, calcium and phosphorus levels, skeletal structures and dispositions of the cats for ten years. Within three months, the first group started experiencing dental degeneration. Things got worse from there: miscarriages, higher infant and maternal mortality, a dramatic increase in skin diseases and allergies, bone deterioration, hypothyroidism and personality changes. This group died out completely by the fourth generation. Meanwhile, the second group, which ate the raw diet thrived generation after generation. Pottenger then tried to restore cats of the first group back to optimal health with diets of raw milk and meat. In restoring the health of the second generation (since the original third generation died before they could reproduce), he found that the next third-generation offspring generally, though not completely, showed improved health which in turn was passed on to the following generation. Pottenger’s observations were an early experiment in epigenetics: each new generation was not a clean slate, but seemed to inherit the physical degeneration caused by the nutritionally inadequate diets of the generations before. Much research is being done in the field of reversing epigenetic changes as this new understanding emerges.

Babies born to mothers who smoke have long shown impairment in such things as lung function and other birth defects and are more likely to suffer from asthma and later substance abuse. These children tend to show epigenetic changes not present in the DNA of non-smokers’ children, exhibiting an altered DNA methylation profile. DNA methylation is an epigenetic mechanism that impacts the gene expression vital to healthy growth and development, and research is starting to suggest that prenatal folate and B-vitamin intake has good potential to contribute to this mechanism.

Repairing the damage of predecessors

While epigenetics sheds light on possible problems, it also gives us hope. Which generation of Pottenger’s cats are you? Almost certainly we aren’t the lucky recipients of four generations of great, wholesome eating. I grew up poor and spent my early childhood eating processed food from a box supplied by the government. My mother fared a bit better because she grew up middle class and at a time when there were far fewer contaminants in our air, water, and food. My grandmother’s family had the closest to an optimal diet, raising most of what they ate themselves and with ready access to fresh eggs, real milk, and almost nothing processed. So, I am the “revival generation”, working towards restoring better health for me and my children, and consciously aiming towards optimal health for my children’s potential descendants.

The incredible expanding/shrinking brain!

That mushy feeling and all the underlying emotions that seem to go along with pregnancy are real and they serve a good purpose. Mothers’ brains both gain and lose grey matter and undergo rewiring. It’s as if the brain is indeed being turned to mush with the help of all those pregnancy and postpartum hormones—including oxytocin, estrogen, and prolactin—so that it can be reconstructed for the work of being a mother. Indeed, many of those so-called pregnancy and postpartum emotions, including love, protectiveness, and even worry, begin in the brain. Like so many other aspects of human biology and pregnancy, scientific understanding of what happens to the brain in pregnancy is undergoing massive breakthroughs and science is beginning to catch up to what mothers already know: the brain changes aren’t just “in our heads”.

The struggle is real…the baby did eat your brain

In December of 2016 a new study came out and the headlines all read some version of: “Pregnancy shrinks brains!” I found this particularly interesting because a few years before, studies had come out and the headlines all screamed, “Pregnant moms grow new brain!” What gives, I wondered?

Both studies showed that first-time mothers consistently demonstrated a notable difference in grey matter volume, but in different parts of their brain. Mystery solved! The older study showed an increase in grey matter in areas including the prefrontal cortex, amygdala, and the hypothalamus—all connected to emotional regulation, survival instincts, and hormone production, and associated with a well-adjusted new mom. Conversely, if these areas shrank, it correlated with more stress, anxiety, and poorer experiences of mothering. The newer study showed that moms with the best mother-to-child attachments (such as feelings of empathy and pleasure toward the child) had a decrease in the medial frontal and posterior cortex lines involved in social cognition—how we process, store and apply information about other people and social situations. The researchers surmise that this period is one of great synaptic pruning, similar to what happens in a young child and again in adolescents, where underutilized neurological pathways—synapses—are eliminated to make way for new neural networks. The researchers found no corresponding changes in memory or other cognitive functions.

Of particular interest to many researchers is what happens in the amygdala, a part that the older study above said ought to grow and which helps process memory and govern emotional reactions such as aggression, anxiety, and fear. In most mothers’ brains, this area continues to increase in the weeks and months after giving birth and is full of receptors for that cocktail of hormones that help feed the love, attachment, and care between mom and babe. It’s the part of the brain that lights up when the mother stares at her baby or elicits one of those early smiles. If that part of the brain is damaged or not growing normally, the results in the mother are noticeable and linked to higher levels of depression and greater anxiety. In the child, a damaged amygdala may affect whether he can distinguish between his mother and anybody else. This part of the brain is also particularly sensitive to oxytocin— the love hormone responsible for maternal-infant bonding. Oxytocin dramatically increases in pregnancy, the postpartum period, and with breastfeeding. The more the mother is involved with her child, the greater the increase in oxytocin.

The changes in a mother’s brain are most dramatic with her first child, and it isn’t clear whether all the changes ever fully return to their pre-pregnancy state, but there is evidence of the decreased-volume effects lasting at least two years. Some researchers explain that it is as if all women have the blueprint inside their brains for motherhood. It’s not all about the mothers, however! Despite never experiencing pregnancy, research shows that even dads have the capacity for brain changes driven not by oxytocin, but directly tied with caregiving. The more involved the father, the more he is supported by a feedback loop that helps wire his brain for that involvement.

It's an exciting time to be parenting, pregnant or just interested in the human body. A bit of understanding about the diversity of microbes, the powerful role of epigenetics, and our amazing, changing brains demonstrates that our health and the health of future generations can be positively and profoundly influenced in many ways. These are just three of the hundreds of discoveries which, while exciting, are still curiously new—who hasn’t wondered about the mysterious and miraculous goings-on that pregnancy effects? The science of the pregnant body and brain is, well, still in its infancy, but growing dramatically with promises to pursue and beget more discoveries in the field of pregnancy research earnestly pledged in the conclusions of each study. Whether you’re a parent-to-be or any other type of amazing human, such knowledge can benefit anyone seeking insight into human health—reproductive or otherwise.