Most expecting mothers know: smoking, alcohol, and drugs are all forbidden in pregnancy. They know the ways that these substances can negatively impact the health and development of their fetus. However, is food the new cigarette? New research has been pouring in on the negative effects of obesity during pregnancy. Read on to learn what we know about the ways babies’ environments during gestation can influence their future risk of obesity and related diseases.
People simply weigh more now than they used to, children included. More than three times as many kids are obese today than in the 1970’s. We now know that food is addictive. When people with obesity see food, their brains react similarly to the brains of opioid addicts seeing their drug of choice. What has happened over the last five decades that we now struggle with food as an addictive substance? One theory gaining increasing support is that we may be programmed for obesity in the womb.
This sounds like scary stuff! Where did we get such a theory? It starts with a theory called “Developmental Programming.” The theory goes: something happens to you during a certain period of development that leads to long term side effects. For instance, that something could be exposure to a chemical. Depending on when you are exposed to it, the side effects could be drastically different. For instance, let’s say you are exposed to an environment with low folate. Let’s say that you are 25 years old. Not such a big deal. Now, let’s say that you are not even born yet and you are only 4 weeks old. Your brain and spinal cord are only just starting to develop, and they need folate to do it! In this case, you could be born with a birth defect called spina bifida which could affect your functioning for the rest of your life.
As you may imagine, a human’s time in the womb is the most critical period for life-changing developmental programming. Before birth, more than 90% of all cell divisions needed to form an adult occur. Stressors and environmental influences during gestation can affect what types of cells you have, how many of these different types of cells you have, and how your body expresses its genes. It could affect the structure of your organs and your metabolic set point. Dr. David Barker first noted that the in utero environment could affect a baby’s lifelong risk of diseases like heart disease. The theory that the in utero environment may affect adult health became known as the Barker Hypothesis. The first infants studied were those born with low birth weight, especially those with fast catch-up growth. These infants were more likely to have insulin resistance, diabetes, fatty liver, and metabolic syndrome as adults. New research has shown that exposure to maternal obesity during gestation has similar effects. Babies born to obese mothers are at higher risk of obesity and chronic disease in adulthood.
Perhaps the most amazing research is how exactly babies become programmed during gestation. I’m going to dive into some biochemistry, so skip this paragraph if biochem makes your head spin! The hypothalamus in the brain controls appetite. There are two types of neurons in the hypothalamus that control appetite: orexigenic neurons and anorexigenic neurons. Orexigenic neurons increase appetite; they tell your body when it’s hungry and needs to go eat more. Anorexigenic neurons decrease appetite; they tell you that you’re full when you’ve eaten enough. These two types of neurons are largely set before you are even born. How does your growing brain know how many of each of these neurons to make? It looks to the surrounding environment. An environment with not enough nutrition tells your body to make more orexigenic neurons (more hungry neurons). Interestingly, the opposite environment has the same effect. An environment with an excess of nutrition also tells your body to make more orexigenic neurons (more hungry neurons). Therefore, your body is programmed to be hungrier before you are even born.
The hypothalamus is not the only way your body may be pre-programmed before birth to want to eat more or store more fat. Other ways this could happen are:
- Down-regulation of the brain’s reward pathway. It takes more food, especially sweets and high calorie foods, before the brain feels rewarded.
- More fat cell creation. Exposure to “Endocrine Disrupting Chemicals” in the environment could be contributing to making more fat cells, all of which want to be filled with stored fat.
- Propensity to store energy as fat.
- Resistance to insulin, predisposing to diabetes.
- Resistance to leptin, which tells the body when it’s full.
What are the best steps expecting mothers can take to minimize these risks to their unborn children? The first recommendation is to lose weight before pregnancy. Obviously this is not easy. It’s likely that many women are struggling against the programming their brains went through when they were babies. Hopefully, the knowledge of the benefits of weight loss before pregnancy can help shift the odds. Second, women who are pregnant can avoid excess weight gain. Once born, mothers should work with their pediatricians to help their infants grow at a healthy pace. Healthy growth, and not over-growth, of low and high birthweight infants is critical in minimizing their future risks. Breastfeeding is also protective. For mothers who choose not to or cannot breastfeed, optimal bottle-feeding is important. For instance, learning ways to comfort the infant without overfeeding is crucial. Finally, as I discussed in a previous blog post, we can minimize exposure to those disastrous Endocrine Disrupting Chemicals like BPA. For a baby, glass bottles are one way to minimize exposure. Hopefully this blog has inspired you to think of creative ways to optimize the in utero environment for babies!