Obesity is an epidemic. It’s projected that by 2030, one in two adults and one in four children ages 5-9 in the United States will be obese.
Linda Barbour, MD, MSPH, professor of endocrinology and maternal-fetal medicine at the University of Colorado School of Medicine, believes interventions in pregnancy may help shift this trajectory.
“We know if a baby is born with excess fat mass at birth, it’s a risk factor of childhood obesity by the time they’re 9 years old,” she said.
Additionally, in large part, the number of fat cells a person develops is determined in the uterus and during the first six months of life. The Developmental Origins of Health and Disease theory also provides evidence of this important developmental time.
“From a metabolic perspective, organisms – including humans – are susceptible to programming very early. In primate studies, we know that feeding mothers a high-fat diet changes their baby’s appetite regulation, their muscular development, liver fat, and even their behavior.”
Barbour and her colleagues, Teri Hernandez, PhD, professor at the CU College of Nursing, and Jacob Friedman, PhD, have spent the last two decades trying to better understand babies born at high gestational weights.
For decades, screening pregnant mothers for gestational diabetes has been common due to the correlation of larger-weight babies born to women with high glucose levels associated with type 1 or type 2 diabetes and gestational diabetes. Yet Barbour says the majority of babies born large are not born to women with diabetes or gestational diabetes: they come from pregnancies affected by overweight or obesity.
Considering one-third of pregnancies are affected by obesity it’s a risk factor that is growing and a high-risk population cannot be ignored.
“Clearly, we have not solved the increasing number of babies born large for their gestational age or the childhood obesity epidemic by just focusing on glucose,” Barbour said.
In 2018, Barbour and her team published a study funded by the National Institutes of Health (NIH) that found that it wasn’t only a mother’s glucose levels that corresponded with the baby being born large.
Much more important than glucose, it was the mother’s level of triglycerides, a type of fat carried in the blood and associated with diets high in simple carbohydrates and saturated fats. High triglycerides can be deposited in adipose tissue, liver and muscle which causes excess fat stores, insulin resistance, and inflammation. Triglycerides are broken down by placental enzymes into free fatty acids. Free fatty acids can be used as building blocks for fat stores in a baby’s body, and sometimes can also be stored as fat in the baby’s liver. Excess fat stored in the liver may be a risk factor for the development of fatty liver in childhood, which is a growing cause of liver disease in children.
On average, triglyceride levels in women with obesity are 30-40% higher than women without obesity.
Shifting the focus from glucose to triglyceride levels, Barbour and her team have embarked on an NIH-funded community study of 80 pregnancies affected by overweight or obesity. Their goal is to understand how the elevated triglycerides both fasting and after eating affect the babies’ growth and fat stores.
The study is possible due to a handheld meter that allows the mother to test triglyceride levels at home. Similar to a glucose meter, the mother pricks her finger and applies blood to a test strip.
“We have the most wonderful moms in our community,” Barbour said, explaining how participating in this study is a big ask of a pregnant mom.
Study participants test themselves at four separate times during their pregnancy. They take four samples a day for four days (16 samples), recording fasting levels and levels after eating a meal. This will result in 64 total measures of triglyceride levels across the pregnancy, allowing the team to study the relationship between glucose, insulin, triglycerides free fatty acids and their relationship to fetal growth and the development of fat stores.
Their babies are measured soon after birth and at seven to 10 days of life, looking at levels of subcutaneous fat using a simple method called air displacement plethysmography (PEA POD). The team also uses an MRI to measure the baby’s liver fat levels, neither of which poses any radiation.
So far, the team has enrolled 24 women in the study and anticipates having results in the next few years.
Outside of pregnancy, it’s been shown that triglyceride levels can be normalized by introducing omega-3 fatty acids – “healthy fatty acids” – known to support metabolic health. Barbour and her team are also working on a smaller study that introduces omega-3s in pregnant women who have high triglyceride levels at the start of their pregnancy.
“The women are taking two capsules twice a day for the entirety of pregnancy, and we’re randomizing them to an identical placebo with soybean oil.”
Through the study, the team expects to learn more about how an omega-3 fatty acid dietary supplement may affect triglyceride levels in pregnancy, and possibly prevent excess triglycerides from being stored in the baby as fat or in the liver.
Barbour hopes these studies give moms the information they need to achieve better health for themselves and their children.
“I’ve worked with women for 35 years, and there's no more motivated group of people in the world, in my estimation, as pregnant women. They want to do everything they can for their baby.”
She wants to help women take advantage of the “life-changing” nature of pregnancy.
“If you can give moms some tools for their health, it's not just going to impact them personally. It's going to impact their children's health, and their entire family’s health, for the long term.”
Knowing the impact early development has on adult health, Barbour is hopeful that preventive measures can change the trajectory of the obesity epidemic.
“Once someone develops obesity, often by their teenage years, it is so hard to turn back,” she said. “At this point, their bodies are metabolically programmed to hang on to every calorie. Understanding this is important because prevention is a whole lot easier than trying to fix it down the road.”
Barbour’s team is currently recruiting pregnant women for the triglyceride studies called BASSINET and TOTS. Learn more at infantgoldresearch.org.
Guest contributor: Carie Behounek is a freelance writer who specializes in science and healthcare.