Though most people tend to think of obesity as the product of sloth and gluttony, most of us accept as “biological” the fact that fatter parents tend to have fatter children.
But the link goes deeper than that.
Children can inherit tendencies towards weight gain in the same way that they may have their mother’s nose or father’s chin. Body fatness, response to overfeeding, how efficiently we burn calories, and even our food choices are all very much inherited and all potentially influenced by what happens to us in the roughly nine months before birth.
This connection — between life in the womb and the likelihood that its inhabitant will be obese — is being largely left out of the national conversation about obesity prevention and weight loss. In fact, there is a substantial body of evidence suggesting that closer attention to maternal nutrition, exercise, stress and medications during pregnancy may help reduce the fatness of Generation Z, especially those already at risk of obesity by virtue of their family history.
Obesity is a national problem. Approximately two-thirds of adults and one-third of children in the United States are overweight or obese, and 80 percent of adults and children who try to lose weight and keep it off fail. Obesity prevention programs such as Michelle Obama’s “Let’s Move” campaign seem to be a logical, cost-effective way to decrease the fatness and improve the health of our children, regardless of whether or not they are obese.
Yet while these programs have helped to make obesity prevention a topic of public discussion, they have not been as effective as expected. Over the past decade, the percent of obese adults nationwide has increased by almost 20 percent, and the percent of obese children has not changed, despite new public service announcements, medications, diet books and soda taxes.
Studies of “epigenetics” — changes in the environment that increase or decrease the impact of genes without actually altering them — suggest a less expensive, and probably more effective way to improve the health of the next generation via a nine-month plan that would complement any subsequent efforts at home and in school.
The NIH and major academic centers recognize the enormous potential of epigenetic therapies to “quiet” genes associated with cancer, obesity, and other diseases and “turn on” genes that protect against these modern scourges. However, prenatal care designed to reduce the risk of subsequent disease in offspring is underrepresented in most medical practices — probably because most of us stop reading and turn the page when we see the word “epigenetics.”
Many aspects of the prenatal environment impact whether the child will be obese, including the weight of the mother and her weight gain during pregnancy. Children of mothers who had bariatric surgery are thinner, and have lower blood pressure and insulin than their siblings who were born before their mother lost weight.
Nearly half of the pregnant women in America gain too much weight and about 20 percent gain too little during pregnancy. Not surprisingly, as the rate of pregnancy weight gain increases, so does the risk of future obesity, especially for children of obese mothers: overnourished, “large for gestational age” newborns are more likely to become obese adults.
Surprisingly, undernourished or “small for gestational age” babies are not only more likely to become obese, but also more susceptible to type 2 diabetes, high blood pressure, and other complications of obesity. These babies are “at-risk” of these complications at lower levels of body fatness than someone who was born within the expected weight range.
This information is extremely relevant to pediatricians and internists, who should be screening their patients with a history of low birthweight for diabetes and cholesterol problems earlier and at lower weights, and working harder to prevent even small, but unnecessary weight gains.
It even matters when in pregnancy the undernutrition occurred. From 1944 to 1945, the Dutch population was forced to live under a Nazi-imposed blockade on all incoming trade, including food. As a result, the average person was rationed to fewer than 1,000 calories per day in what has become known as “the Winter Hunger.” Fetal undernutrition in the first or second trimester of pregnancy resulted in a significantly higher incidence of obesity age at age 19 in both men and women, as well as significantly worse cholesterol, sensitivity to insulin, and overall health. Even at age 50, women who had been exposed to the famine in utero during the first trimester were about 7.5 percent fatter than those from areas outside of the embargo.
Weight gain during pregnancy and prenatal nutrition are only the tip of the iceberg of things that could be controlled to affect the risk for obesity. Maternal smoking, antibiotic use, and emotional, medical, or psychiatric stress all increase the risk of childhood obesity as well as diabetes, high blood pressure, and high cholesterol.
I’m not suggesting that pregnant women should be relegated to a sterile, spa-like environment. But together with their ob/gyns, they should recognize the womb as a tool to promote a lifetime of better health for their children. The metabolic groundwork of adult degenerative diseases is laid down in childhood, and awareness of the risk of these problems as reflected in family and pre-natal history will facilitate further risk-reduction in the pediatrician’s office.
Excessive weight is the most common chronic disease in the world. In the United States, healthcare costs associated with obesity top $200 billion annually (20 percent of our national health bill), plus billions more due to worker absenteeism and money spent on interventions that don’t work. Even a small dent in this problem would result in substantial health benefits and cost savings.
Better prenatal care by applying the lessons of epigenetics will not solve the problem of obesity or its complications. But it will reduce the risk of obesity — and augment efforts to promote a healthier lifestyle in schools and homes
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