How our waistlines are defined before birth

A mother's diet can greatly affect her child's weightHow a woman’s diet affects her unborn child has been the focus of studies for decades. Doctors, registered nurses and medical assistants have long counseled pregnant patients on the proper diet to keep the baby healthy. But for the first time research into this integral element of childhood development has found that obesity and poor health in children may be caused by the mother’s diet before the child was born.1

Studies find that high-fat diets lead to overweight offspring

A study was conducted and the findings were published in the January 2014 edition of the journal Cell. The goal of this study was to explore how mothers’ diets affect their children’s waistline, and how genes play a role in body mass, fat percentage, and metabolism. The researchers that conducted this study worked with mice. They fed pregnant mice a high-fat diet at different stages in their pregnancy to determine when the most critical period of fetal development was. The researchers found that mother mice that were given a diet high in fat while they were nursing their young had drastically heavier male offspring with a higher body fat percentage than mother mice fed a normal diet during this time. The male young also had more of a resistance to insulin along with glucose intolerance, which are two precursors for type-2 diabetes, even if the offspring themselves consumed a normal diet. The researchers also found that the poor health effects were only seen in the female babies if they ate a high-fat diet, but not if the babies later ate normally.1

The researchers investigated the relationship between the high-fat diet and the instances of weight gain by studying the hypothalamus, which is a hormonal center in the brain that works to regulate metabolism. The hypothalamus releases a chemical called aGRP/Neuropeptide Y when an individual is hungry. When the individual is satiated or full, the brain releases the chemical POMC.1 The difference between the brain of a baby mouse and that of a human is that in baby mice, neurons continue to develop after they’re born. In humans, however, neural development is more established at birth. This means that the nursing stage in mice actually corresponds to the third trimester of pregnancy in humans. Thus, the researchers concluded that the most important time for human fetal development is during the last trimester.1

Researchers believe that the decreased density of the brain cell fibers in the baby mice who had mothers who were fed a fatty diet is what has an effect on the processing of insulin and glucose. Those effects lead to the glucose intolerance and higher levels of insulin in the babies. The study also found that the part in the brain that is involved in suppressing appetite and stimulating metabolism was also dramatically affected. Baby mice who had mothers on the high-fat diet did not release a hormone called TRH, which stimulates the thyroid. This hormone is involved in weight regulation, so when the baby mice did not release this hormone, they tended to weigh more.1

Mothers can affect their child’s future health with diet and exercise

While the researchers believe these findings help to explain the obesity epidemic that seems to be plaguing America’s children today, the majority of the health problems seen in the baby mice were only triggered after they themselves were fed a diet high in fat. When the offspring were fed a normal diet, they did not display as much evidence of elevated body fat or insulin resistance.1

Other studies have also concluded that changes in diet can alter the function of genes, a phenomenon called epigenetic change. Researchers have studied samples from the umbilical cord and looked for “epigenetic markers,” which showed that mothers who consumed early pregnancy diets that were low in carbohydrates, like sugars and starch, had children with these epigenetic markers. A strong connection was found between those markers and a child’s weight gain at ages 6 and 9. Whether the mother was obese or not, if she consumed a diet low in carbohydrates, her children would remain at a healthier weight as they aged.2

However, more doctors and medical assistants are also encouraging physical activity for pregnant mothers, and studies emphasize how exercise is another major component of keeping babies at a healthy weight. It’s been shown that women who maintain a moderate exercise routine throughout their pregnancy deliver babies that are at a normal weight, and their children continued to stay healthy over the next three to six years. This information suggests that exercise greatly reduces the amount of extra fat laid down by the babies. Research has also shown that exercise does not seem to interfere with the natural changes in the mother’s response to insulin, which is a necessary mechanism in pregnancy to make sure the fetus is properly nourished.3

The findings from all these studies emphasize the fact that doctors, medical assistants and nurses should make counseling pregnant patients on proper nutrition and fitness a top priority. Women should be aware that their baby’s future health can be affected if the mothers consume a healthy, well-balanced diet that is low in saturated fats and rich in fresh fruits and vegetables. Doctors can also recommend that their female patients take vitamin and mineral supplements called prenatal formulas starting several months before conception to ensure that their nutritional status is healthy and stable and ready to support fetal development.4

1 Smith, Dana, “How a Pregnant Mother’s Diet Could Change a Child’s Brain,” The, Feb. 18, 2014,

2 Gallagher, James, “Mother’s diet during pregnancy alters baby’s DNA”, April 18, 2011,

3 “Pregnancy exercise ‘slims babies’,” BBC, April 5, 2010,

4 Marie, Joanne, “How Does a Poor Diet Affect Fetal Development?” Live,

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