UCLA. US: Veronica Romero was 21 years old and worried. Pregnant with her first
child, she was putting on a lot of weight. Her obstetrician leveled with
her: “You’re gaining too much.” But as she approached 50 pounds of
weight gain near the end of her pregnancy, Romero felt helpless.
“I tried to watch what I was eating, but it was so hard. Pregnant
women get cravings, and my cravings were sugary,” she recalled.
“I tried to eat carrots and small appetizers, but it didn’t work. I
was disappointed. I didn’t want to get bigger.” The pregnancy set into
motion a health crisis on two fronts: for Romero, now 38, and her son,
Anthony, now 17. Romero eventually grew to nearly 300 pounds, and
Anthony became a big baby, then a chubby toddler and now an obese
adolescent.
This mother-child pair is not unique. The obesity tsunami that has
washed across the United States over the past four decades has swept up
pregnant women and their offspring too. In fact, pregnant women today
are considered by some medical authorities to be at the nexus of the
obesity crisis. Abundant research has revealed that pregnancy is a key
period of increased risk for developing obesity in women and that
obesity in pregnancy may genetically “program” offspring to become
overweight or obese later in life.
The concept, commonly known as fetal programming, is rapidly altering
the fields of obstetrics and pediatrics, said Dr. Sherin Devaskar,
Mattel Executive Endowed Chair of the Department of Pediatrics,
physician-in-chief of Mattel Children’s Hospital UCLA and assistant vice
chancellor of children’s health. “There have been many studies to prove
beyond a doubt that fetal programming is real. If a mother is obese,
her babies are at very high risk for obesity and chronic disease.”
In the United States, more than half of all pregnant women are
overweight or obese, according to the American College of Obstetricians
and Gynecologists. An estimated 9 percent of babies are born
macrosomic — weighing too much for their gestational age. Fetal
macrosomia is typically defined as a birth weight of more than 9 pounds,
15 ounces, regardless of gestational age.
However, obesity in pregnancy can also result in babies who are born
prematurely or underweight. These infants also seem to be predisposed to
obesity and related diseases, such as diabetes and heart disease, later
in life, Devaskar explained.
More than three decades ago, Dr. David Barker, a British physician
and epidemiologist, linked birth weight, either excessively high or low,
to a heightened risk of heart disease, type 2 diabetes and obesity in
offspring. He posited that these diseases had their roots, at least in
part, in under- or over-nutrition during pregnancy. If a pregnant woman
is under-nourished, her infant is prone to low birth weight with a rapid
“catch-up” gain in body fat later when exposed to plentiful food. If a
pregnant woman is over-nourished, her infant is prone to high birth
weight and a booming growth trajectory that increases the risk of
obesity later in life.
The amount of nutrients provided to a developing fetus, as well as
the type of nutrients, appears to chemically modify genes that
predispose a child to obesity and obesity-related diseases, said
Devaskar, whose own research on the subject resulted in her election to
the prestigious Institute of Medicine in 2012. Her current research
focuses on whether or not it’s possible to further modify those genes to
reverse the propensity to gain weight. “In the fetus, the organs are
still developing,” she explained. “It’s a critical window of
development, and it’s very plastic at that time. Any insult — whether
it’s from diet, drugs or toxins — creates a permanent mark that lasts
for one’s lifetime. The hypothalamus — the part of the brain governing
metabolism and hunger — is already programmed. The infant is used to
seeing so much nutrition coming from the mother. These children are
ever-hungry; they are born hypersensitive to high-calorie foods. Their
insulin sensitivity is low, so they are at high risk for developing
diabetes, obesity and heart disease.”
In 2009, the Institute of Medicine issued revolutionary new
guidelines to begin to address obesity in pregnancy. The group put
tighter limits on weight gain in pregnancy, warning doctors to help
their patients stay within a healthy range and even strictly limit
weight gain in obese pregnant women to 11 to 20 pounds.
“It’s a major change,” said Dr. Aisling Murphy, assistant professor
in the Division of Maternal-Fetal Medicine. “More recent data have
suggested that obese women really don’t need to be gaining as much
weight as women who enter pregnancy at a normal weight.”
Moreover, doctors are encouraging pregnant women to exercise —
something many women had been fearful of doing. “Sometimes, women are
under the impression that they shouldn’t be walking or going to the gym
when they are pregnant. That is not the case,” Murphy said. “They really
should be active.”
In addition to the risk of fetal programming, obesity during
pregnancy is linked to several other potential complications. The
chances of developing both hypertension and gestational diabetes are
higher in pregnant women who are obese. About 7 percent of pregnant
women in the United States develop gestational diabetes. Studies show
that these women have an increased likelihood of developing type 2
diabetes later in life. In essence, gestational diabetes often isn’t a
“temporary” condition that goes away after childbirth.
Obesity during pregnancy also raises the risk of some types of birth
defects and other complications, such as an increased risk of Cesarean
section or complications during childbirth, Murphy noted.
While two decades ago, few pregnant women were given extra resources
and support they needed to manage weight gain, overweight or obese women
who are planning to have children are now encouraged to seek
pre-conception counseling, where they are given advice and resources to
help them lose weight before becoming pregnant. And pregnant women who
are obese are typically referred to a registered dietician for
assistance with a healthy diet. Breastfeeding for at least six months is
highly recommended to help the mother lose weight.
“If we can take care of young women before pregnancy and during
pregnancy, we will end up with a healthier society, and it will bring
down health care costs dramatically,” Dr. Devaskar said.