How Birth Weight Affects Your Risk for Obesity

How birth weight affects your risk for obesityIt’s no secret that genetics impact the risk of obesity, but genetics aren’t destiny. Environmental factors play a role in whether or not those genes are fully expressed. These environmental influences may extend as far back as in utero as more research reveals that birth weight has an impact on whether or not a person gains too much weight later in life.

 Birth Weight and Obesity

A meta-analysis published in Obesity Review analyzed 20 studies looking at birth weight and obesity. As a group, these studies showed a link between higher birth weights and a greater risk for obesity later in life. Babies who weighed 8.8 pounds or more at birth were at significantly higher risk for obesity during childhood and early adulthood. Just as concerning is the fact that babies with higher birth weights had a greater risk for other health problems later in life including type 2-diabetes.

Prenatal influences have a greater impact than previously thought on a baby’s future risk of becoming obese, and some of these factors moms-to-be have control over. As the Harvard School of Public Health points out, there are other prenatal factors that affect an unborn baby’s risk of weight and health problems later in life. These include how much weight a woman gains during pregnancy, pregnancy blood sugar levels, smoking and diet.

Women who gain more weight during pregnancy have a greater risk of delivering infants with more body fat, setting the stage for future weight problems. Mom’s blood sugar levels play a role too. Women who develop gestational diabetes and have higher blood sugar levels during pregnancy give birth to babies that weigh more. Even though smoking increases a woman’s risk of delivering a baby of low-birth weight, a number of studies show that babies born to moms who smoked during pregnancy have a 50% greater risk for childhood obesity.

A Calculator to Predict the Risk of Obesity?

Based on some of these parameters including a baby’s body weight, researchers at the Imperial College of London have developed a calculator to predict a baby’s risk for becoming obese later in life. To use the calculator, parents enter the baby’s birth weight, information about the mom’s smoking habits during pregnancy, BMI (body mass index) of both parents and the occupation of the mom. Based on these factors, the calculator reveals the percent likelihood of a baby becoming obese later in life.

How is this useful? Even though it’s too late to alter some of these factors, babies at high risk for obesity can be identified early so parents can take steps to lower the risk through diet and activity level. The sooner parents start the better it is for the child from a health and weight standpoint.

Other Factors That Affect a Child’s Risk for Future Obesity

What happens after birth also affects a baby’s risk for weight problems later on. Some research shows moms can reduce the risk of a baby becoming obese by breastfeeding – the longer the better. The risk drops for each additional month that a mom breastfeeds. The link between lack of sleep and obesity seen in adults seems to hold true for babies too. One study showed that infants who slept less than 12 hours a day were at greater risk for weight problems during infancy.

Preventing Obesity Starts Early

Genetics and early environmental influences play a key role in a baby’s future risk of obesity. Moms-to-be may be able to reduce the risk of a baby becoming obese by limiting weight gain during pregnancy, not smoking and controlling blood sugar levels. Once the baby is born, breastfeeding and ensuring the baby gets enough sleep can further lower the risk for weight problems during childhood and early adulthood. The roots of obesity start early – even earlier than most people realize. That’s why it’s important to identify a susceptibility towards obesity early and take steps to lower the risk.



Obes. Rev. Jul; 12(7).

The Journal of Family Practice. June 2008 • Vol. 57, No. 6: 409-410.

WebMD. “Too Much Pregnancy Weight Linked to Baby’s Obesity Risk”

Harvard School of Public Health. “The Obesity Prevention Source”


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