Permanently shedding pregnancy-related weight is a struggle for many women, but new research suggests it may be a far more significant challenge for very young mothers as they grow older. Understanding the differences in how pregnancy affects teenage mothers is important, said Tammy Chang, MD, MPH, “because as an obesity researcher, I’ve learned that it’s critical to prevent obesity in the first place, rather than try to treat the condition and the associated health issues after it is already a problem.”
Chang, a Robert Wood Johnson Foundation (RWJF) Clinical Scholar (2011-2013) and a family physician in the University of Michigan Health System, developed an interest in the impact of pregnancy on weight gain at different stages of life from observing trends she saw among her patients.
“I see a lot of teen moms in my practice. Over time, I noticed that they tended to gain more weight than is recommended during pregnancy,” explained Chang, adding that her patients are an ethnically diverse group of Black, White, and Hispanic women. “I wanted to understand if this had an impact on their weight in later life.”
The Effect of Early Pregnancy
Using 10 years of data from the National Health and Nutrition Examination Survey (NHANES), Chang and her colleagues assessed body mass index (BMI) in 5,256 women, ages 20-to-59. Each of the women in the nationally representative sample had given birth to at least one child, but they were not pregnant at the time of the survey. Teen birth was defined as having had a child between the ages of 13 and 19.
After controlling for variations in age, race, education, and number of children, Chang found that 44 percent of the women who had given birth as teens were obese as adults. Only 35 percent of the women who had given birth after age 19 had become obese later in life. The research is the first study to identify a connection between obesity and pregnancy early in life.
Chang’s article “Implications of Teen Birth for Overweight and Obesity in Adulthood” was published online, in draft form, in the April 2013 issue of the American Journal of Obstetrics & Gynecology and selected as an “editor's choice” for that edition. The final version of the study will be published in the July issue of the journal.
Understanding Young Women’s Bodies
Citing a possible link between the study’s findings and our nation’s ongoing obesity epidemic, Chang said, “even though it has gone down in recent years, the teen birth rate in the United States is still the highest in the developed world [34.3 births per 1,000 for girls ages 15-to-19, according to the Centers for Disease Control and Prevention 2010 data]. Our obesity rate is sky high as well, so we really need more research on the link between teen pregnancy and weight gain.”
While the study did not produce conclusive explanations for the early pregnancy/obesity connection, Chang explained that “our literature review found that when growing adolescent girls become pregnant, they accumulate fat very differently than adult women.”
In addition, “teen mothers are less likely to breast-feed,” she added, noting that breast-feeding helps women lose weight after giving birth. For health care providers, Chang suggested that they watch teen moms carefully to prevent them from gaining too much weight during pregnancy.
“Perhaps the other important lesson we learned,” Chang said, “is that adolescence is a very important period of a young woman’s life. It is a time when they need to learn to take care of themselves. Having to take care of someone else at such a young age makes that process more difficult.”