Changes in maternal BMI significantly influenced the likelihood of obesity in children, a recent study showed.
“We looked at records from more than 350,000 moms and their children to study how a mom’s weight before and after pregnancy might affect their child’s likelihood of becoming obese,” Karen Wong, MD, a physician at Epic Research, told Healio.
The researchers noted that although prior research has established associations between maternal BMI before pregnancy and risk for obesity in children, “less is known about whether postpartum BMI changes can influence that risk.”
In the study, Wong and colleagues analyzed the change in maternal BMI from before pregnancy to at least 6 months after pregnancy, and if children reached an obese BMI category after the age of 2 years.
They adjusted for the mothers’ age, race, history of type 2 diabetes, BMI category before pregnancy and social vulnerability, as well as for gestational age at birth and the sex of the child.
The researchers found that children born to mothers with obesity both before and after pregnancy had a 146% increased likelihood of obesity vs. children born to mothers without obesity. Meanwhile, children born to mothers with overweight both before and after pregnancy had a 53% increased likelihood of obesity.
Wong and colleagues noted that if a mother had obesity before pregnancy but overweight after it, the likelihood of obesity in the child was reduced by 51 percentage points to 95%.
Similarly, children whose mothers who were overweight before pregnancy but not overweight after had a 45% likelihood of obesity — an 8 percentage point reduction.
A child’s likelihood of obesity increased by 30 percentage points to 33% if a mother went from not having overweight before pregnancy to having overweight after, and by 33 percentage points to 83% if a mother went from having overweight to having obesity.
“Helping all moms reach or maintain a healthy weight after pregnancy has many known benefits for the mom, and it might also decrease their child's risk of obesity,” Wong said.
She said there are several potential explanations for the findings, “including genetics, diet, physical activity, and environmental and social factors.”