Rapid weight gain in pregnancy may play a key role in the development of excess fat tissue in female children and adolescents.
Nutritional science researchers analysed more than 300 pregnant women and followed their children from five to 14 years old. The researchers connected patterns of weight gain in pregnancy to patterns of their children’s body mass index (BMI), waist circumference and body fat percentage during childhood and early adolescence.
“We wanted to understand whether different weight change patterns during pregnancy impacted the child’s growth over time or the child’s potential to develop excess fat tissue,” said Beth Widen, assistant professor of nutritional sciences at UT Austin. “For boys, we didn’t really see that much of a difference in their patterns of weight and body size over time. But for girls, we saw some striking differences. This tells us there are differences between the sexes in this area of child growth.”
The new study conducted by researchers at The University of Texas at Austin was published in the journal Obesity.
Weight gain in pregnancy
Weight changes in pregnancy generally followed four distinct patterns in the study. One group of pregnant participants in the study lost weight during the first trimester, gained moderately during the second and showed rapid weight gain in the third trimester. A second group experienced slow weight gain in pregnancy across the three trimesters. A third group saw slow weight gain during the first trimester and moderate weight gain through the end of pregnancy. The final group experienced rapid weight gain in the first trimester, followed by slow weight gain during the second and moderate weight gain during the third.
The researchers found that girls born to the fourth group in this study – individuals with weight gain in pregnancy at the start and end – had the highest BMI measurements, the largest waist circumferences, and the highest body fat percentages from ages five to 14. Conversely, girls born to study participants from the first group – individuals who lost weight in the first trimester and gained moderately in the second trimester and rapidly in the third – had the lowest BMI, waist circumference and body fat percentages in the study.
Weight gain in pregnancy and childhood body composition patterns emerged with boys in the study. Widen speculated that this may be due to differences between the sexes in growth and development in addition to differences in how boys and girls respond to prenatal exposures.
The researchers emphasised that finding a pattern in children’s body composition from weight gain in pregnancy and across childhood is not the same as detecting causation, so further research is needed.
“This study shows us that there may be sex differences in child body composition based on what they are exposed to in utero,” Widen said. “But really, we believe there is only a small portion of weight gain in pregnancy that can be consciously changed – specifically among fat tissue – since much of the weight change is necessary to support the pregnancy. It is possible that these findings are just the start of research that can help us further understand risk factors for childhood obesity and may help us develop more individualised weight gain guidelines that support pregnant people.”