乌鸦传媒

Mothers' dietary and television-watching habits had an effect on the body mass index (BMI) and lifestyle patterns of their young children, according to a trajectory modeling study.

In more than 400 children and mothers followed for 5 years, the kids of mothers who followed a healthy dietary pattern high in fruits and vegetables were more likely to have healthy lifestyle patterns themselves and a BMI in the normal range (OR 1.22, 95% CI 1.01-1.47), reported Miaobing Zheng, PhD, of the School of Exercise and Nutrition Sciences at Deakin University in Geelong, Australia.

In addition, as shown in the study online in , the children of mothers who reported watching more than 130 minutes of television a day were more likely to adopt unhealthy lifestyle patterns and have a higher BMI (OR 2.55, 95% CI 1.13-5.72), as were the children of mothers who had a pre-pregnancy BMI over 25 (OR 2.50, 95% CI 1.31-4.75).

"It is conceivable that unhealthy maternal lifestyle behaviors (i.e., dietary patterns and TV viewing) may predispose their child to have unhealthy LPs [lifestyle patterns] in early childhood," Zheng's team wrote. However, child sex, breastfeeding duration, and maternal physical activity were not significantly associated with children's lifestyle patterns.

In a statement accompanying the study, an expert not involved in the research suggested the children were copying the behavior of their mothers: "Young children learn by imitating that which they see daily," said Liliana Aguayo, PhD, of the Hubert Department of Global Health at Emory University in Atlanta. "There is no doubt that children copy the behaviors observed in the presence of parents: healthy and unhealthy. Evidence from this study highlights the importance of early childhood as a critical period for development of obesity. More research is needed to identify effective approaches to simultaneously address parent and child health behaviors."

The study was the first to use multitrajectory modeling to examine longitudinal relationships between the lifestyle practices of mothers and young children, the researchers said. "Multitrajectory modeling identifies groups of individuals following similar trajectories across multiple variables, enabling the estimation of the relationships between two or more longitudinal variables that are jointly evolved over time."

The study included 439 children who were part of the Melbourne Infant Feeding Activity and Nutrition Trial program. All the data were self-reported by mothers via questionnaires. Clinical and demographic information were gathered at baseline and at 18 months. Data on lifestyle factors including diet, physical activity, and time spent watching television for mothers and children were gathered at 18, 42, and 60 months.

Based on this information, the researchers identified three "trajectory groups" for the children:

• Group 1 included approximately 30% of the children and was characterized by unhealthy lifestyle patterns and low BMIs

• Group 2 included 53% of the children and was characterized by healthy lifestyle patterns and mid-range BMIs

• Group 3 included 17% of the children and was characterized by unhealthy lifestyles and higher BMIs

It may seem counterintuitive that about 30% of the children had both unhealthy lifestyle practices and lower BMIs, Zheng's team noted. "Yet several cross-sectional studies have documented an inverse association between unhealthy LPs and obesity. It is likely that an unhealthy lifestyle with poor diet quality, more screen time, and less outdoor time does not necessarily equate to a short-term positive energy balance and in turn body weight gain."

Previous studies have shown that young children have a better ability to compensate energy intake than older children or adults do, the researchers said. They also noted that, in their study, the children with unhealthy lifestyle practices but lower BMIs had the lowest mean birth weight and lowest percentage of mothers with overweight and obesity, which may have contributed to the lower BMI scores in this group.

"The potential early programming effects of lower child birth weight and maternal pre-pregnancy BMI may protect this group of children from developing a high BMI z score trajectory," the team suggested. "Furthermore, the coexistence of unhealthy LP and normal BMI z score trajectories in some children may explain a lack of significant associations between LPs and obesity in some studies."

A chief limitation of the study was the reliance on self-reports from the mothers, meaning that the data was therefore subject to reporting errors and recall bias, Zheng's group said. Another limitation was the high proportion of highly educated mothers in the study, which ranged from 38% in Group 1 to 64% in Group 2. The results therefore might not be generalizable to the national population, the researchers noted.

Comment