Background: Different pathways likely underlie the association between early weight gain and cardiovascular disease risk. We examined whether birth weight for length relationship and weight gain up to 2 years of age are associated with lipid profiles and blood pressure ( BP ) in early adolescence and determined whether childhood adiposity mediates these associations. Methods and Results: Data from QUALITY (Quebec Adipose and Lifestyle Investigation in Youth), a cohort of white children with parental history of obesity, were analyzed (n=395). Sex‐specific weight for length z scores from birth to 2 years were computed. Rate of postnatal weight gain was estimated using individual slopes of weight for length z ‐score measurements. Percentage of body fat was measured at 8 to 10 years. Fasting lipids and BP were measured at 10 to 12 years. Using path analysis, we found indirect effects of postnatal weight gain, through childhood adiposity, on all outcomes: Rate of postnatal weight for length gain was positively associated with childhood adiposity, which in turn was associated with unfavorable lipid and BP levels in early adolescence. In contrast, small beneficial direct effects on diastolic BP z scores, independent of weight at other time points, were found for birth weight for length (β=−0.05, 95% CI , −0.09 to −0.002) and for postnatal weight gain (β=−0.02, 95% CI , −0.03 to −0.002). Conclusions: Among children with at least 1 obese parent, faster postnatal weight gain leads to cardiovascular risk factors in early adolescence through its effect on childhood adiposity. Although heavier newborns may have lower BP in early adolescence, this protective direct effect could be offset by a deleterious indirect effect linking birth weight to later adiposity.

In this issue of the Journal, Savitz and Wellenius (Am J Epidemiol. 2023;192(4):514–516) discuss the contribution of cross-sectional studies to causal inference when the data are used to address etiological research questions. We elaborate on their thoughts with a discussion of the conditions needed for addressing etiology with the cross-sectional design, using a modern causal inference lens.

Background: Exergaming is technology-driven physical activity (PA) which, unlike traditional video game play, requires that participants be physically active to play the game. Exergaming may have potential to increase PA and decrease sedentary behavior in youth, but little is known about sustained exergaming. Objective: The objectives of this study were to describe the frequency, correlates, and predictors of sustained exergaming. Methods: Data were available in AdoQuest (2005-11), a longitudinal investigation of 1843 grade 5 students in Montréal, Canada. This analysis used data from grade 9 (2008-09) and 11 (2010-11). Participants at Time 1 (T1; mean age 14 years, SD 0.8 ) who reported past-week exergaming (n=186, 19.1% of AdoQuest sample) completed mailed self-report questionnaires at Time 2 (T2; mean age 16 years, SD 0.8). Independent sociodemographic, psychological, and behavioral correlates (from T2)/predictors (from T1 or earlier) were identified using multivariable logistic regression. Results: Of 186 exergamers at T1, 81 (44%) reported exergaming at T2. Being female and having higher introjected regulation (ie, a type of PA motivation indicative of internalizing PA as a behavior) were independent correlates. None of the predictors investigated were associated with sustained exergaming. Conclusions: Almost half of grade 9 exergamers sustained exergaming for 2 years. Exergaming may be a viable approach to help adolescents engage in and sustain PA during adolescence. Sex and PA motivation may be important in the sustainability of exergaming.