Figure 5.

Path analysis of maternal weight gain during pregnancy estimating direct and indirect (through early-life tumor necrosis factor [TNF]-α) paths to childhood asthma. Multiplying the standardized regression coefficient for the relation of maternal weight gain to early-life TNF-α (0.18) by the coefficient for early-life TNF-α to asthma (0.18) equals 0.03, and thus the indirect path represents 15% (0.03/[0.17 + 0.03]) of the total (direct plus indirect) path. Variables are entered dichotomously (1/0): maternal weight gain as upper tertile compared with two lower tertiles; early-life TNF-α as high/high versus other; childhood asthma as physician-diagnosed active asthma (ages 2–9) or not.