Table 4:

Mediation analysis – Leptin as a mediator in the relationship between weight gain during first year of life and ASD risk

	Total Effect, OR (95% CI)	Direct Effect, OR (95% CI)	Indirect effect, OR (95% CI)	Percentage mediated by early childhood leptin (%)
Unadjusted (Total N=476; ASD=32)
On track	Ref
Slow	1.92 (0.52, 7.11)	1.93 (0.52, 7.16)	0.99 (0.81, 1.22)
Rapid weight gain	1.39 (0.38, 5.11)	1.17 (0.32, 4.32)	1.19 (0.93, 1.52)
Extreme rapid weight gain	2.80 (1.08, 7.28)	2.22 (0.84, 5.87)	1.26 (0.95, 1.67)
Model 1: Adjusted
On track	Ref
Slow	1.80 (0.44, 7.47)	1.81 (0.44, 7.49)	1.00 (0.72, 1.39)
Rapid weight gain	1.06 (0.23, 4.85)	0.82 (0.18, 3.78)	1.29 (0.89, 1.87)
Extreme rapid weight gain	1.80 (0.55, 5.90)	1.15 (0.34, 3.88)	1.56 (1.01, 2.42)	76.03

Model 1: Adjusted for child’s sex, race, breast-feeding category, age of leptin measurement, follow-up time and gestational age

A causal inference framework was used to estimate ORs and 95% CI for total, direct and indirect effects. A logistic regression model was fit using categorical exposure (weight gain during infancy) and continuous mediator (leptin).