TABLE 2.

Mediation Analysis: Effect of IL1RN SNP rs2637988 Allele Status on Days Gestation at Birth Through IL-1Ra Production

Predictor		M: IL-1Ra productiona				Y: Gestation at birthb, c
		Coeff.	(SE)	p		Coeff.	(SE)	p
X: IL1RN SNP rs2637988 allele status	a1	0.33	(0.322)	.31	c′1	0.56	(0.280)	.05
M: IL-1Ra production		---	---	---	b1	0.02	(0.094)	.85
Covariate: maternal education		0.20	(0.487)	.69		0.31	(0.421)	.47
Covariate: insurance status		-0.67	(0.458)	.15		0.62	(0.400)	.13
Constant	b0	5.17	(0.447)	< .001	b0	2.98	(0.620)	< .001

Note. n = 89. a₁ = coefficient assigned to X in the estimation of M; b₁= coefficient assigned to M in the estimation of Y; c′₁ = coefficient assigned to X in the estimation of Y; Coeff. = coefficient; b₀= intercept; IL = interleukin; M = mediator; Ra = receptor antagonist; SE = standard error; SNP = single nucleotide polymorphism; X = predictor.

^aR² = .09, p = .04.

^bsquare root of reflected days gestation (i.e., -(days gestation) + 288 + 1).

^cR² = .07, p = .18.