Study of factors influencing susceptibility and age at onset of type 1 diabetes: A review of data from Continental Italy and Sardinia

Table 2 Maternal age at conception in consecutive newborns and in children with type 1 diabetes in Continental Italy and in Sardinia

	Sardinia		Continental Italy
	Consecutive newborns	Children with T1D	Consecutive newborns	Children with T1D
% proportion with maternal age > 32 yr	32.70%	89.30%	19.10%	32.20%
Total n	5460	187	792	90
χ2 test of independence
χ2	253.705		7.821
df	1		1
P	< 10-6		0.005
OR analysis
OR	17.191		2.018
95%CI	10.569-24.396		1.234-3.331

Three way contingency table analysis by a log linear model: x = T1D vs controls; y = maternal age (≤ 32 yr vs > 32 yr); z = Continental Italy vs Sardinia. x, y and z interaction: G = 45.703; df = 1; P < 0.0001. T1D: Type 1 diabetes.