The association of parity/live birth number with incident type 2 diabetes among women: over 15 years of follow-up in The Tehran Lipid and Glucose Study

Table 3 Multivariable hazard ratios (HR) and 95% confidence intervals (CI) of incident T2DM by number of parity until phase IV (2008–2011): Tehran Lipid and Glucose Study

	E/N	Model 1		Model 2		Model 3		Model 4		Model 5
	E/N	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value
Parity (continuous variable)
Per each additional	323/2492	1.12 (1.04–1.19)	0.001	1.11 (1.04–1.19)	0.003	1.10 (1.03–1.18)	0.007	1.06 (0.99–1.13)	0.118	1.06 (0.98–1.13)	0.126
Number of parity
1	10/173	1		1		1		1		1
2	54/597	1.51 (0.77–2.97)	0.229	1.51 (0.77–2.97)	0.234	1.49 (0.76–2.93)	0.249	1.42 (0.72–2.80)	0.307	1.40 (0.71–2.75)	0.335
3	72/624	1.74 (0.89–3.38)	0.104	1.72 (0.88–3.36)	0.114	1.67 (0.85–3.28)	0.134	1.50 (0.77–2.95)	0.235	1.45 (0.74–2.85)	0.276
≥ 4	187/1098	2.16 (1.11–4.20)	0.023	2.11 (1.08–4.13)	0.029	2.03 (1.03–3.98)	0.040	1.55 (0.79–3.05)	0.200	1.47 (0.75–2.89)	0.267
P value for trend			0.006		0.010		0.017		0.298		0.432

Model 1: Adjusted for age. Model 2: Adjusted for age, education level, low physical activity, family history of diabetes, systolic and diastolic blood pressure, and anti-hypertensive medications usage. Model 3: Model 2 + further adjusted for history of macrosomia, preeclampsia, and oral contraceptive pill (OCP) usage. Model 4: Model 3 + further adjusted for body mass index and waist circumference. Model 5: Model 4 + further adjusted for triglyceride/ high-density lipoprotein cholesterol. T2DM: type 2 diabetes mellitus; E: event; N: number

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