Table 2.

Age at menarche and risk of MS, results from well-designed epidemiological investigations.

Author	Year	Population	Study	Design	Cases/controls*	Mean age at menarche			Regression model
						Cases	Controls	P-value	Estimate (95%CI)	P-value	Covariates included
Ramagopalan et al.	2008	Caucasian	case-control study	Population-based	4,472/658	12.4 (1.29)	12.6 (1.33)	0.00017	0.90 (0.84–0.95)	0.00063	Age
Nielsen et al.	2016	Caucasian	cohort study	Population-based	226/77,104	13.0 (1.5)	13.3 (1.4)	0.002	0.89 (0.81–0.98)	Not reported	BMI, socio-occupational status, age at first pregnancy, parity, smoking and alcohol intake.
Rejali et al.	2016	Caucasian (Iran)	Case-control study	Hospital-based	200/200	12.96 (1.43)	13.48 (1.49)	0.0001	0.78 (0.68–0.90)	0.001	Age, marital status, residential area, family history of MS, other autoimmune diseases and history of viral diseases in childhood.
Salehi et al.	2018	Caucasian (Iran)	Case-control study	Population-based	399/541	13.14 (1.46)	13.36 (1.67)	0.042	0.90 (0.82–0.98)	0.018	Age, marital status and education.

^*all subjects were females.