. 2013 Dec 4;8(12):e81070. doi: 10.1371/journal.pone.0081070

Table 4. Analyses of 1^st versus later-borns with Adjustment for Mother's age and number of siblings.

	Adjusted for maternal age at child's birth		Adjusted for number of siblings (as of March 31^st 2011)
Birth order	Relative Incidence Ratio (95% CI)	RIR p-value	Relative Incidence Ratio (95% CI)	RIR p-value
2-month Vaccination
2^nd or higher	1 (Ref)		1 (Ref)
1^st	1.33 (1.15–1.54)	<0.0001	1.53 (1.26–1.86)	<0.0001
4-month vaccination
2^nd or higher	1 (Ref)		1 (Ref)
1^st	1.67 (1.42–1.97)	<0.0001	1.71 (1.38–2.13)	<0.0001
6-month vaccination
2^nd or higher	1 (Ref)		1 (Ref)
1^st	1.25 (1.06–1.46)	0.0063	1.36 (1.11–1.67)	0.0032
12-month vaccination
2^nd or higher	1 (Ref)		1 (Ref)
1^st	1.09 (1.01–1.19)	0.0370	1.20 (1.07–1.33)	0.0013

Table 4. Analyses of 1st versus later-borns with Adjustment for Mother's age and number of siblings.