Table 5. Association between microcephaly and laboratory confirmation of Zika virus infection.

	Cases Positive/Total	Controls Positive/Matched	Odds ratio 95% CI)
Serum or cerebrospinal fluid samples or macerated tissue*
All cases	32/91 (35%)	0/173	87·0 (15·6 to ∞ )
All cases adjusted†	-	-	73·1 (13·0 to ∞ )
Cases categorized by severity‡
Severe (<-3SD)	19/26 (73%)	0/51	52·4 (9·1 to ∞ )
Not (between -2SD and lower than -3SD)	13/65 (20%)	0/122	33·7 (5·6 to ∞ )
Cases categorized by brain imaging findings‡
Abnormal	12/29 (41%)	0/53	32·2 (5·3 to ∞ )
Normal	11/50 (22%)	0/97	29·3 (4·8 to ∞ )

^*Positive at qRT-PCR or Zika specific IgM.

^†ORs adjusted by smoking during pregnancy, acellular pertussis vaccine (Tdap) during pregnancy and skin color.

^‡ORs are crude in subgroup analysis due to small numbers.