Table 2.

Crude Prevalence Rates (per 100 Births) of Preterm and Small-for-Gestational-Age Births Among Study Participants (n = 46,549) by Monovalent Influenza Vaccine Status, Vaccine Safety Datalink Cohort, 2009–2010

MIV Status	No. of Pregnancies	SGA Birth (<10th Percentile)	Preterm Birth (<37 Weeks)
No MIV	27,392	8.6	8.2
Received MIV
Any time during pregnancy	19,157	8.3	6.1
First trimester	6,788	7.5	6.8
Second trimester	7,096	8.9	6.9
Third trimester	5,244	8.5	4.2

Abbreviations: MIV, monovalent influenza vaccine; SGA, small-for-gestational-age.