Table 1.

Baseline Comparisons Between Females Exposed and Unexposed to Trivalent Inactivated Influenza Vaccine During Pregnancy

	Vaccinated n=74,292	Unvaccinated n=144,597	P
Age at pregnancy outcome (y)			.36
Younger than 20	2,753(3.7)	5,402 (3.7)
20–34	54,421 (70.6)	102,389 (70.8)
35 or older	19,118 (25.7)	36,806(25.5)
Medical care during first trimester	65,978 (88.8)	124,806 (86.3)	<.001
Hospitalized prior to vaccine or index date	3983(5.4)	8209 (5.7)	.002
Preexisting comorbidities*
Pulmonary	4,672 (6.3)	6,557 (4.5)	<.001
Hypertension	1,766(2.4)	2,976(2.1)	<.001
Diabetes	1,336 (1.8)	1,865 (1.3)	<.001
Heart disease	883 (1.2)	1,362 (0.9)	<.001
Neurologic	388 (0.5)	669 (0.5)	.83
Rheumatologic	304 (0.4)	466 (0.3)	.06
Hypercoagulability	134 (.2)	210 (0.2)	.05
Any comorbidity	8,570(11.5)	12,953(9.8)	<.001
Preexisting pregnancy complications†
Hemorrhage in early pregnancy	6,577(8.9)	12,831(8.9)	.87
Gestational hypertension	1,083(1.5)	1,775(1.2)	<.001
Excessive vomiting	3,951(5.3)	7,874(5.5)	.21
Gestational diabetes	3,322 (4.5)	5,454(3.8)	<.001
Proteinuria	109(0.2)	214(0.2)	.94
Obesity	4,148(5.6)	7,459(5.2)	<.001
Any pregnancy complication	16,169 (21.8)	30,371(21.0)	<.001
Number of outpatient visits
Before vaccine or index date	5.1 ± 4.1	4.6 ± 4.0	<.001
After vaccine or index date	7.6 ± 4.9	6.8± 4.6	<.001
Poverty‡	13.0 ± .12	14.9± .13	<.001
Gestational age at delivery (wk)§	39.0 ± 1.62	39.0± 1.68	.50

Data are n (%) or mean ±standard deviation unless otherwise specified.

^*Diagnoses at inpatient, outpatient or emergency visits, from 6 months prior to estimated last menstrual period through the vaccination or index date.

^†Diagnoses at inpatient, outpatient or emergency visits from the estimated last menstrual period through the vaccination or index date.

^‡Percent of families in census tract with income below 150% of federal poverty level ± standard error

^§For pregnancies ending in a live birth, mean gestational age ± standard deviation