Table 3.

Incidence Rates and Adjusted Hazard Rate Ratios For Adverse Obstetric Events Occurring During Pregnancy or Postpartum Period After Trivalent Inactivated Influenza Vaccination

Outcome	Events After Vaccination Number of events (Rates per 1000 pregnancies)			Multivariable Analyses*
	Vaccinated	Unvaccinated	P	Adjusted Hazard Rate Ratio (95% CI)	P
Vaccinated in first trimester	n=21,107	n=40,738
Mild preeclampsia†‡§	657 (30.0)	1,249 (31.4)	.45	.94 (.86–1.04)	.22
Severe preeclampsia or eclampsia†‡§	364 (16.6)	617 (15.5)	.27	1.05 (.92–1.19)	.51
Vaccinated at 20 weeks or greater	n=38,038	n=74,192
Gestational hypertension†§	1,663(44.3)	3,046(41.9)	.053	1.04(.98–1.11)	.19
Gestational diabetes§	1,773(50.1)	3,925(57.0)	<.0001	.88(.83–.93)	<.001
Chorioamnionitis	1,615(42.9)	2,861(39.0)	.002	1.08(1.02–1.15)	.01
Puerperal infection§	363(9.5)	728(9.8)	.64	.96(.85–1.09)	.55
Venous complications§	21(.55)	63(.85)	.08	.64(.39–1.05)	.08
Pulmonary embolus§	11(.20)	17(.16)	.56	1.23(.58–2.64)	.59
Peripartum cardiomyopathy§	13(.24)	37(.35)	.24	.66(.35–1.24)	.20
Vaccinated in any trimester	n=74,292	n=144,597
Mild preeclampsia†‡§	2,338 (18.2)	4,422 (18.2)	.73	.97 (.93–1.02)	.30
Severe preeclampsia or eclampsia†‡§	1,189 (9.2)	2,293 (9.4)	.44	.95 (.88–1.02)	.14
Proteinuria†	400(5.3)	832(5.8)	.09	.88(.78–1.00)	.04
Urinary tract infection	1,905(25.5)	3,655(26.0)	.57	1.0(.94–1.05)	.91

CI, confidence interval.

Women vaccinated in the first trimester and their unexposed matches had a mean follow-up of 6.3 months; for women vaccinated at 20 weeks or greater and their unexposed matches, mean follow-up was 2.4 months; for women vaccinated in any trimester and their unexposed matches, mean follow-up was 4.1 months.

^*All outcomes adjusted for receipt of medical care in the first trimester, hospitalization prior to vaccination or index date, and poverty; additional adjustments were outcome specific.

^†Also adjusted for diabetes, gestational diabetes

^‡Also adjusted for proteinuria

^§Also adjusted for obesity