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. 2011 Aug 5;6(8):e23049. doi: 10.1371/journal.pone.0023049

Table 2. Adverse events following 2009 H1N1 vaccines among pregnant women, November 1, 2009–August 31, 2010, by vaccine type and timing of vaccination.

Adverse event Timing of vaccinationa
First trimester Second trimester Third trimester
Unadjuvanted vaccine MF59®-adjuvanted vaccine Unadjuvanted vaccine MF59®-adjuvanted vaccine Unadjuvanted vaccine MF59®-adjuvanted vaccine
(n = 10) (n = 4) (n = 15) (n = 1) (n = 5) (n = 2)
Pregnancy-specific
Spontaneous abortion 9 1 6 0 0 0
Stillbirth 0 0 7 1 2 1
Neonatal death 0 0 2b 0 1c 1d
Nonpregnancy-specific 1e 1f 0 0 2f 0
Inadvertent immunization 0 2g 0 0 0 0
a

First trimester, 0–13 weeks; second trimester, 14–27 weeks; third trimester, ≥28 weeks of pregnancy.

b

The causes of death were fetal anemia and hydrops fetalis (n = 1) and preterm delivery at 21st week of gestation (n = 1).

c

The cause of death was hydrops fetalis caused by α-thalassemia.

d

The cause of death was cerebral hemangioblastoma with intracranial hemorrhage.

e

The patient received the 2009 H1N1 vaccine at 10th week of pregnancy and developed allergic vasculitis 10 days after vaccination. She was treated with systemic corticosteroids, which led to an elective termination of pregnancy due to perceived risk of corticosteroid on fetal development.

f

The reported adverse events were generalized rash for the MF59®-adjuvanted vaccine; and numbness of fingers (n = 1) and dizziness, tremor, and rhinorrhea (n = 1) for the unadjuvanted vaccine.

g

One of the pregnant women delivered a healthy male infant at 39th week of gestation. The outcome for the other pregnant woman was not specified in the report.