Influenza Infection, Vaccination During Pregnancy Have No Effect on Common Maternal Outcomes

SAN FRANCISCO, CA—In a cohort of pregnant women, no associations were found between the 2010–2011 seasonal influenza infection or vaccination and four common maternal outcomes—gestational hypertension, preeclampsia/eclampsia, gestational diabetes, and chorioamnionitis—a prospective study concluded at IDWeek 2013.

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“Although the 2009 H1N1 influenza pandemic brought renewed awareness of the impact of influenza during pregnancy, few epidemiologic studies have examined the association between seasonal influenza infection and adverse maternal pregnancy outcomes,” reported Allison Naleway, PhD, of the Center for Health Research, Kaiser Permanente Northwest, Portland, OR, and colleagues.

As part of the Pregnancy and Influenza Project, the investigators enrolled 1616 pregnant women between December 2010 and May 2011. Each participant completed a weekly illness survey and agreed to have her electronic medical record screened daily for visits related to respiratory illness. If a woman presented with an illness that included fever and cough, respiratory specimens were collected and tested for influenza by real time reverse transcriptase polymerase chain reaction.

Influenza vaccination and incidence of gestational hypertension, preeclampsia/eclampsia, gestational diabetes, and chorioamnionitis were identified via electronic medical records.

“Outcomes were restricted to those occurring at ≥20 weeks gestation and after the respective influenza or vaccine exposure,” Dr. Naleway noted.

Among the cohort, 56 women (3%) tested positive for influenza and 924 (57%) received the 2010–2011 influenza vaccine while pregnant.

Rates of influenza infection and vaccination among women with and without the following conditions are listed in the table below.

 “Our findings are consistent with existing literature on influenza vaccine safety during pregnancy,” Dr. Naleway concluded. 



Influenza Infection

P value

Influenza Vaccination

P value

Gestational Hypertension

0.31

0.68

Yes (n=117)

6 (5%)

69 (59%)

No (n=1499)

50 (3%)

855 (57%)

Preeclampsia or Eclampsia

0.85

0.51

Yes (n=96)

3 (3%)

58 (60%)

No (n=1520)

53 (3%)

866 (57%)

Gestational Diabetes

0.49

0.17

Yes (n=192)

5 (3%)

101 (53%)

No (n=1424)

51 (4%)

823 (58%)

Chorioamnionitis

0.43

0.82

Yes (n=121)

2 (2%)

68 (56%)

No (n=1495)

54 (4%)

856 (57%)