712. Impact of Hospitalization of Pregnant Women for Influenza Like Illness (ILI) On Infant Outcomes
Session: Abstracts: Virology
Friday, October 22, 2010

Analysis of neonatal outcome data from the Bangladesh RCT of  influenza vs pneumococcal vaccine during pregnancy demonstrated an increased proportion of small for gestational age (SGA) infants and lower mean birth weights among babies born to mothers not protected by influenza vaccine. This suggests that prevention of influenza in pregnancy results in improved fetal growth (Steinhoff et al, PAS, May 2010). Evidence for an influenza effect on fetal outcome in high resource regions is lacking. We compared outcomes of infants born to women with and without  hospitalization for ILI over a 10 year period in Nova Scotia (NS) Canada using previously described data that showed increased risk of ILI hospitalization in influenza season (CMAJ 2007; 176: 463–468).


Using the NS Perinatal database, neonatal outcomes among singletons were compared between mothers with or without admission for ILI during pregnancy. Multivariate logistic regression was used to examine infant outcomes, adjusting for  maternal high risk status and other potential confounders.


Neonatal outcomes in mothers with or without admission for ILI during pregnancy:

Outcome among singletons


Any hospital adm for ILI during the pregnancy



RR (95% CI)



RR (95% CI)



n (%)



n (%)

Peri /post-neonatal death

4 (0.8)

996 (0.7)

1.09, 0.41-2.92

0.94, 0.34-2.64

Low birth weight(<2,500 g)


28 (5.7)

6035 (4.6)

1.27, 0.87-1.86

1.05, 0.62-1.77

Small for gestational age


62 (13.0)

12594 (9.7)

1.39, 1.06-1.82

1.35, 1.03-1.76

Preterm (<37 weeks)


31 (6.3)

7159 (5.4)

1.18, 0.82-1.70

0.98, 0.68-1.41

Neonatal morbidity


44 (9.0)

6488 (4.9)

1.92, 1.40-2.61

1.78, 1.29-2.46

Mean birth weight



(SD: 593.8)


(SD: 583.8)

ß = -93.71


ß = -60.14



These analyses extend findings of the Bangladesh RCT SGA findings to apply to infants born to women in a high resource country. While supporting a negative impact of influenza on neonatal birthweight, our findings are indirect as ILI was not confirmed as influenza. More research is needed to determine whether influenza vaccine during pregnancy in high resource regions can decrease rates of ILI admissions among pregnant women and their infants and decrease rates of SGA babies.

Subject Category: I. Adult and Pediatric Vaccines

Shelly McNeil, MD , Canadian Center for Vaccinology, IWK Health Centre, Dalhousie University, Halifax, NS, Canada
Linda Dodds, PhD , Perinatal Epidemiology Research Unit, IWK Health Centre, Dalhousie University, Halifax, NS, Canada
Deshayne Fell , Ottawa Hospital Research Institute, Ottawa, ON, Canada
Mark C. Steinhoff, MD, FIDSA , Global Health Center, Cincinnati Children's Hospital, Cincinnati, OH
Noni MacDonald, MD , Pediatrics, Dalhousie University, IWK Health Centre, Halifax, NS, Canada


S. McNeil, Yes
glaxoSmithKline: Grant Investigator, Research support
sanofi pasteur: Grant Investigator, Research support
Wyeth/Pfizer: Grant Investigator, Research support

L. Dodds, None

D. Fell, None

M. C. Steinhoff, None

N. MacDonald, None

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