title: Neonatal outcomes after influenza immunization during pregnancy: a randomized controlled trial.
abstract: BACKGROUND
  There are limited data about the effect of maternal influenza infection on fetuses and newborns. We performed a secondary analysis of data from the Mother's Gift project, a randomized study designed to test the effectiveness of inactivated influenza and pneumococcal vaccines during pregnancy.
  
  
  METHODS
  In the Mother's Gift project, 340 pregnant women in Bangladesh received either inactivated influenza vaccine or 23-valent pneumococcal polysaccharide vaccine (control). This study was performed from August 2004 through December 2005. We performed a secondary analysis of outcomes following maternal influenza immunization during two periods: when influenza virus was not circulating (September 2004 through January 2005) and when influenza virus was circulating (February through October 2005). We assessed gestational age, mean birth weight and the proportion of infants who were small for gestational age.
  
  
  RESULTS
  During the period with no circulating influenza virus, there were no differences in the incidence of respiratory illness with fever per 100 person-months among mothers and infants in the two groups (influenza vaccine: 3.9; control: 4.0; p > 0.9). The proportion of infants who were small for gestational age and the mean birth weight were similar between groups (small for gestational age: influenza vaccine 29.1%, control 34.3%; mean birth weight: influenza vaccine 3083 g, control 3053 g). During the period with circulating influenza virus, there was a substantial reduction in the incidence per 100 person-months of respiratory illness with fever among the mothers and infants who had received the influenza vaccine (influenza vaccine: 3.7; control: 7.2; p = 0.0003). During this period, the proportion of infants who were small for gestational age was lower in the influenza vaccine group than in the control group (25.9% v. 44.8%; p = 0.03). The mean birth weight was higher among infants whose mothers received the influenza vaccine than among those who received the control vaccine during this period (3178 g v. 2978 g; p = 0.02).
  
  
  CONCLUSIONS
  During the period with circulating influenza virus, maternal immunization during pregnancy was associated with a lower proportion of infants who were small for gestational age and an increase in mean birth weight. These data need confirmation but suggest that prevention of influenza infection in pregnancy can influence intrauterine growth.
  
  
  BACKGROUND
  ClinicalTrials.gov: NCT 00142389.
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA. mark.steinhoff@cchmc.org
authors.forename: Mark C
authors.initials: MC
authors.lastname: Steinhoff
authors.forename: Saad B
authors.initials: SB
authors.lastname: Omer
authors.forename: Eliza
authors.initials: E
authors.lastname: Roy
authors.forename: Shams
authors.initials: S
authors.lastname: El Arifeen
authors.forename: Rubhana
authors.initials: R
authors.lastname: Raqib
authors.forename: Caitlin
authors.initials: C
authors.lastname: Dodd
authors.forename: Robert F
authors.initials: RF
authors.lastname: Breiman
authors.forename: K
authors.initials: K
authors.lastname: Zaman
mesh_terms: D000328:Adult; D001459:Bangladesh; D001724:Birth Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D057194:Intention to Treat Analysis; D008297:Male; D016017:Odds Ratio; D022242:Pneumococcal Vaccines / Q000008:administration & dosage; D011247:Pregnancy; D011295:Prenatal Care; D012621:Seasons; D014611:Vaccination
chemical_list: D007252:Influenza Vaccines; D022242:Pneumococcal Vaccines