Outcomes of infants born to women with influenza A(H1N1)pdm09

Abstract

Background: Pregnant women with influenza are more likely to have complications, but information on infant outcomes is limited. Methods: Five state/local health departments collected data on outcomes of infants born to pregnant women with 2009 H1N1 influenza reported to the Centers for Disease Control and Prevention from April to December 2009. Collaborating sites linked information on pregnant women with confirmed 2009 H1N1 influenza, many who were severely ill, to their infants’ birth certificates. Collaborators also collected birth certificate data from two comparison groups that were matched with H1N1-affected pregnancies on month of conception, sex, and county of residence. Results: 490 pregnant women with influenza, 1,451 women without reported influenza with pregnancies in the same year, and 1,446 pregnant women without reported influenza with prior year pregnancies were included. Women with 2009 H1N1 influenza admitted to an intensive care unit (ICU; n = 64) were more likely to deliver preterm infants (<37 weeks), low birth weight infants, and infants with Apgar scores <=6 at 5 min than women in comparison groups (adjusted relative risk, aRR = 3.9 [2.7, 5.6], aRR = 4.6 [2.9, 7.5], and aRR = 8.7 [3.6, 21.2], for same year comparisons, respectively). Women with influenza who were not hospitalized and hospitalized women not admitted to the ICU did not have significantly elevated risks for adverse infant outcomes. Conclusions: Severely ill women with 2009 H1N1 influenza during pregnancy were more likely to have adverse birth outcomes than women without influenza, providing more support for influenza vaccination during pregnancy.

Moderately pathogenic maternal influenza A virus infection disrupts placental integrity but spares the fetal brain

“…While we did not record placental and fetal weights, it is likely that a similar growth retardation is present in our model considering the substantial body weight reduction in pregnant dams after correcting for litter size. Indeed, rates of intrauterine growth restriction leading to lower birth weight infants are increased following gestational IAV infection in humans 52 .…”

“…Nevertheless, the lack of transcriptional changes in immune, barrier integrity, and neurodevelopmental genes here suggests that offspring neurological outcomes, if present, are likely to be more mild than what has previously been described in the H1N1 A/NWS/33 infection model [65][66][67][68] . Indeed, recent epidemiological data indicates that severe IAV infection during pregnancy significantly elevated the risk of adverse infant outcomes, while less severe infection did not 52 . Our data support a model in which a moderately pathogenic IAV infection is below the severity threshold necessary to induce detrimental effects on fetal brain immune equilibirum.…”

Influenza hospitalizations in children under 1 year old in Spain: the importance of maternal immunization

“…More recently, it has been shown that children under 6 months of age usually only develop a fever but are very likely to be hospitalized with a favorable outcome in most cases, as described by Bender et al 13 Most published articles insist and conclude that influenza rates in infants can be reduced by adopting a cocoon strategy that involves vaccinating close contacts and mothers during pregnancy and even during lactation for those not previously vaccinated. [14][15][16][17][18][19][20][21] It is necessary to promote and stimulate vaccination in all pregnant women, 22 which, in Spain, barely reaches 50% coverage in the best scenario. López-Medina et al 23 showed that during the 2009 pandemic, most Spanish newborns developed a community-acquired influenza infection, which was found to be associated with hospital admissions and favorable short-term results.…”

Influenza Virus and Vaccination

“…Infants born to mothers who were vaccinated against influenza may have a decreased rate of preterm birth, low birthweight, and stillborn birth, although establishing a causal relationship is challenging [160,[166][167][168][169][170][171]. Infants born to mothers who were severely sick with H1N1 influenza infection have been shown to have an increased risk of preterm birth, decreased 5 min Apgar scores, and an increased risk of death [172][173][174]. These data support vaccinating pregnant women to help improve the health of both the mother and child.…”