In an analysis of surveillance data from the state of Georgia (US), Saad Omer and colleagues show an association between receipt of influenza vaccination among pregnant women and reduced risk of premature births.

Background

Infections during pregnancy have the potential to adversely impact birth outcomes. We evaluated the association between receipt of inactivated influenza vaccine during pregnancy and prematurity and small for gestational age (SGA) births.

Methods and Findings

We conducted a cohort analysis of surveillance data from the Georgia (United States) Pregnancy Risk Assessment Monitoring System. Among 4,326 live births between 1 June 2004 and 30 September 2006, maternal influenza vaccine information was available for 4,168 (96.3%). The primary intervention evaluated in this study was receipt of influenza vaccine during any trimester of pregnancy. The main outcome measures were prematurity (gestational age at birth <37 wk) and SGA (birth weight <10th percentile for gestational age). Infants who were born during the putative influenza season (1 October–31 May) and whose mothers were vaccinated against influenza during pregnancy were less likely to be premature compared to infants of unvaccinated mothers born in the same period (adjusted odds ratio [OR] = 0.60; 95% CI, 0.38–0.94). The magnitude of association between maternal influenza vaccine receipt and reduced likelihood of prematurity increased during the period of at least local influenza activity (adjusted OR = 0.44; 95% CI, 0.26–0.73) and was greatest during the widespread influenza activity period (adjusted OR = 0.28; 95% CI, 0.11–0.74). Compared with newborns of unvaccinated women, newborns of vaccinated mothers had 69% lower odds of being SGA (adjusted OR = 0.31; 95% CI, 0.13–0.75) during the period of widespread influenza activity. The adjusted and unadjusted ORs were not significant for the pre-influenza activity period.

Conclusions

This study demonstrates an association between immunization with the inactivated influenza vaccine during pregnancy and reduced likelihood of prematurity during local, regional, and widespread influenza activity periods. However, no associations were found for the pre-influenza activity period. Moreover, during the period of widespread influenza activity there was an association between maternal receipt of influenza vaccine and reduced likelihood of SGA birth.

Please see later in the article for the Editors' Summary

Editors' Summary

Background

Maternal infections during pregnancy can have harmful effects on both mother and baby. For example, influenza is associated with increased morbidity and mortality among pregnant women compared to women who are not pregnant or who acquire influenza infection after delivery. And some respiratory infections, especially those that can cause maternal pneumonia such as influenza virus, are known to be associated with the baby being small—below the 10th percentile—for gestational age and with an increased risk of preterm birth—birth before 37 weeks of gestation. Previous studies have shown that inactivated influenza vaccination during pregnancy provides protection against influenza virus for both mother and baby. As there has been an increase in the rate of preterm birth the United States from 9.5% in 1981 to 12.8% in 2006, the impact of maternal influenza immunization on birth outcomes has important public health implications and is of particular interest during influenza pandemics.

Why Was This Study Done?

Given that maternal vaccination can protect babies from influenza virus, it is plausible that influenza vaccination in pregnancy could mitigate adverse birth outcomes such as prematurity and the baby being small for gestational age. The researchers of this study set out to evaluate this hypothesis by investigating whether there was an association between women receiving inactivated influenza vaccine during pregnancy and positive birth outcomes for their babies in the population of the state of Georgia, in the United States.

What Did the Researchers Do and Find?

The researchers conducted a retrospective cohort analysis of a large surveillance dataset (the Georgia Pregnancy Risk Assessment Monitoring System) to analyze the relationship between receipt of inactivated influenza vaccine during any trimester of pregnancy by mothers of infants born between June 1, 2004, and September 30, 2006, and their baby being premature or small for gestational age. The study period encompassed the 2004–2005 and 2005–2006 influenza seasons—the two most recent seasons for which the data were available. The researchers did a stratified analysis for the overall study period, and various periods during it, and also weighted their analysis to adjust for possible oversampling. They used logistic regression to evaluate the association of maternal influenza vaccine and (a) prematurity and (b) small for gestational age, and also used linear regression to evaluate the statistical significance of differences between vaccinated and unvaccinated women for mean gestational age at first antenatal visit and mean birth weight.

During the study period, 4,168 mother–baby pairs were included in the analysis. Local influenza activity was detected during 27 weeks (22.1%), and 578 women (14.9% [weighted]) had received the influenza vaccine during pregnancy, giving a vaccination coverage of 19.2% (weighted) among mothers of infants born during the assumed influenza season. In the study sample, 1,547 babies (10.6% [weighted]) were born premature, and 1,186 babies (11.2% [weighted]) were small for gestational age. Infants who were born during the assumed influenza season (October–May) and whose mothers were vaccinated against influenza during pregnancy were less likely to be premature than infants of unvaccinated mothers born in the same period, with an adjusted odds ratio of 0.60. The effect of maternal influenza vaccine on reducing prematurity was the highest for infants born during the period of widespread influenza activity, with 72% lower odds of prematurity in infants of vaccinated mothers than infants of unvaccinated mothers. Compared with newborns of unvaccinated women, babies of vaccinated mothers also had 69% lower odds of being small for gestational age during the period of widespread influenza activity, but the adjusted and unadjusted odd ratios were not significant for the pre-influenza activity period.

What Do These Findings Mean?

These results show that there was an association between maternal immunization with the inactivated influenza vaccine during pregnancy and reduced likelihood of prematurity during local, regional, and widespread influenza activity periods. In addition, during the period of widespread influenza activity there was an negative association between maternal receipt of influenza vaccine and small for gestational age birth.

Additional Information

Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000441.

More information about influenza vaccination during pregnancy is available from the World Health Organization and the UK National Health Service

More information about the Georgia Pregnancy Risk Assessment Monitoring System is also available

Background:

In Malawi, cervical cancer is the most prevalent form of cancer among women, with an 80% mortality rate. The Mulanje Mission Hospital has offered free cervical cancer screening for eight years; however, patients primarily seek medical help for gynecologic complaints after the disease is inoperable.

Methods:

We investigated how women in rural Malawi make health-seeking decisions regarding cervical cancer screening using qualitative research methods. The study was conducted between May and August of 2009 in Mulanje, Malawi.

Results:

This study found that the primary cue to action for cervical cancer screening was symptoms of cervical cancer. Major barriers to seeking preventative screening included low knowledge levels, low perceived susceptibility and low perceived benefits from the service. Study participants did not view cervical cancer screening as critical health care. Interviews suggested that use of the service could increase if women are recruited while visiting the hospital for a different service.

Conclusion:

This study recommends that health care providers and health educators target aspects of perceived susceptibility among their patients, including knowledge levels and personal risk assessment. We believe that continued support and advertisement of cervical cancer screening programs along with innovative recruitment strategies will increase usage density and decrease unnecessary deaths from cervical cancer in Malawi.

Limited information is available at the national and district levels on causes of death among women of reproductive age in Bangladesh. During 1996–1997, health-service functionaries in facilities providing obstetric and maternal and child-heath services were interviewed on their knowledge of deaths of women aged 10–50 years in the past 12 months. In addition, case reports were abstracted from medical records in facilities with in-patient services. The study covered 4,751 health facilities in Bangladesh. Of 28,998 deaths reported, 13,502 (46.6%) occurred due to medical causes, 8,562 (29.5%) due to pregnancy-related causes, 6,168 (21.3%) due to injuries, and 425 (1.5%) and 259 (0.9%) due to injuries and medical causes during pregnancy respectively. Cardiac problems (11.7%), infectious diseases (11.3%), and system disorders (9.1%) were the major medical causes of deaths. Pregnancy-associated causes included direct maternal deaths (20.1%), abortion (5.1%), and indirect maternal deaths (4.3%). The highest proportion of deaths among women aged 10–19 years was due to injuries (39.3%) with suicides accounting for 21.7%. The largest proportion of direct obstetric deaths occurred among women aged 20–29 years (30.5%). At least one quarter (24.3%) of women (n=28,998) did not receive any treatment prior to death, and 47.8% received treatment either from a registered physician or in a facility. More focus is needed on all causes of deaths among women of reproductive age in Bangladesh.