Influenza Vaccination in Pregnancy

By Rebecca H. Allen, MD, MPH, Assistant Professor, Department of Obstetrics and Gynecology, Warren Alpert Medical School of Brown University, Women and Infants Hospital, Providence, RI. Dr. Allen reports no financial relationships relevant to this field of study.

Synopsis: In this randomized, controlled trial, text messages regarding the importance of influenza vaccination in pregnancy did not increase vaccine uptake in a low-income population receiving prenatal care.

Source: Moniz MH, et al. Improving influenza vaccination rates in pregnancy through text messaging: A randomized controlled trial. Obstet Gynecol 2013;121:734-740.

The authors performed a randomized, controlled trial at the Magee Women’s Hospital outpatient clinic in Pittsburgh, Pennsylvania, over two consecutive influenza seasons (2010-2011 and 2011-2012). Participants were randomized to one of two text messaging groups: 1) a control group that received information regarding general preventive health in pregnancy and 2) an intervention group that received information regarding general preventive health and the importance of influenza vaccination in pregnancy. The participants received 12 weekly text messages, and inclusion criteria were age 15-40 years, English-speaking, less than 28 weeks pregnant, and possession of a personal cell phone with text-messaging capability. Women were excluded if they had already received the influenza vaccine that season, desired vaccination on the day of enrollment, had been a previous participant in the study, or had contraindications to the vaccine. Both groups received routine prenatal care and there was no cost to receive vaccines in the clinic. The participants completed anonymous surveys before and after the intervention to evaluate beliefs, attitudes, and behaviors toward preventive health care and text messaging. The study was powered to detect an increase in influenza uptake in the intervention arm from an anticipated background rate of 45-70%.

The authors enrolled 204 women out of 2100 women who visited the clinic for prenatal appointments. The intention-to-treat analysis examined 100 women in the control group and 104 women in the intervention group. Of these, 18 women in the control group and 28 in the flu group were considered unevaluable due to pregnancy termination, failure to receive text messaging, or loss to follow up, leaving 82 and 76, respectively, for the per-protocol analysis. The study population was of low socioeconomic status with more than 90% having a high school education or less and 88% utilizing public insurance. The rate of vaccination among study participants was 32% with no difference between the groups (control 31% vs intervention 33%; difference 1.7%; 95% confidence interval -11% to 14.5%). There was no difference between the groups in the per-protocol analysis either. The interval from study enrollment to vaccine administration was no different between the two groups. The overall background influenza immunization rate in the clinic was 37% during the study period. Not surprisingly, vaccinated women were more likely to report that influenza vaccine in pregnancy was somewhat to very important on the baseline survey compared to non-vaccinated women (63% vs 26%, P < 0.001). The text messages made no difference in this initial opinion. Unvaccinated participants reported the following reasons for not choosing to receive the vaccine: They did not like shots (15%), they were afraid of vaccine side effects (23%), and they had a bad experience with the flu vaccine in the past (15%). Despite the lack of effect on vaccination rates, the majority of participants in both groups reported that they liked receiving text messages as part of their prenatal care and found them helpful.


Influenza affects approximately 11% of pregnant women, and pregnant women are more vulnerable to serious morbidity and even mortality compared to the non-pregnant population.1 In addition, influenza infection during pregnancy can cause adverse fetal outcomes. The American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women receive the influenza vaccination yearly regardless of gestational age.2 The vaccine is safe in pregnancy, but it is estimated that only about 50% of pregnant women receive the vaccine.3 This study attempted to evaluate whether text messages focused on the importance of influenza vaccine in pregnancy could increase vaccine uptake among women who initially did not desire the vaccine. The authors conducted the study in a low-income, urban prenatal clinic and did not find any effect from the intervention. Whether these findings are generalizable to other pregnant populations is unknown. Other studies of text messaging attempts to influence health behavior have been mixed. Given the participants’ concerns regarding vaccine safety and fear of needles, the authors acknowledged that more direct text messages addressing these patient-specific barriers to vaccination may have made more of a difference.

Studies have shown that many factors affect whether women choose to receive the influenza vaccine.2,4 The health care provider’s encouragement has been shown to increase vaccine uptake.2,3 Indeed, even in this study, participants stated they would be more likely to receive the vaccine if their health care provider directly recommended it. In addition, ancillary health care workers also have an effect on creating an environment encouraging or discouraging to influenza vaccination.5 Another study published in the same issue of Obstetrics and Gynecology evaluated predictors of influenza vaccination in a pregnant population.4 The authors in this study used the Health Belief Model, which identifies five factors predictive of health behavior change: perceived susceptibility (personal assessment of the risk of getting ill), perceived severity (assessment of the seriousness or consequences of getting ill), perceived barriers (assessment of negative influences related to implementation of the health behavior), perceived benefits (assessment of positive consequences of implementing the health behavior), and cues to action (external influences promoting health behavior). Completely consistent with this model, the authors found that women who perceived they were susceptible to influenza, that they were at risk of getting seriously ill from influenza, and that they would regret not getting vaccinated, and who trusted recommended guidelines about influenza vaccination during pregnancy were more likely to get vaccinated. In contrast, women who were concerned about vaccine side effects were less likely to get vaccinated.

Clearly, we need better strategies to encourage women to obtain the influenza vaccine in pregnancy. A supportive office environment and modeling by health care staff is important.1 Specifically informing patients that pregnant women are at increased risk for influenza and its serious sequelae and reassuring them about the side effects of the vaccine are key.4 In the end, nothing really substitutes for the provider-patient relationship in encouraging vaccine uptake.


1. Fiore AE, et al. Prevention and control of influenza with vaccines: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2010. MMWR Recomm Rep 2010;59:1-62.

2. ACOG Committee Opinion Number 468. Influenza vaccination during pregnancy. October 2010. Obstet Gynecol 2010;116:1006-1007.

3. Centers for Disease Control and Prevention (CDC). Influenza vaccination coverage among pregnant women: 2011-12 influenza season, United States. MMWR Morb Mortal Wkly Rep 2012;61:758-763.

4. Henninger M, et al. Predictors of seasonal influenza vaccination during pregnancy. Obstet Gynecol 2013;121: 741-749.

5. Broughton DE, et al. Obstetric health care workers’ attitudes and beliefs regarding influenza vaccination in pregnancy. Obstet Gynecol 2009;114:981-987.