Whooping cough, caused by Bordetella pertussis (Bp), is a highly contagious bacterial disease involving the respiratory tract. Despite improvement of vaccination coverage, pertussis remains a major cause of reported childhood morbidity and mortality from a vaccinepreventable disease [1]. Since approximately 1996 the incidence increased worldwide and remained higher than before, despite the change to an acellular vaccine in the vaccination program [1-3].

Postulated causes for the increased incidence are an improved surveillance of the disease, an increasing number of immigrants and bacterial evolution. The waning of naturally derived and vaccine induced immunity in older children and adults is as well a suggested determinant, resulting in increased susceptibility [1,2,4].

Mooi and de Greeff suggested that maternal vaccination against Bp may reduce the related morbidity and mortality of infants [2]. Newborns or partially vaccinated infants, prior to the completion of their primary series of vaccinations, are especially susceptible. Vaccinating pregnant women would result in immunization and protection of the unborn child against whooping cough from birth until the primary vaccination program starts. Ultimately, morbidity and mortality rates of young infants will decrease [5-7]. During the development of a vaccination trial against pertussis in pregnant women an evaluation of the attitude of women towards vaccination in pregnancy was held in order to evaluate whether such a trial would be acceptable to pregnant women.

From January 2008 to July 2008 a total of 300 questionnaires were distributed at the outpatient clinic of the obstetric department of the Groene Hart Ziekenhuis, a general teaching hospital in Gouda the Netherlands. All pregnant women visiting the outpatient clinic were included and were asked to answer a Dutch written questionnaire.

The following items were included (Figure 1):

Figure 1: Questionnaire.

1. Demographics (age, gestational age of current pregnancy, parity and religion),

a. Attitude towards maternal vaccination in general,

b. Attitude towards maternal vaccination against Bp after patient information was given about pertussis and the vaccination.

2. The women with a positive attitude towards maternal vaccination against Bp were requested to answer some additional questions:

c. Attitude towards maternal vaccination if the efficacy and safety of the vaccine is not entirely clear;

d. Attitude towards participation in a clinical trial regarding maternal vaccination.

Women who refused answering the questionnaire and nonrespondents were not further pursued.

Statistical analyses

The frequencies of each response were analyzed. Descriptive analysis of the study variables including demographics were performed using Chi-square testing. A p-value of 0.05 or less was considered significant.

In Figure 2, the results of the survey are shown. A total of 300 questionnaires were distributed, 132 were returned (response rate 44%) and 126 questionnaires were suitable for analysis (42%). Six questionnaires were answered incompletely and therefore excluded.

Before any patient information was given, 95 pregnant women (75%) would approve maternal vaccination against a disease that could be harmful to the newborn (Figure 2a). Arguments for a negative attitude towards vaccination amongst the remaining women (N=31, 24.6%) were fear of harm to the foetus (N= 22, 71.0%), religious reasons (N=2, 6.4%), insufficient information and the preference to discuss this matter with their partner before deciding (N=7, 23%).

Figure 2: Flow diagram of the survey and participants’ response rates.

In Table 1 the demographics of the participants are presented. The mean age of the participants was 32 years; the mean gestational age of pregnancy was 25 weeks. There were no differences in demographics between women who had a negative attitude compared to women with a positive attitude towards maternal vaccination (Table 1). No significant differences were found regarding parity (p=0.26) or religion (p=0.27) of the pregnant women with a positive attitude towards maternal vaccination after reading the patient information.

Table 1: Demographic factors of the pregnant women that participated in the questionnaire survey Binary logistic regression were performed and chi square testing was used.

After reading the provided patient information, 99 of the 126 (79%) woman would consent to maternal vaccination against Bp (Figure 2b). Patient information did not significantly influence attitude towards maternal vaccination (p=0.45). The reasons for a negative attitude were not different after reading the patient information compared to before reading.

When given information that efficacy and safety of the vaccine is not entirely clear, the majority 79 of the 94 women (84%), changed their formerly positive attitude towards maternal vaccination to a negative one (p=<0.05) (Figure 2c).

Of the 55 participants that answered the question about the attitude towards participation in a clinical trial for Bp vaccination, 25 women would agree to participate (45%) (Figure 2d). However 39 women avoided making a clear response to the question.

We studied the importance of patient information regarding Bp vaccination in pregnancy and the influence of this information on agreeing to be vaccinated in order to protect their unborn baby against Bp.

In general it is plausible that pregnant women agree to something that promotes the health of their children. But when we asked the women if they wanted to be vaccinated against a disease that could be harmful to the newborn, three quarters did agree to vaccination before receiving any information about the disease and the vaccination. A reason for this high percentage may be fear of getting the disease and the consequences of the disease for the newborn. The women with a negative attitude in particular wanted more information about the disease and the vaccination before deciding.

In 2010 much commotion occurred concerning the H1N1 influenza epidemic. Worldwide people were massively vaccinated. Little was known about the safety and the efficacy of the vaccine. The disease might have fatal consequences for elderly, children, sick people and pregnant women. Consequently many pregnant women agreed to vaccination.

In a recent study about acceptance of the H1N1 vaccine by pregnant women, Tucker et al. found that willingness to receive the H1N1 vaccine was more related to a higher risk perception about the probability of getting H1N1 and the susceptibility to H1N1 influenza then to distrust of the health care system. They also found that worry about acquiring the disease was a stronger predictor of willingness to be vaccinated, than risk perceptions, distrust, or worry about vaccine safety [8]. Some other researchers found that pregnant women or parents do not necessarily base their acceptance of a vaccine upon a rational process of weighing risks, or upon scientific evidence [9,10]. These facts may be an explanation why there was no significant difference in our study between the attitudes of the pregnant women towards maternal vaccination against Bp before and after patient information was provided.

After patient information was given, there were a few more pregnant women who would agree to maternal vaccination, which implies that patient information possibly can positively influence decisions.

Cheng et al. showed in a cross sectional survey that women who had discussed the postpartum Bp vaccination with their clinicians or who were educated about Bp were more likely to receive vaccination than those who had not [11]. Some other studies reported that pregnant women whose healthcare providers recommended influenza vaccine during pregnancy were more likely to be vaccinated than women who did not receive such suggestions [12,13]. Patient information therefore may be very useful to help people deciding but the result depends on how and by whom it is given.

As we found in our survey, when confronted straightforwardly with uncertainty about safety and efficacy, most pregnant women changed their positive attitude into a negative one. Only 15% of the women would still agree to maternal vaccination against Bp. This is a clear difference, compared to the response of pregnant women towards maternal vaccination after reading the patient information from our study, in which information about the disease, but no assurance on safety and efficacy of the vaccine was given.

Daly et al. and Black et al. reported that women would accept maternal vaccination provided there is strong evidence of its safety and it is widely used. These studies encountered great difficulty recruiting pregnant women into a vaccine trial. The percentage of pregnant women who agreed with maternal vaccination in these studies was between 7.5-19% [14,15].

In our study almost half of the women would like to participate in a trial involving maternal vaccination against Bp. The difference between our results and the results of other studies may be explained by the fact that in our study we only asked if they would consider participating in the program.

Nowadays recommendations in among others the USA, Great- Britain and the Netherlands advocate maternal vaccination against Bp at the beginning of the third trimester [16-20].

The pregnant woman should be informed about data on the safety and efficacy of pertussis vaccination in pregnancy from older and recent studies [21-24].

Several limitations of the study should be addressed:

Firstly, the study was conducted in a single medical centre in the Netherlands, making it difficult to generalize the results.

Secondly, our findings should be considered in the light of their general applicability and validity. Respondents were mostly Caucasian and Dutch speaking and the sample size was small. Religious background was shown not to cause any significant difference in the decision whether or not to be vaccinated (p=0.27), so we may expect no major bias from the ethnical background. Validity of the results may be affected by response bias as 66% of questionnaires were not returned and some respondents purposefully or inadvertently skipped some of the questions. We also have no information about the nonrespondents.

Thirdly, we used a cross sectional study design. Such design precludes determination of causal relationships between various ongoing factors and study outcomes.

Despite the study limitations we conclude that pregnant women are willing to cooperate in vaccination against pertussis in pregnancy when they are given sufficient information about the protection of their child and safety issues. This information might be important for health authorities to consider more research on maternal vaccination against pertussis in pregnancy and the introduction, promotion and delivery of such a vaccine for the protection of the young infant after birth.

The authors wish to thank mw. R.I. Smilde for her support.