Our observational survey regarding knowledge and risk behaviour related to toxoplasmosis, listeriosis and CMV infections during pregnancy showed that - although there was limited knowledge about specific practices to prevent each of these infections - the majority of respondents reported they practiced appropriate behaviour to prevent toxoplasmosis and listeriosis, but not to prevent CMV.
A strength of this study is its large sample size (n = 1,097) and high response rate (66.0%). This study observed both knowledge about preventive practices and the actual risk behaviour of pregnant women regarding preventable infectious diseases, which has not been conducted by many other studies. However, the study population was not representative for all pregnant women in the Netherlands. The study population included mainly higher educated women and women without the Dutch nationality were under-represented [30, 31]. This could be partly due to the fact that the questionnaire was not presented in other languages than Dutch. It is also possible that women who did not know the answers did not return the questionnaire, which may have resulted in an overestimation of knowledge levels. In addition, the behavioural questions may have contributed to social desirability bias, which may have affected the frequency of of reported risk behaviour. Another potential weakness of this study is that only respondents who had children aged less than five years answered the questions about preventive behaviours regarding CMV infections. By doing this we could have missed important information from other respondents who are also at risk for CMV infections, like women who work in a children-day care setting or other health care setting. It needs also to be mentioned that we considered risk behaviour to be present if a respondent reported one of the included risk behaviours at least once during their current pregnancy. This may indicate that the many respondents who had undertaken a risk behaviour were actually not frequent risk takers, but had a single exposure. In addition, as this study had a cross-sectional design, the interpretation of associations should remain with caution.
This study indicates that health care professionals play an important role in informing women about preventable infectious diseases as many respondents reported having received information about toxoplasmosis, listeriosis or CMV from their health care provider. Books, magazines and the Internet were also important sources of information for the respondents. Most pregnant women in the Netherlands receive a brochure entitled “Pregnant” during their first antenatal care visit, which is developed by several Dutch organizations involved in mother and child care. This brochure includes information on listeria and toxoplasmosis, but not on CMV infections, which could partly explain the general lack of knowledge of the respondents about CMV. Confirmed by other studies, this study revealed lower median knowledge scores for preventive practices for toxoplasmosis among respondents who had less formal education, had an unplanned pregnancy, were single, had smoked during pregnancy and had never worked as a health care professional. For listeriosis lower level of median knowledge score were seen among respondents who were younger than 25 years, had less formal education, had an unplanned pregnancy, were single, experienced their first pregnancy, had smoked during pregnancy and had never worked as a health care professional [5, 7, 10]. In addition to these two infectious diseases, this study revealed that respondents with the Dutch nationality and respondents who spoke Dutch at home, had less knowledge about CMV preventive practices. Women with a non-Dutch nationality may have had more knowledge, and thus be more aware, of CMV infections, because the maternal and congenital CMV prevalence is higher among immigrants than among native mothers [22, 32]. Counter to our hypothesis and confirmed by another study , disease specific knowledge was not necessarily associated with preventive behaviour during pregnancy, regarding toxoplasmosis and listeriosis. And conversely, a lack of knowledge was not always associated with engaging in risk behaviour. Infection with toxoplasmosis during pregnancy is highly associated with eating raw or undercooked meat . And while only half of the respondents demonstrated knowledge of this relationship, the majority indicated that they avoided the behaviour. These results are comparable with alcohol consumption during pregnancy. Many women know they should not drink alcohol during pregnancy, but they do not exactly know the effects of alcohol on the foetus . Contrarily, although there was an overall good understanding that toxoplasmosis could be prevented by gardening with gloves, only one fifth of the respondents did garden without gloves during their pregnancy. For six out of the eight included risk behaviours, there were almost no differences in reported risk behaviours between respondents who were or were not aware of the practices to prevent infectious diseases.
Respondents with a higher educational level, who had the Dutch nationality, who did not take folic acid in their first trimester or ever worked in a children day-care setting had greater odds to report a risk behaviour for toxoplasmosis. Respondents who were in their third phase of pregnancy had higher odds to report a risk behaviour for listeriosis, but lower odds to report a risk behaviour for CMV. These factors indicate that health care professionals involved in mother and child care should give more attention to these women with regard to infectious disease prevention. Behaviour change depends on a range of factors, including the perceptions of the threat . It is possible that women with a higher education are more aware of the low risk of contracting an infectious disease during pregnancy. Pregnant women receive large amounts of information during their first prenatal visit, including methods to prevent infectious diseases and as the amount of information increases, cognitive shortcuts could arise. This may imply that it is more effective for health care professionals to inform pregnant women briefly about behaviours and lifestyle habits they should adopt or avoid and that it may not be necessary to give information on specific infectious diseases. In addition, it could be helpful to repeat some information on preventive practices during a later stage in pregnancy, than only during one of the first prenatal visits. Some preventive methods need more emphasis in prenatal health care, because these were not well adopted by pregnant women in this current study. These preventive methods concern hygienic behaviours in general (e.g. not sharing utensils or cups with children and hand washing after diaper change) to prevent CMV infection, washing or peeling raw fruits and vegetables to prevent toxoplasmosis and properly reheating ready to eat foods to prevent listeriosis.
Concerning CMV, respondents who had less knowledge about the preventive practices did not report more often risk behaviour than respondents with knowledge about the preventive practices. There was a general lack of knowledge, illustrated by the fact that only one eighth of the respondents had ever read, seen or heard anything about CMV and the majority of respondents did not adopt methods to prevent CMV infections. Women within certain professions such as children-day-care workers have a 5 to 25 fold higher risk of acquiring a primo CMV infection during their pregnancy compared to women not in contact with young children [35, 36]. However, this study did not find differences in behaviour between respondents who ever worked in a health care or in a children day-care setting and respondents who did not. An explanation for the general lack of knowledge and lack of adopting behaviours towards CMV infection prevention is that health care workers pay little attention to CMV infection [21, 27, 35]. Another study showed that Dutch doctors involved in mother and child care had suboptimal knowledge on CMV themselves, and they seemed to underestimate the prior risk for a child with congenital CMV infection in their practice . However, it may be important for health care professionals to give information on CMV prevention to pregnant women in the future as a study in France showed that simple information on basic hygiene measures given to women at the beginning of their pregnancy could significantly reduce the incidence of maternal infection during pregnancy [36, 37]. In addition, a recent study showed a congenital CMV birth prevalence rate of 0.54% in the Netherlands , which is higher than the birth prevalence rate of 0.09%  showed in an earlier study and on which many Dutch professional educational materials and guidelines are based .
Pregnant women seemed to appropriately avoid risk behaviour without exactly knowing why they avoid it. This could reflect the use of cognitive shortcuts, where complex tasks are reduced to simpler operations which allows people to make rapid, efficient, but sometimes irrational choices [38, 39].
Some studies suggest that written education is less effective to establish behavioural change than when health care providers inform clients orally about correct behaviour [40–42]. However, this study did not find any difference in the occurrence of risk behaviour between those we received information on the infectious disease from their health care professional and those who received information through other sources. It would be interesting to investigate what kind of information health care professionals involved in mother and child care give orally and what kind of information they give in written materials about preventable infectious diseases.