A cross sectional study on fertility knowledge in Japan, measured with the Japanese version of Cardiff Fertility Knowledge Scale (CFKS-J)

Background: A recent survey of 79 countries showed that fertility knowledge was lower in Japan than in any other developed country. Given the fertility decline in Japan and the importance of fertility knowledge, we conducted an online survey to examine fertility knowledge and the related factors for effective public education. Methods: We studied people aged 18-59 years old, n = 4,328 (the General group), and also people who had been trying to conceive for at least six months, 18-50 years old, n = 618 (the Triers group). Fertility knowledge was assessed using the Japanese version of the 13-item Cardiff Fertility Knowledge Scale (CFKS-J). All participants provided socio-demographic and fertility information. Participants also completed a 14-item health literacy scale and an 11-item health numeracy scale. We asked participants who were aware of age-related decline in fertility when and where they first acquired that knowledge. Results: The average percentages of CFKS-J items answered correctly were 53.1% in the Triers group and 44.4% in the General group (p < 0.001). Multivariate linear regression models showed in the Triers group greater fertility knowledge was associated with greater health literacy and prior medical consultation regarding their fertility. In the General group greater fertility knowledge was associated with being female, younger, university educated, currently trying to conceive, non-smoking, having higher household income, having higher health literacy and having higher health numeracy. Of those who were aware of the age-related decline in fertility, around 3% first learned the fact at school, and around 65% first learned it through mass media or via the Internet. More than 30% of the respondents first learned it less than 5 years before the survey. Conclusions: Although fertility knowledge had improved since a previous study, possibly due to recent media coverage of age-related infertility, it was still low. Educational interventions, both in schools and in the community, may be needed to increase fertility knowledge in the general population because most people obtain fertility knowledge from mass media, which has been shown to often present distorted and inaccurate fertility information.