Professional Responsibility for Spreading Unscientific Knowledge

- the case of the 'ease of conception' graph in a supplementary high school textbook
TANAKA Sigeto <>
(Graduate School of Arts and Letters, Tohoku University)
Translation from an author manuscript for Trends in the Sciences 22(8):18-23 (2017-09-03)

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The government of Japan and professionals from the fields of obstetrics, gynecology, and reproductive medicine used a graph exaggerating the decline in women's fecundity, professing it begins a sharp linear descent in their mid-20s. It was used in a campaign to promote "accurate" knowledge about the suitable age range for pregnancy and was published in a supplementary textbook of health education for high schools in 2015. The author criticizes the use of the graph as well as the use of other unreliable research findings in the campaign that has resulted in the spread of unscientific knowledge in Japan today.

Table of contents

  1. The high school supplementary textbook scandal in 2015 Japan
  2. The data sources of the "ease of conception" graph and their problems
  3. An international comparison of fertility literacy: The impact of IFDMS
  4. Professional responsibility


Figure 1: "Life plan" illustration in the supplementary textbook (note that this is intended only for females)

文部科学省『健康な生活を送るために』(2015年度版) p. 38.


Figure 2: The graph indicating a woman's "ease of conception" and how it changes with age (the version that appeared in the textbook, as of August 2015)

文部科学省『健康な生活を送るために』(2015年度版) p. 40.


Figure 3: ASMFR for Hutterite women, classified by age at marriage

Three-year moving averages calculated by the author based on Sheps (1965: Table 2). See Tanaka (2007: 141, note v)



[Bendel and Hua 1978] Bendel, Jean-Pierre, and Chang-i Hua, 1978, "An Estimate of the Natural Fecundability Ratio Curve." Social Biology, 25(3): 210-227. {DOI:10.1080/19485565.1978.9988340}
[Boivin et al. 2011] Boivin, Jacky, et al., 2011, "His & Her Biological Clock: Reproductive Decision-making and Reproductive Success in the 21st Century" (ESRC Impact Report, RES-355-25-0038). {}
[Bunting et al. 2013] Bunting, Laura, Ivan Tsibulsky, and Jacky Boivin, 2013, "Fertility Knowledge and Beliefs about Fertility Treatment: Findings from the International Fertility Decision-Making Study," Human Reproduction, 28(2): 385-397. {DOI:10.1093/humrep/des402}
[Irahara 2015] 苛原稔,2015,「理事長コメント:文部科学省高校生用啓発教材「健康な生活を送るために」の中の「20. 健やかな妊娠・出産のために」に関する意見」(日本生殖医学会, 9月7日). {}
[Nishiyama and Tsuge 2017] 西山千恵子・柘植あづみ編,2017,『文科省/高校「妊活」教材の嘘』論創社. {ISBN:9784846016265}
[O'Connor et al. 1998] O'Connor, Kathleen A., Darryl J. Holman, and James W. Wood, 1998, "Declining Fecundity and Ovarian Ageing in Natural Fertility Populations," Maturitas, 30(2): 127-136. {DOI:10.1016/S0378-5122(98)00068-1}
[Sheps 1965] Sheps, Mindel C.,1965, "An Analysis of Reproductive Patterns in an American Isolate," Population Studies, 19(1): 65-80. {DOI:10.1080/00324728.1965.10406005}
[Tanaka 2017] Tanaka Sigeto, 2017, "Works Citing Bendel and Hua on Natural Fecundability: A Literature Review on the Origin of a Falsified Chart Used in High School Education in Japan," 『東北大学文学研究科研究年報』66: 142-128. {}
[Tanaka forthcoming] Tanaka Sigeto, forthcoming, "Another Science War: Fictitious Evidence on Women's Fertility and the 'Egg Aging' Panic in 2010s Japan," Advances in Gender Research, 24. {}
[Wood 1989] Wood, James W., 1989, "Fecundity and Natural Fertility in Humans," Oxford Reviews of Reproductive Biology, 11: 61-109. {}
[Yoshimura 2013] 吉村やすのり,2013,「卵子の老化—続報— 女性の年齢と妊孕力との関係」(2015年8月23日取得) <>

Additional information

The online edition of the textbook is available from Upon each successive revision, the preceding edition is deleted. However, past editions can be found on archive sites such as

I discussed three other graphs in the symposium report ( , on which this paper is based. For more details on those graphs, see Tanaka (forthcoming). This article owes a great deal to the efforts of an activist group, which are reported in Nishiyama and Tsuge (2017). I would like to express my appreciation to all those who contributed valuable information and ideas, including anonymous Twitter account holders. English translation and editing services were offered by Editage (, and covered under the fund from JSPS KAKENHI Grant Number 17K02069.


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