BACKGROUND: A chart indicating the likelihood of conception linearly declining with age (86% for women aged 20-24, 78% for 25-29, 63% for 30-34, 52% for 35-39, 36% for 40-44, 5% for 45-49, and 0% for 50 and over) is widely used on Internet fertility sites and by medical professionals. Its origin has been unknown until now. OBJECTIVE: To explore the origin of the chart. METHODS: A literature survey. RESULTS: Among the seven points on the curve, three are based on data that are not the likelihood of conception, while four are probably derived from oversimplified description of fecundability estimates for Hutterite and Taiwanese women in the 1950s and 1960s. Two professionals contributed to the making of these data. CONCLUSIONS: The chart was fabricated and exaggerates the effect of age on the likelihood of conception. At least two professionals are responsible for the fabrication. CONTRIBUTION: This paper describes a case of misinformation about demographers' research results. It issues a warning against misuse of demographic knowledge in medical, commercial, educational, and political contexts.