A search function of web version 4 of Japan Medical Abstracts Society was used for searching original articles and reports published in Japan from 1983 to 2011. As the result, 48 documents of articles and reports relating to “unbooked delivery” were hit and all of the literatures were obtained through libraries and the like. Reported years, occupations of authors and contents of the 48 literatures were classified and summarized. 【Results&Discussion】Firstly, they were unaffordable for medical expenses due to economic difficulties. Secondly, they were careless about health to the extent being unable to notice their own pregnancy with lack of medical knowledge. Finally, they had lower basis of value against significance of consultation behavior since their previous pregnancy was resulted in easy delivery which made them excuse that checkup was thought to be unnecessary for the second time, that they neglected checkups in spite of recognition of pregnancy and that they were busy.