BackgroundTo clarify the frequency, co-occurrence of relationships, and characteristic words of socially high-risk pregnant women who contacted the night telephone triage for advice on pregnancy.MethodsWe performed a quantitative study involving 5,548 of 13,496 pregnancy cases recorded by telephone triage. The contents of telephone triage conversations were examined to determine whether they fulfilled the requirements for each category of socially high-risk pregnant women. The frequency, co-occurrence of relationships, and characteristic words of each category ofsocially high-risk pregnant women were analyzed.ResultsThere were 432 socially high-risk pregnant women. Among 15 categories of socially high-risk pregnant women, young pregnant women (183 cases), mental illness (88 cases), and no antenatal care (80 cases) were the top three categories. There was a strong co-occurring relationship between the following categories of socially high-risk pregnant women: out of touch and lack of supporters; no antenatal care and money matters; out of touch and unmarried; no antenatal care and no issue; money matters and lack of supporters; no issue and lack of supporters; and money matters and unmarried. In characteristic words, some words did not overlap with the top 10 words in other categories.ConclusionsA telephone triage that allows pregnant women to freely talk about their concerns with a coordinator might be useful for detecting socially high-risk pregnant women. To efficiently identify socially high-risk pregnant women, it might be necessary to understand the characteristic words of each category and subsequently determine if the client fulfills the criteria for more than one category of socially high-risk pregnant women.