Hertog’s earlier study of never-married single mothers in Japan that provides an in-depth analysis of Japanese women’s decision-making on childbearing issues and the related value systems was published as a book by Stanford University Press titled Tough Choices: Bearing an Illegitimate Child in Contemporary Japan. Her other research includes analyses of gender differences in time use in East Asia and an investigation of digital dating records from one of Japan’s largest matchmakers to scrutinise partner search processes, identifying the social factors that drive individual success and failure on the Japanese marriage market. She has published in journals such as Journal of Marriage and Family, Demographic Research, and PLOS One.