Chengdiao is interested in demography, evolutionary theories, and studies on women. In her doctoral program, she intends to study the decline of fertility rates in human populations and to ask whether humans have any natural inclination to reproduce. Human fertility decline poses a big evolutionary puzzle. Humans may have natural instincts for sex and are selected to care for their offspring once their children are born, but whether they are inclined to reproduce is still a question. The pre-transitional high fertility rates have been shown to be results of strong pronatalist pressures from needs for wealth, labor, power and various social causes. Once the biological link between sex and reproduction was cut by contraception, and social changes initiated freer reproductive choices of people, fertility declined, to different extents in almost all human populations. Chengdiao’s fieldwork was conducted in Taiwan where fertility rates are among the lowest of the world. She interviewed 227 Taiwanese women, collecting both quantitative and qualitative data intensively on women’s decision-making processes on reproduction, family backgrounds, education, economic income and expenses, occupation, relationships and interactions with husbands, in-laws, relatives and close friends, social networks, women’s views on Chinese traditions about reproduction etc..