Access to Ovulation Tests and Strategic Timing of Intercourse in a Low Fertility Context

This is the first study to investigate the impact of increased access to ovulation tests in “lowest-low” fertility populations. We use data from a randomized controlled trial involving 657 heterosexual married women in Singapore, one of the world’s lowest fertility countries. Half of the participants were randomly selected to receive ovulation test kits, which provided personalized information on the timing of their fertile window. 97.72% of participants completed online diaries recording dates of intercourse, menstrual cycles and test results over the next 14 weeks. Random effects regression model results provide evidence that married couples who have not yet achieved their fertility ideals at the time of intervention respond by being significantly more likely to have sex on days with positive test results. Moreover, they only do so on the exact day of positive test results, not on the day before or after. Increasing public access to ovulation tests may allow couples to more accurately time intercourse within the fertile window, potentially helping couples in lowest-low fertility settings to achieve their fertility ideals. However, when wives’ and husbands’ fertility ideals are perceived to be non-aligned, wives strategically use the information to maximize the likelihood of realizing their own ideals. Given the importance of both parents in childbearing, policymakers should carefully consider the implications of such interventions.