Fertility decline in human history is a complex enigma. Different triggers have been proposed, among others the increased demand for human capital resulting in parents making a quantity–quality (QQ) trade-off. This is the first study that examines the existence of a QQ trade-off and the possible gender bias by analyzing fertility intentions rather than fertility outcomes. We rely on the unified growth theory to understand the QQ trade-off conceptually and a discrete choice experiment conducted among 426 respondents in Ethiopia to analyze fertility intentions empirically. We confirm the existence of a QQ trade-off only when the number of children is less than six and find that intentions are gendered in two ways: (i) boys are preferred over girls, and (ii) men are willing to trade-off more education in return for more children. Results imply that a focus on both stimulating intentions for education, especially girls' education, and on family size intentions is important to accelerate the demographic transition.