Many studies report empirical relationship either between fertility and labour supply or, between health and labour market outcomes. In this paper, an extension of these ideas involves explicitly considering how fertility and health affect each other, and how they interrelate with labour force participation. A unifying framework is provided and a simultaneous three equations model developed to capture the interdependence between these variables as well as their respective determinants. The model is estimated using a cross-section data set obtained from a survey of the urban Cameroon population. The results indicate that: (i) fertility and health status are significantly interrelated, thus separate estimations of fertility (or health status) and participation will produce misleading results; (ii) working in either sector of the labour market significantly reduces fertility but, unlike many previous studies, fertility has a positive impact on the probability of labour force participation; (iii) there is strong evidence that health and disability status is a significant determinant of employment, but the reverse depend on the labour market sector and on the health indicator used.