The purpose of this study is to assess the factors which have influenced the evolution of fertility in Quebec between 1960 and 1990, in order to have a better focus on short and middle term fertility's determining factors. A Whittaker-Henderson filter is applied to various variables presumably linked to the total fertility index in order to retrieve and isolate the trend, which then enables concentration on residuals' co-variations. A regression analysis then enables assessment of the factors' weights and the short term's influence (business cycle). Governmental incentives, notably between 1988 and 1990, appear as having contributed, as well as the overall economic conjuncture, to the observed total fertility index raise in the course of this period.