When the birth control pill was introduced at the beginning of the 1960s, it was primarily used to regulate women's menstrual cycles. Medical historians have argued that such a naturalised menstrual cycle did not exist until hormonal products were used to regulate it. Menstrual irregularities had been the go-to indication for hormonal products, long before hormones were specifically produced for contraceptive purposes. This paper traces the concurrent development of the notion of a "natural cycle" and respective marketing strategies to promote Sequilar, the first sequential birth control pill by Schering AG in 1974. Drawing upon archival resources in the Schering AG Archive, Berlin, the paper examines the notion of producing a "natural cycle." The paper utilises internal documents, letters to doctors, brochures, and prescription guidelines. It argues that the intention of producing a "natural cycle" through hormones led to a naturalisation of menstrual cyclicity and rhythm, while also normalising side effects as part of menstruation.