Study	Reason for exclusion
Bancroft 1987	The study examines mood and sexuality.
Christie 1989	The report does not mention how participants were assigned to groups. We attempted without success to reach the author.
Dik 1984	The report does not mention how participants were assigned to groups. We were unable to contact the authors.
Dubnitskaia 1988	Although described as a randomized controlled trial we learned from the author that the study is a matched cohort study.
Grace 1994	Communication with the author indicated no randomization of the allocation sequence.
Kuhl 1985	Insufficient data for analysis of spotting and breakthrough bleeding. Emphasis was on hormonal and metabolic parameters.
Matsumoto 1988	Report does not mention how participants were assigned to groups. We attempted without success to reach the author.
Otolorin 1989	The report describes allocation as systematical. We were unable to contact the author.
Perrone 1987	Report does not mention how participants were assigned to groups. We attempted without success to reach the author.
Rubio‐Lotvin 1992	The report does not mention how participants were assigned to groups. We could not reach the authors.