Objectives: To assess and quantify the relationship between polycystic ovaries (PCOs) and ovarian hyperstimulation syndrome (OHSS).
Data sources: Published studies, any language, identified through MEDLINE, EMBASE, BIOSIS, Web of Science, and bibliographies. Studies were selected if exposure (ultrasound findings of PCO before treatment) and outcome (OHSS) could be abstracted to two-by-two tables.
Results: Ten studies, meeting inclusion and exclusion criteria, were analyzed. When PCO were present, the combined odds ratio for OHSS was 6.8 (95% confidence interval 4.9-9.6).
Conclusion: There is a significant and consistent relationship between PCO and OHSS. When PCO are present before treatment with assisted reproduction, deliberate policies to moderate treatment appear justified.