Ovarian hyperstimulation syndrome

A young couple tries to concieve for a long time. As the effort is unsuccesful, they arrive to The Centre for Assisted Reproduction. After some examinations the doctor recommends IVF. Basic medicament used for ovarial stimulation before the oocyte retrieval is FSH (follicle-stimulating hormone). Which medicament is aditionally given 36 hours before the oocyte retrieval?