The purpose of this study is to determine whether cabergoline is effective in reducing the incidence and severity of Ovarian Hyperstimulation Syndrome (OHSS), especially for severe cases; and to derive biomarkers for the risk of developing OHSS.

Severe ovarian hyperstimulation syndrome (OHSS) occurs in up to 2% of in-vitro fertilisation (IVF) cycles, resulting in accumulation of fluid in peritoneal, pleural and pericardial cavities, haemo-concentration with resultant venous thromboembolic phenomena, reduced perfusion of vital organs, renal failure, acute respiratory failure, and even death.

The long term aim is to develop a comprehensive strategy in reducing the incidence and severity of OHSS in in-vitro fertilisation (IVF) cycles. Our short term aim (2-3 years) is to test the ability of the dopamine receptor agonist cabergoline in reducing the incidence and severity of OHSS in high risk women undergoing controlled ovarian hyperstimulation (COH) in fresh IVF cycles through a reduction in vasoactive cytokine levels, specifically in serum vascular-endothelial growth factor (VEGF).

Specifically we will:

1. Conduct a randomised double-blind placebo-controlled trial in women at high risk of developing OHSS during a fresh COH-IVF cycle
2. Investigate the serum and follicular fluid levels for potential biomarkers of OHSS.

Inclusion Criteria:

• Patients with more than 20 oocytes collected after COH in both gonadotropin-releasing hormone (GnRH) agonist and antagonist cycles

Exclusion Criteria:

• Patients with allergy to dopamine agonists
• Patients who undergo in-vitro maturation cycles
• Patients where GnRH analogues have been used to trigger oocyte maturation in antagonist cycles