Ovarian Hyperstimulation Syndrome (OHSS)

Ovarian hyperstimulation syndrome is a well-recognised heightened response to hormonal stimulation of the ovaries. Mild to moderate ovarian hyperstimulation syndrome can occur in up to 20% of women, and severe symptoms occur in less than 1%. Your fertility specialist will consider your risk of ovarian hyperstimulation when planning your treatment. During your stimulation, your scan and blood results will be monitored for any indication that you may be at risk of ovarian hyperstimulation. If you are identified as being at risk, your fertility nurse will discuss your results with you, provide advice and support.


Strategies to help prevent Ovarian Hyperstimulation Syndrome

Changing your trigger medication
Trigger medications are administered to prepare your eggs for collection. Some trigger medications contain pregnancy hormone (hCG), which can significantly heighten the severity of ovarian hyperstimulation syndrome. Your fertility specialist may decide to change your trigger medication to negate this risk.

Freezing embryos (if applicable)
You may have planned to have an embryo transfer in your treatment cycle; however, pregnancy hormones produced from implantation of the embryo can heighten the severity of ovarian hyperstimulation syndrome. If your embryo transfer is cancelled, it will be re-scheduled for your next treatment cycle.

Complications of ovarian hyperstimulation syndrome
Ovarian hyperstimulation syndrome is categorised into 3 levels of severity: mild, moderate, and severe.

Some of the complications experienced from ovarian Hyperstimulation Syndrome include:


  • Bloating of the abdomen
  • Abdominal tenderness
  • Rapid weight gain
  • Nausea and vomiting


  • Breathing difficulties
  • Sharp abdominal pain
  • Heat and pain in your limbs

 Some risk factors may include:

  • Polycystic ovarian syndrome (PCOS)
  • High AMH or antral follicle count
  • Age under 30
  • Low BMI
  • Previous episodes of OHSS
What if I have Ovarian Hyperstimulation Syndrome?

If you think you are showing signs of ovarian hyperstimulation syndrome, please call the clinic and ask to speak to a nurse. Your nurse will arrange wellbeing calls and provide you with advice on how to manage your symptoms. You may be asked to come to the clinic for an ultrasound and blood test.

In case of a medical emergency please call 000 or visit an emergency department

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