Ovarian Hyperstimulation Syndrome (OHSS) is a potential complication of fertility  treatments that involve stimulating the ovaries to produce multiple eggs, such as in vitro fertilization (IVF). While most cases are mild and resolve on their own, it’s important for  patients to understand the symptoms, risk factors, and how fertility specialists work to  minimize the risk.  

What is OHSS? 

OHSS occurs when the ovaries respond too strongly to fertility medications used during  controlled ovarian stimulation. This response can cause the ovaries to become enlarged  and lead to fluid shifting from blood vessels into the abdomen or chest. Moderate to severe  OHSS occurs in approximately 1-5% of IVF cycles, although modern protocols have  significantly reduced the risk.  

OHSS can occur in two forms: 

• Early OHSS, which develops within about a week after the trigger injection used to  mature eggs.  
• Late OHSS, which occurs later and is often related to the hormonal changes of early  pregnancy.  

Common Symptoms 

Symptoms vary depending on severity. Mild cases are the most common and may include:  

• Abdominal bloating or discomfort  
• Mild nausea 
• Ovarian enlargement 
• Temporary weight gain  

More severe symptoms can include significant abdominal swelling, shortness of breath,  decreased urination, severe nausea or vomiting, and rapid weight gain. Severe OHSS is  rare but requires prompt medical attention.  

Who is at Higher Risk? 

Certain factors can increase the likelihood of developing OHSS, including:  

• Polycystic ovary syndrome (PCOS) 
• High ovarian reserve markers such as elevated AMH levels  
• A high number of follicles during stimulation
• High estrogen levels during treatment  
• Younger age  

Patients with these characteristics may respond more strongly to fertility medications. To  reduce the risk, fertility specialists closely monitor patients during stimulation and may  adjust medication doses, use protocols with lower OHSS risk, prescribe preventative  medications when appropriate, or recommend freezing embryos for transfer in a later  cycle to avoid immediate pregnancy. These strategies have significantly lowered the risk of  moderate and severe OHSS in modern IVF treatment.  

When to Contact Your Care Team 

Patients undergoing fertility treatment should contact their clinic if they experience:  

• Severe abdominal pain or swelling 
• Rapid weight gain (more than a few pounds in a couple of days) 
• Difficulty breathing  
• Persistent vomiting  
• Reduced urination  

Early communication allows your care team to monitor symptoms and intervene if  necessary. With careful monitoring, individualized treatment plans, and modern  prevention strategies, fertility specialists work to keep patients safe while maximizing the  chances of a successful pregnancy. 

Take the Next Step in Your IVF Journey

If you have questions about cycle priming or your IVF treatment plan, the team at Beverly Hills Fertility is here to help. Our specialists use evidence-based strategies and personalized care to design the most effective approach for your unique needs.

Schedule a consultation today to better understand your treatment plan and take the next step toward building your family with confidence.