Updated by the Progyny Clinical Team — August 2025.
While in vitro fertilization (IVF) is a safe and effective fertility treatment, it can come with some side effects. One of which is a condition called ovarian hyperstimulation syndrome (OHSS). Thanks to modern advances in fertility care, the risk of OHSS has dropped a lot. Still, it’s good to know about it during your IVF journey.
What is Ovarian Hyperstimulation Syndrome?
OHSS happens when the ovaries have an excessive response to the medications used during IVF. These medications are meant to help your body grow multiple follicles — small sacs in the ovaries that hold eggs. However, there are times when the response is stronger than expected.
When that happens, the ovaries make very high levels of hormones, and fluid can leak from the blood vessels into the belly.
With mild to moderate OHSS, symptoms can include bloating or abdominal pain, nausea, vomiting, and diarrhea.
In severe cases, you would see symptoms such as rapid weight gain, trouble breathing, persistent nausea and vomiting, and blood clots. Moderate to severe OHSS is now extremely rare, thanks to newer medication protocols and improved treatment strategies.
A little hyperstimulation is normal
Keep in mind that IVF is designed to stimulate your ovaries. So, some symptoms such as bloating and discomfort are expected after egg retrieval. This is different from true OHSS.
If you’re feeling more than just mild cramping or bloating, you may have mild OHSS. It can make recovery harder, but it’s generally harmless and goes away on its own.
Why OHSS is rare now
There have been many changes in fertility care to make OHSS uncommon.
Antagonist medications
These newer drugs help control ovulation more precisely, giving your reproductive endocrinologist (REI) better control over stimulation.
Lupron trigger
Previously used to prevent ovulation, Lupron is now used to trigger egg maturation. It helps hormone levels drop faster than traditional triggers such as high-dose human chorionic gonadotropin (hCG), so you start to feel better, sooner.
Lower or no hCG trigger
hCG can keep hormone levels high, which can make OHSS worse. Using less hCG, or skipping it, lowers that risk.
Frozen embryo transfers
Before, transferring a fresh embryo right after retrieval could make OHSS symptoms worse, especially if pregnancy occurred. Now, with reliable freezing methods, your REI can freeze all embryos and do the transfer later — once your body has had time to recover.
Because of all these advances, only 0.02% of IVF cycles now result in moderate to severe OHSS, according to the Society for Assisted Reproductive Technology.
Who’s at higher risk?
Some factors can make OHSS more likely, such as:
- Polycystic ovary syndrome
- A baseline ultrasound follicle count greater than 24
- An anti-Müllerian hormone level greater than 3.4
- An estrogen level higher than 3,500 picograms per milliliter
- A retrieval of more than 15 eggs
- A history of OHSS
How OHSS can be prevented
If your REI sees that you’re at risk for OHSS, they may adjust your treatment plan. They may try:
- Lowering or pausing your stimulation medications.
- Using a Lupron-only trigger shot.
- Starting a medication like cabergoline or bromocriptine after your trigger.
- Choosing to freeze all embryos and delay transfer until a future cycle.
- Giving you letrozole or other medications after retrieval — these are still being studied but may help
What you can expect after retrieval
Feeling bloated is very normal after egg retrieval, even if you don’t have OHSS. Here are a few things to keep in mind as you recover:
- Your ovaries stay enlarged until your next period, which usually comes about 10 to 14 days after retrieval.
- During this time, it’s best to limit activity and drink electrolyte-rich fluids such as coconut water, sports drinks, or broth.
- If you have risk factors for OHSS, try to stay local for at least a week after your retrieval, in case you start feeling worse.
- You don’t need to check your weight or labs unless directed by your REI — just pay attention to how you’re feeling.
If you’re ever unsure whether your symptoms are normal, it’s always okay to reach out to your fertility care team. They’re there to help.
Progyny is here for you, too. Please contact your Progyny Care Advocate for support.
Disclaimer: The information provided by Progyny is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider for medical guidance.