What Is OHSS? Ovarian Hyperstimulation Syndrome Explained

During IVF, medication helps your ovaries grow several eggs at once. Sometimes the ovaries respond too strongly. This is called ovarian hyperstimulation syndrome, or OHSS. It's one of the risks of IVF people don't talk about enough.

At a glance

• In OHSS, the ovaries become swollen and painful after fertility medication. Sometimes treatment has to stop.¹
• Mild OHSS is fairly common. It's been estimated to affect aroundone in three stimulated cycles. Moderate and severe OHSS are less common.²
• It's more likely if your ovaries respond very strongly to medication, and in people with PMOS (formerly called PCOS).²
• Clinics can lower the risk, for example by adjusting medication doses, choosing a different "trigger" injection, or freezing all embryos and transferring later.²

When to get help

During or after treatment, contact your fertility clinic as soon as possible if you have pain and bloating in your tummy, are feeling or being sick, or feel faint.

Call emergency services or go to A&E if you have difficulty breathing, pain in your chest or upper back, swelling anywhere in your body, or you're very thirsty and peeing less than usual. Don't drive yourself.¹

OHSS: The IVF Side Effect People Don't Talk About

▶ Watch: Precious shares what OHSS was like for her during their IVF journey.

Sources & Further Reading

[1] NHS. IVF: Possible complications of IVF. Read the NHS IVF page Contains public sector information licensed under the Open Government Licence v3.0. ↩

[2] Palomba S, Costanzi F, Nelson SM, Besharat A, Caserta D, Humaidan P. Beyond the Umbrella: A Systematic Review of the Interventions for the Prevention of and Reduction in the Incidence and Severity of Ovarian Hyperstimulation Syndrome in Patients Who Undergo In Vitro Fertilization Treatments. International Journal of Molecular Sciences, 2023;24(18):14185. doi:10.3390/ijms241814185 Licence: CC BY 3.0. ↩