Ovarian Hyperstimulation Syndrome (OHSS)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 14, 2026

Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic complication of ovarian stimulation protocols used in ART, in which pharmacologically elevated gonadotropin levels cause the ovaries to produce an excessive number of follicles, triggering systemic vascular and fluid changes that range in severity from mild bloating to life-threatening thromboembolism.¹ Mild OHSS is common. Severe OHSS requires hospitalization and can involve ascites, pleural effusion, hemoconcentration, and renal impairment. The condition is classified by grade, and major professional society guidelines address its prevention and management.²

Women with PCOS face the highest OHSS risk because their ovaries contain large numbers of antral follicles that respond aggressively to exogenous stimulation. The antral follicle count that defines PCOS ovarian morphology is the same feature that predicts exaggerated response to gonadotropins. OHSS risk should be part of any informed consent discussion for women with PCOS who are offered ART. Both partners need accurate risk information before proceeding.

OHSS does not occur in restorative reproductive medicine protocols. NaProTechnology, NeoFertility, and related restorative approaches use low-dose hormonal support calibrated to documented cycle deficiencies, not pharmacologic superstimulation. The goal is to support the cycle the patient already has, not to replace it with an artificially driven one. This is a structural difference in the treatment paradigm, not a difference in medication class.

For women with PCOS and anovulatory cycles, the more fundamental question is whether the hormonal and metabolic contributors to anovulation have been identified and addressed before stimulation for ART is considered. Cycle-charting data, including sonographic ovulation classification and hormonal profiling from follicle maturation monitoring, can document ovulatory function precisely. Many women with PCOS who receive targeted metabolic and hormonal support achieve natural conception without the stimulation pathway that carries OHSS risk.

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.