Ovarian hyperstimulation syndrome (OHSS) is almost always presents either after human chorionic gonadotropin (hCG) administration or during early pregnancy. Various inflammatory cytokines (a broad and loose category of small proteins that are important in cell signaling), including vascular endothelial growth factor, have been implicated in the pathophysiology of several late pregnancy complications, including preterm labor, pregnancy induced hypertension or preeclampsia (a disorder of pregnancy characterized by high blood pressure and a large amount of protein in the urine) and intra-uterine growth restriction (poor growth of a fetus while in the mother's womb during pregnancy). Since OHSS was also related to a massive increase in systemic inflammatory cytokines that induces a systemic inflammatory response, a common cause/mechanism may attribute to both severe OHSS with vascular hyper-permeability and the aforementioned pregnancy complications.
Future fertility can be threatened in cases of severe complications such as ovarian torsion or ovarian rupture. In cases when the ovary is necrotic (the premature death of cells in living tissue) due to cessation of blood supply, this ovary needs to be removed.
In very rare occasions, this complication is billateral (on both sides). This leads to infertility and women needs to undergo an egg donation.