By Neus Ferrando Gilabert BSc, MSc (embryologist).
Last Update: 04/25/2014

There are several risk factors of OHSS. We mention them hereafter:


OHSS frequency is higher among young women, since they may have a larger number of ovarian follicles and greater density of gonadotropin receptors. It is estimated that the age from which its risk diminishes is 35 years old.

Body Mass Index (BMI)

This syndrome is more frequent among women presenting a low body mass index, that is to say, underweight women.


The frequency of the ovarian hyperstimulation syndrome is higher among pregnant women. In addition, it is further higher in cases of multiple births.

Ovarian Stimulation Protocols

There is much controversy regarding which medicines cause OHSS. Nonetheless, it appears that FSH administration diminishes the risk of OHSS, while the dispensation of GnRh analogs increases it.

Ovarian hyperstimulation syndrome

Follicular response

Estradiol (E2) levels as well as the total number of follicles and their size should be taken into account. Small (less than 9 millimetres) and medium-sized (between 9 and 14 mm) follicles have an increased risk of developing OHSS.

Previous history of OHSS

There is risk of recurrence in cases where previous history of OHSS has occurred. However, it may depend on each patient’s medical history. Together with the rest of risk factors, each woman presents a very particular situation which we cannot generalize or apply to other patients suffering from the same problem.

Polycystic ovary syndrome

The polycystic ovary syndrome (PCOS) (a.k.a. Stein-Leventhal syndrome) is an endocrine disorder causing one of the most frequent hormone imbalances among women of childbearing age. The ovarian hyperstimulation syndrome is more likely to develop where there is polycystic ovary syndrome.

Authors and contributors

 Neus Ferrando Gilabert
BSc, MSc
Bachelor's Degree in Biology from the University of Valencia (UV). Postgraduate Course in Biotechnology of Human Assisted Reproduction from the Miguel Hernández University of Elche (UMH). Experience managing Embryology and Andrology Labs at Centro Médico Manzanera (Logroño, Spain). More information

One comment

    1. Sandra Bynum

      In 1967 at age of 25 I was diagnosed with Stein-Leventhal Syndrome. I had surgery that involved taking a wedge out of each ovary. two years later I delivered a baby boy, and four years after that a baby girl. I have had doctors to snicker when I mention having them wedged, but I am proof it can be successful!!