Oestrogen/Oestradiol: Female sex hormone produced by the ovary. Levels fluctuate during the menstrual cycle.
Oligozoospermia: Low sperm count - less than twenty million sperm per millilitre. It can be severe - less than five million sperm per millilitre.
Oocyte: The female gamete (egg).
Ovarian Hyperstimulation Syndrome (OHSS): A serious complication following stimulation of the ovaries with gonadotrophin drugs.
Ovum: The female gamete (egg).
Page last updated: 18 July 2012