a 31% chance of achieving live birth with the use of hCG, the chance of a live birth with the use of an GnRH agonist would be between 12% and 24%. Likewise, using GnRH agonist instead of hCG was associated with a lower ongoing pregnancy rate (pregnancy beyond 12 weeks) than was seen with HCG (odds ratio 0.70) and a higher rate of early (less than 12 weeks) miscarriage (odds ratio 1.74). However, a higher pregnancy rate when using hCG is only found in those receiving luteal support without luteinizing hormone activity (such as progesterone or progestin). Final maturation induction using a GnRH agonist is recommended in women with cancer undergoing fertility preservation, because ovarian hyperstimulation syndrome is associated with an increased risk of arterial thrombotic events such as stroke, myocardial infarction and peripheral arterial embolism, and this risk can add to an already increased risk caused by the cancer. Using hCG versus GnRH agonist has no effect on the risk of multiple pregnancy. Also, no difference has been found between the regimens regarding live birth rate or ongoing pregnancy rate when the controlled ovarian hyperstimulation was followed by oocyte donation. References Fertility Female genital procedures Fertility medicine Obstetrics Human pregnancy Reproduction