hCG is a naturally occurring hormone that is produced by the placenta once a pregnancy is established. hCG is the hormone measured in the “pregnancy test”.
Once the eggs within the ovarian follicles mature, the hypothalamus releases GnRH which travels to the pituitary to cause a spike in luteinizing hormone (LH) production. This spike in LH causes ovulation within 36-42 hours. Physiologically, the body responds to a spike in hCG in the same manner as LH thus causing final maturation of the egg and ultimately ovulation (release of the egg). hCG is injected (usually subcutaneously) to induce ovulation in ovarian stimulation cycles for in vitro fertilization (IVF) and intrauterine insemination
(IUI).
hCG is commercially available as Pregnyl, Novarel, Profasi and Ovidrel. Pregnyl, Novarel, and Profasi are “urinary derived human products – uHCG” and Ovidrel are produced using genetic recombinant technology (rHCG). There are no major differences in the clinical effects of these two products. The uHCG is usually less expensive.
Ovidrel is packaged in a prepared syringe and needle making administration easier for patients. Ovidrel usually causes less skin reaction. It is packaged in a 250 mcg dose that is felt to be equivalent to approximately 5,000 – 6,000 IU of uhCG. It is the only FDA approved hCG for subcutaneous use; however the uhCG products have been given subcutaneously for several years with excellent results. Approximately 10% of patients will have a mild skin reaction at the site of hCG injection.
