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IVF hCG Trigger

The hCG trigger injection is one of the most critical parts of the IVF medication protocol. After the eggs have been stimulated to grow and develop, the hCG trigger is the final medication given before the egg retrieval.

The hCG trigger has several functions:

  • Induce final maturation of the eggs
  • Cause the resumption of meiosis
  • Loosen the egg’s attachment from the follicle wall
  • Allow for the timing of the egg retrieval

If an egg retrieval was not performed, or if it was not performed on time, the hCG trigger would eventually cause ovulation to occur. Therefore, the egg retrieval is performed at a very specific time. At IVF, we like to perform the retrieval as close as possible to 36 hours after the hCG trigger is given.

The levels of hCG that get into the bloodstream are affected by the dose of hCG given and the weight or body mass of the woman taking it. Heavier women have lower hCG levels than lighter women even if they take the same dose. For this reason, we alter the dose of the hCG trigger based on the body mass index of the woman.

hCG is available as two different types of medication:

  • Urinary hCG – Is derived from the urine of pregnant women. Brand names include Pregnyl, Profasi, Novaryl or generic “chorionic gonadotropins for injection”
  • Recombinant hCG – Is produced using recombinant DNA technology. The only brand available is called Ovidrel
Dose of hCG trigger
Women with a BMI of
   Dose of urinary hCG
      Dose of Ovidrel
<30 10,000 I.U.    375 ug (1.5 shots)
30-35 15,000 I.U. 750 ug (3 shots)
>35 20,000 I.U. 1000 ug (4 shots)

See the medication instructions page for how to mix and administer the hCG trigger.