Human Chorionic Gonadotropin

hCG structure

A hormone typically produced in a pregnant woman's placenta, hCG helps to maintain the corpus luteum, which produces progesterone and estrogen in order to maintain the first trimester of pregnancy. It is taken from the urine of pregnant women and used to induce ovulation in some women.

In assisted reproductive cycles, HCG is injected during ovarian stimulation cycles as the last step prior to either IUI or IVF. If hCG is not injected when the follicles are “ripe”, ovulation may not occur or eggs may not be mature during IUI or IVF, respectively.

This medication induces ovulation 36 hours after its administration in a “properly primed” follicle. Consequently, egg retrieval usually occurs between 34-35 hours after the administration of LH. hCG is usually given when there are mature ovarian follicles (egg sacs) seen on vaginal ultrasound (size >18 to 22 mm) or in conjunction with a positive urine LH surge detection kit. Usually given in a dose of 10,000 units of hCG per vial.

You will be instructed on how and when to give hCG. It is an injectable medication given intramuscular (IM, in the muscle, usually thigh or buttocks). Some fertility specialists also use hCG to support the luteal phase (second half) of a stimulation cycle, because sequential low dose hCG injections will generally stimulate the body to increase its output of progesterone once ovulation has occurred.

Types of hCG

Aside from generic hCG, several brands of hCG are available in the U.S., including:

  • Pregnyl®
  • Novarel™
  • Ovidrel®

Side Effects

The most common side effects include:

  • Headache
  • water retention
  • fatigue
  • sore breasts

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