Trigger Shots 101

trigger shot

The trigger shot is one of the most exciting shots in the injectable fertility medication lineup because it’s administered when you’re egg follicles are adequately matured. Trigger shots are used in several different scenarios, depending on your family-building plans, reproductive history, or fertility treatment needs.

Whether you’re just embarking on the fertility journey or almost ready to begin the egg retrieval process, we’ve outlined everything you need to know about the trigger shot: what it is, how it works, and its potential side effects.

Introduction to Trigger Shots

Trigger shots are used because ovulation always occurs about 36 hours after the injection. This precise timing allows your fertility physician to time IUI, egg retrieval, or embryo transfer more precisely. Depending on your needs, trigger shots are one of two things: human chorionic gonadotropin (HCG) or a GnRH agonist.

  • HCG: Human chorionic gonadotropin goes by the brand names Pregnyl, Novarel, or Ovidrel. It is very similar in structure to luteinizing hormone (LH), which is the hormone that rises in the middle of your menstrual cycle to induce the final stages of egg (oocyte) maturation and the egg’s release (ovulation).
  • GnRH agonist: GnRH agonist (Lupron) is a newer trigger shot option, although it’s long been used as a hormone therapy for other medical conditions such as endometriosis or estrogen-feeding cancers. It works slightly differently than HCG. Rather than replating LH to create the surge, Lupron stimulates a natural rise of LH hormones, triggering oocyte maturation and release.

Depending on your case, your fertility specialist may recommend one or the other – or they may recommend a combination of the two – the combo shot.

How & When Are Trigger Shots Administered

There’s no reason to worry about the “when” of your trigger shot. Fertility specialists work closely with patients during the fertility medication cycle, and we closely watch the maturing egg follicles. We’ll let you know when to administer the trigger shot and set your egg retrieval appointment accordingly.

A review of a typical IVF timeline applies to any woman using injectable fertility medications for egg retrieval up through the fertilization and transfer steps. You’ll administer your own prescribed trigger shot (your partner can help) just as you have with the others. It is a “one and done” shot. Most women inject it into their abdomen, but you and your physician decide what’s best.

Fertility Shots for Timed Intercourse

Sometimes women use injectable fertility medications to increase their chances of getting pregnant at home via timed intercourse. This route should only be pursued under the guidance of a fertility specialist. Oral fertility medications (Clomid) are the most commonly used for getting pregnant at home because they are milder and are prescribed to ensure that only one or two eggs mature per cycle.

If you have undiagnosed PCOS or the wrong dose of fertility medications, you can wind up releasing a large number of eggs at once. These are the situations that result in “Octomom” pregnancies. You do not want that to happen to you. If you are working with a fertility specialist and using injectable meds to time intercourse, your doctor will probably prescribe a HCG shot.

Risks & Side Effects Associated With Trigger Shots

Each approach has pros and cons, and your physician will discuss those with you to help you make the best choice for your desired outcome. For example, women who use HCG trigger shots have a higher risk of developing hyper ovarian stimulation syndrome (HOSS) but higher live embryo transfer success rates. Women who use GnRH agonist options have lower success rates with live embryo transfers but minimize their risk of HOSS.

Because of this, HCG trigger shots or combo shots may be the best option if you’re pursuing IVF using frozen embryos. Women choosing to bank their eggs for fertility preservation or delayed family building often opt to use GnRH trigger shots. GnRH agonist trigger shots are often the version used for egg donors. And, because of the way GnRH agonists work by halting hormone production in the ovaries, they’re also the first choice for certain patients with cancer as they align well with their current treatment.

Need More Trigger Shot Information?

Do you have more questions about how trigger shots work, side effects, or which one is right for you? Contact us today to schedule a fertility appointment.

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