How Gonadotropin Injections Work in IVF
Quick answer:
Gonadotropin injections are fertility medications used during IVF to stimulate the ovaries to produce multiple eggs in a single cycle. These injectable hormones, which include FSH and LH-based medications, are carefully timed and monitored to improve egg development and increase the chances of IVF success.
Gonadotropin injections can feel intimidating at first, especially for patients new to IVF. While the medication schedule may seem complex, most people find that the process becomes manageable once they understand how the injections work and why they are used.
These medications play a central role in ovarian stimulation, helping your fertility team recruit and mature multiple eggs during a single IVF cycle.
What Are Gonadotropin Injections?
Gonadotropins are injectable hormones that stimulate the ovaries to grow multiple follicles, each of which may contain an egg.
In a natural cycle, only one egg typically matures. IVF uses gonadotropins to increase the number of eggs available for retrieval, fertilization, and embryo development.
Common gonadotropin medications include:
- Follistim
- Gonal-F
- Menopur
These medications contain follicle-stimulating hormone (FSH) alone or in combination with luteinizing hormone (LH), depending on the formulation and your individual treatment plan.
IVF Gonadotropin Medications: Follistim vs Gonal-F vs Menopur
| Medication | Hormones Included | Injection Type | Typical Use in IVF | Key Differences |
|---|---|---|---|---|
| Follistim | FSH only (recombinant) | Subcutaneous | Ovarian stimulation to grow multiple follicles | Highly purified lab-made FSH; very consistent dosing; commonly used in patients with good ovarian reserve |
| Gonal-F | FSH only (recombinant) | Subcutaneous | Ovarian stimulation to grow multiple follicles | Clinically equivalent to Follistim; choice often depends on provider preference, insurance coverage, or patient response |
| Menopur | FSH + LH activity (derived from hMG) | Subcutaneous | Ovarian stimulation, often combined with FSH-only medications | Provides LH activity, which may benefit patients with diminished ovarian reserve, advanced age, or prior poor response |
How These Medications Are Commonly Used Together
Many IVF protocols combine FSH-only medications (Follistim or Gonal-F) with Menopur rather than using one medication alone. This approach allows providers to fine-tune both FSH and LH exposure based on your ovarian response, age, and fertility diagnosis.
Choosing the Right Medication
There is no universally “better” gonadotropin. The best choice depends on factors such as:
- Age and ovarian reserve
- Prior IVF response
- Hormone levels during stimulation
- Cost and insurance coverage
Your fertility specialist will select and adjust these medications throughout your cycle to optimize egg development while minimizing risks.
Injection Technique and Training
Before your first IVF cycle, you and your partner will receive detailed instructions on how to administer both subcutaneous and intramuscular injections.
A nurse coordinator may supervise your first injection to ensure proper technique and answer questions. Many clinics also provide written instructions or instructional videos to help you feel confident administering injections at home.
Most gonadotropin injections are given subcutaneously, meaning into the fatty tissue just beneath the skin, typically in the abdomen.
Baseline Ultrasound and Cycle Start
Gonadotropin injections usually begin two to three days after your period starts.
On the first day of your menstrual cycle, you’ll contact your fertility clinic to schedule a baseline ultrasound. This initial scan checks for ovarian cysts or other findings that could interfere with stimulation.
The baseline ultrasound is performed using a vaginal probe and allows your care team to assess ovarian readiness before medications begin. If cysts are present, your cycle may be delayed to optimize your response.
Ovarian Stimulation and Monitoring
Once stimulation begins, gonadotropin injections are typically taken daily.
After several days of injections, you’ll return to the clinic for follow-up ultrasounds and blood tests. These visits allow your care team to monitor follicle growth and hormone levels, particularly estradiol, which reflects how your ovaries are responding.
Medication doses may be adjusted based on your response to ensure healthy egg development while reducing the risk of ovarian hyperstimulation.
Trigger Shot and Egg Retrieval
As follicles mature, gonadotropin injections may continue for several more days.
When ultrasound and hormone testing show that the eggs are ready, you’ll receive a single human chorionic gonadotropin (hCG) injection, commonly called the trigger shot. This injection mimics the body’s natural LH surge and signals the final maturation of the eggs.
Egg retrieval is typically scheduled about 36 hours after the trigger shot. During this time, intercourse is usually avoided to prevent premature ovulation.
Progesterone Supplementation After Retrieval
Following egg retrieval and fertilization, progesterone supplementation is commonly prescribed to support the uterine lining and prepare for embryo implantation.
Progesterone may be given as injections, vaginal suppositories, creams, or oral tablets, depending on your protocol. Because progesterone can delay menstruation, pregnancy is confirmed with a blood test before discontinuing use.
IVF Gonadotropin Stimulation Timeline
| Phase | What Happens |
|---|---|
| Cycle Day 1 | Period begins, clinic is notified |
| Cycle Days 2–3 | Baseline ultrasound and labs |
| Days 2–4 | Gonadotropin injections begin |
| Days 5–10 | Continued injections with monitoring |
| Days 8–12 | Trigger shot when follicles mature |
| 36 hours later | Egg retrieval procedure |
| After retrieval | Progesterone supplementation begins |
Timing varies by individual, but most stimulation cycles last 8 to 14 days.
Gonadotropin Injections in IVF: The Bottom Line
Gonadotropin injections are a core component of IVF stimulation and are carefully tailored to your body’s response and fertility goals.
With proper instruction and close monitoring, most patients find injections manageable and well worth the effort. This approach is especially beneficial for patients pursuing IVF to maximize egg yield, improve embryo selection, and increase the chances of a successful pregnancy.
If you are considering IVF or preparing for your first stimulation cycle, your fertility team can help you understand whether gonadotropin injections are right for you and guide you through each step with confidence.
