Gonal-F and Menopur are combined during IVF stimulation because they supply two different hormones your ovaries need to grow mature, high-quality eggs. Gonal-F delivers pure FSH, which drives follicle growth, while Menopur adds LH activity alongside its FSH, filling a hormonal gap that FSH alone can leave open. Together, they mimic the natural teamwork of these two hormones more closely than either drug can on its own.
How FSH and LH Work Together in Your Ovaries
The rationale comes from a well-established concept in reproductive biology called the two-cell, two-gonadotropin theory. Your ovarian follicles have two layers of cells that each respond to a different hormone. LH acts on the outer layer (theca cells), stimulating them to produce androgens, a raw material. FSH then acts on the inner layer (granulosa cells), converting those androgens into estrogen through an enzyme called aromatase. Estrogen is the signal that tells your body follicles are maturing, and it helps build the uterine lining for implantation.
When you use only FSH during stimulation, your follicles can still produce some estrogen by pulling from other androgen sources in your body, like your adrenal glands. But adding LH activity ensures a richer supply of that raw material right where it’s needed, inside the follicle itself. LH also activates cellular pathways involved in cell survival and proliferation that are essential for follicular development and ovulation. The result is follicles that develop in a more physiologically complete way.
What Menopur Actually Contains
Menopur is not simply another FSH drug. Each vial contains equal parts FSH and LH activity (75 IU of each in a standard vial), but the LH activity comes almost entirely from a small amount of hCG rather than LH itself. Over 90% of Menopur’s LH activity is hCG-derived, with about 9.9 IU of hCG and only 0.4 IU of actual LH per vial. This matters because hCG binds to the same receptor as LH but with a longer-lasting effect, providing steady LH-type stimulation throughout your cycle.
Gonal-F, by contrast, is recombinant (lab-made) pure FSH with no LH activity at all. Pairing the two drugs lets your clinic dial in the exact ratio of FSH to LH your ovaries receive, something a single medication can’t offer with the same precision.
Why Clinics Adjust the Ratio for Each Patient
Your doctor chooses specific doses of each drug based largely on your ovarian reserve, often measured by AMH (anti-Müllerian hormone) levels. A commonly used dosing framework looks like this:
- Very low reserve (AMH below 1.5): 300 IU Gonal-F plus 150 IU Menopur, a high-dose protocol with significant LH supplementation
- Low-to-moderate reserve (AMH 1.6 to 2.5): 225 IU Gonal-F plus 75 IU Menopur
- Normal reserve (AMH 2.6 to 6.9): 150 IU Gonal-F plus 75 IU Menopur
- High reserve (AMH 7.0 or above): 75 IU Gonal-F plus 75 IU Menopur, a gentler protocol to reduce the risk of overstimulation
These starting doses are adjusted as early as the third day of injections, based on ultrasound measurements of your follicles and blood hormone levels. The flexibility of a two-drug protocol is one of its key advantages: your clinic can increase FSH without adding more LH, or vice versa, fine-tuning stimulation in a way that a single medication doesn’t allow.
Who Benefits Most From the Combination
The combination tends to matter most for women with diminished ovarian reserve. A large real-world study found that adding LH supplementation to FSH significantly improved cumulative live birth rates for women with moderate to severe poor ovarian response. For women with only mildly reduced reserve, the benefit was less clear. Interestingly, for women of advanced maternal age (35 to 40) without other poor-response markers, pregnancy and live birth rates were similar whether or not LH was added.
Women with low ovarian reserve or certain receptor variations may not respond fully to FSH alone. In these cases, adding LH helps ensure follicles reach full maturity and that ovulation happens in a more coordinated way. For patients with normal ovarian function, the combination still offers the advantage of a more physiologic hormone environment, though the difference in outcomes may be smaller.
Effects on Egg Quality and Stimulation Length
Adding LH activity doesn’t just grow more follicles. Research suggests it improves the quality of the eggs inside them. Studies show that more LH activity during the middle phase of follicle growth is associated with better egg quality, and that implantation rates improve when LH is added during antagonist cycles (one of the most common IVF protocols).
There’s also a practical efficiency gain. When graded levels of LH activity were added to a fixed FSH dose in clinical studies, stimulation cycles became shorter and required less total FSH. The two hormones appear to have a synergistic effect: LH makes FSH work more effectively, which can mean fewer days of injections and lower medication costs overall.
How Outcomes Compare to FSH Alone
A landmark European-Israeli trial (EISG) compared Menopur head-to-head with Gonal-F alone in over 700 IVF patients. In the subgroup of 233 women who underwent standard IVF, the ongoing pregnancy rate was 31% in the Menopur group compared to 20% in the Gonal-F-only group, a statistically significant difference. The trial was originally designed to show that Menopur was “not worse” than Gonal-F, but the IVF subgroup actually showed it was better.
These numbers come from using Menopur alone versus Gonal-F alone, but they illustrate the value of LH activity during stimulation. Most clinics today combine both drugs rather than choosing one, capturing the high FSH output of Gonal-F alongside the LH activity of Menopur. This combined approach gives your doctor the most control over your hormonal environment while keeping the biological benefits of both hormones in play.