Pregnyl is a brand name for human chorionic gonadotropin (hCG). The active ingredient in Pregnyl is the same hormone your body naturally produces during pregnancy. It is extracted and purified from the urine of pregnant women, then supplied as an injectable powder that gets mixed with a sterile solution before use.
What Pregnyl Actually Is
Pregnyl contains chorionic gonadotropin, a polypeptide hormone normally produced by the placenta. The version in Pregnyl is sometimes called “urinary hCG” (u-hCG) because of how it’s sourced. It comes as a freeze-dried powder in vials containing 10,000 international units (IU), which you or a healthcare provider reconstitute with included sterile water before injecting.
Before mixing, the powder stays stable at room temperature (59 to 86°F). Once reconstituted, the solution remains usable for 60 days when refrigerated.
How It Works in the Body
HCG mimics luteinizing hormone (LH), one of the key hormones that controls reproductive function. Because hCG and LH act on the same receptors, an injection of Pregnyl can trigger the same effects that a natural LH surge would.
In women undergoing fertility treatment, this means Pregnyl can prompt the final maturation and release of eggs from the ovaries. It also supports the corpus luteum, the temporary structure left behind after ovulation, which produces progesterone to help sustain an early pregnancy. In men with certain hormonal deficiencies, Pregnyl stimulates testosterone production and can support sperm development. In boys with undescended testicles, the testosterone surge triggered by hCG can sometimes encourage the testes to move into their normal position.
Pregnyl vs. Other HCG Brands
Pregnyl isn’t the only hCG product on the market. Novarel is another urinary-derived hCG brand that works essentially the same way. The key distinction in the hCG world is between urinary-derived products (like Pregnyl and Novarel) and recombinant hCG, which is manufactured using genetic engineering rather than extracted from urine. Ovidrel is the most well-known recombinant version.
These products contain the same hormone, but their clinical performance may not be identical. A study published in Fertility and Sterility compared Ovidrel (recombinant) against urinary-derived brands including Pregnyl and Novarel in IVF cycles. The researchers found that urinary hCG led to more eggs retrieved, a better ratio of mature eggs to follicles, and a significantly higher ongoing pregnancy rate. Based on those results, the authors recommended urinary hCG over Ovidrel to maximize IVF success. That said, Ovidrel comes in a prefilled syringe that’s more convenient, which is why some clinics still prefer it for simpler protocols like timed intercourse or intrauterine insemination.
Availability and Supply
Pregnyl is manufactured by Merck. It has periodically been placed on allocation, meaning Merck limits how much each distributor can order. The company has cited preventing diversion to gray market sellers as the reason for these restrictions. When Pregnyl supply is tight, alternatives from Fresenius Kabi and Ferring (which makes Novarel) have typically been available. If your clinic tells you Pregnyl is on backorder, these other urinary hCG products are therapeutically interchangeable.
Common Side Effects
Because hCG is a hormone your body already recognizes, most people tolerate Pregnyl well. Injection site soreness, headache, fatigue, and irritability are the most frequently reported reactions. In women using Pregnyl as part of a stimulated fertility cycle, the main concern is ovarian hyperstimulation syndrome (OHSS), a condition where the ovaries overrespond and swell, sometimes causing abdominal pain, bloating, nausea, and fluid retention. Mild OHSS is relatively common in IVF cycles and usually resolves on its own. Severe cases are rare but require medical attention.
In men and boys, side effects are generally limited to those related to the testosterone increase, such as acne or mood changes. Fluid retention can also occur at higher doses.
The Short Answer
Pregnyl is hCG. It’s one specific brand of the naturally occurring hormone, purified from human urine and delivered by injection. If you see “hCG” on a treatment protocol and your pharmacy dispenses Pregnyl, you’re getting exactly what was prescribed. The same goes if you receive Novarel or another urinary hCG product instead. The active molecule is the same.