For couples struggling with infertility, ovulation timing is everything. Doctors use a hormone called HCG (Human Chorionic Gonadotropin) to help control and trigger ovulation in fertility treatments. But how exactly does it work?
HCG mimics the body’s natural LH (Luteinizing Hormone) surge, which triggers the final maturation and release of the egg from the ovary.
This single shot often decides whether ovulation will happen at the right time, especially in Ivermectin Online and IUI cycles. Keep reading to understand how this process works and why it’s critical to success in assisted reproduction.
What Is HCG and Why Is It Used in Fertility Treatment?
HCG is a natural hormone produced during pregnancy. In fertility treatments, synthetic or urinary-extracted HCG is used to trigger ovulation.
- HCG activates the LH receptors on ovarian follicles.
- This induces the final maturation of the egg.
- Ovulation typically occurs within 36–40 hours after HCG Online injection.
- It helps with procedures like IUI or egg retrieval in IVF.
In simple terms, HCG replaces the body’s own LH surge to ensure predictable ovulation.
How Does HCG Mimic the Natural LH Surge?
The luteinizing hormone (LH) is responsible for triggering ovulation mid-cycle. HCG has a similar molecular structure and binds to the same LH receptors. When HCG is injected:
- HCG signals the follicle to resume meiosis (egg maturation).
- It triggers ovulatory mechanisms, releasing the egg from the dominant follicle.
- Also, it stimulates the corpus luteum formation, which supports early pregnancy.
Because of its longer half-life, HCG stays in the body longer than LH, giving doctors more control over ovulation timing.
When Is HCG Given in a Fertility Cycle?
Timing is critical. HCG is usually administered when the leading follicle reaches 17–20 mm in size, confirmed by ultrasound.
Doctors give the HCG injection:
- In ovulation induction cycles (with Clomid or Letrozole)
- During IUI cycles, to sync intercourse or insemination
- Before IVF egg retrieval, to time the extraction of mature eggs
Once HCG is given, ovulation usually happens in 36 hours, so procedures are carefully scheduled within that window.
What Happens in the Body After an HCG Injection?
After an HCG injection, the hormone triggers several important changes inside the ovary. It helps the egg complete its final maturation, causes the follicle to rupture for ovulation, and supports the formation of the corpus luteum, which produces progesterone to prepare the uterine lining. Together, these processes create the ideal environment for natural conception or successful embryo implantation.
Is HCG Used in IVF Different From Natural Cycles?
Yes, the use of HCG in IVF is more controlled. In IVF:
- HCG is used to trigger egg maturation, not natural ovulation.
- Doctors time the egg retrieval exactly 34–36 hours after injection.
- If ovulation occurs too early, eggs may be lost; if it occurs too late, they may be overripe.
This is why HCG timing in IVF is strictly monitored, often combined with other medications like GnRH antagonists to prevent premature LH surges.
Are There Any Side Effects or Risks of Using HCG?
While HCG is generally safe, it can have some side effects, especially in high-response cycles.
Common effects include:
- Bloating or abdominal discomfort
- Mild nausea
- Headaches
- Risk of OHSS (Ovarian Hyperstimulation Syndrome) in sensitive patients
Doctors carefully monitor hormone levels and follicle count before giving HCG to minimise these risks.
Can You Confirm Ovulation After the HCG Shot?
Yes, ovulation can be confirmed using several methods:
- Ultrasound: Checking for follicle collapse
- Progesterone test: A blood test 7 days after ovulation
- BBT (Basal Body Temperature): A rise indicates ovulation occurred
Also, ovulation predictor kits (OPKs) may stay positive after HCG injection due to cross-reactivity, so they aren’t reliable post-shot.
Summary: Why HCG Is Essential in fertility treatments
HCG plays a central role in fertility treatments by mimicking LH, controlling ovulation timing, and ensuring egg maturation. Its use helps align procedures like IUI and IVF with the body’s reproductive timeline, improving the chances of conception.
