The trigger shot is a common injection used in fertility treatments to help women conceive. It is a carefully timed medication administered as part of procedures like intrauterine insemination (IUI) or in vitro fertilization (IVF). This shot prepares the body for the next steps in the fertility journey.
Understanding the Trigger Shot
The trigger shot contains human chorionic gonadotropin (hCG), a hormone associated with pregnancy. In fertility treatments, hCG mimics luteinizing hormone (LH), which naturally surges before ovulation. This prompts the final maturation and release of eggs from the ovaries.
The shot is precisely timed by fertility specialists, typically administered about 36 hours before an IUI procedure or an egg retrieval for IVF. This timing ensures that the eggs are mature and ready for fertilization or collection. The trigger shot is usually given as an injection either into a muscle or under the skin, and many individuals can self-administer it.
Duration in the Body
The hCG from a trigger shot gradually clears from the body. This clearance is determined by the hormone’s half-life, which is approximately 23 to 28 hours. This means that roughly every day, the amount of hCG in your system is reduced by half.
The exact duration the trigger shot remains detectable can vary based on the dosage administered and an individual’s metabolism. For instance, a 10,000 IU dose of hCG may take around 14 days to fully leave the system. Smaller doses, such as 5,000 IU or 2,500 IU, typically clear faster, often within 10 days or even a week, respectively.
Implications for Pregnancy Testing
Because the trigger shot contains hCG, the same hormone detected by home pregnancy tests, it can lead to false positive results if a test is taken too soon after the injection. Residual hCG from the shot can still be present, causing the test to show a positive line even if a pregnancy has not occurred.
To avoid a false positive, it is advised to wait until the trigger shot has cleared before taking a home pregnancy test. Many experts recommend waiting at least 10 to 14 days post-shot for a more reliable result. Waiting for a blood test at your fertility clinic, which can measure hCG levels more precisely, provides the most accurate confirmation of pregnancy.
Common Side Effects and What to Expect
After receiving a trigger shot, some individuals may experience mild and temporary side effects. These can include soreness, irritation, or redness at the injection site. Other common symptoms are bloating, mild abdominal discomfort, and breast tenderness. These reactions are associated with the body’s response to the hormones and the ovulation process.
While less common, a concern is Ovarian Hyperstimulation Syndrome (OHSS), where the ovaries become swollen and may leak fluid. Mild OHSS symptoms include abdominal pain, bloating, nausea, vomiting, or diarrhea. Severe OHSS is rare but can manifest as rapid weight gain, severe abdominal swelling, or difficulty breathing, requiring immediate medical attention. Your fertility clinic will provide specific instructions and monitor your progress to minimize risks and manage any symptoms.