Blood tests to detect pregnancy after embryo transfer are typically performed 10-14 days after the transfer, with 12 days being a common standard timeframe. This timing allows sufficient human chorionic gonadotropin (hCG) hormone to accumulate in the bloodstream for reliable detection. Testing too early—before 8-10 days—may result in false negatives since hCG levels may still be too low to measure accurately. Your fertility clinic will provide specific instructions on the exact day to test, as the timing can vary slightly depending on whether a 3-day embryo or 5-day blastocyst was transferred and individual laboratory protocols. The blood test (quantitative hCG or beta-hCG) measures the actual hormone level and is more sensitive than urine tests, making it the preferred method for confirming pregnancy after IVF. Some clinics may recommend a follow-up blood test 48 hours later to confirm that hCG levels are rising appropriately, which indicates a healthy, developing pregnancy. If you test before the recommended timeframe, you increase the risk of an inconclusive or false-negative result. Always follow your specific clinic's testing schedule for the most reliable outcome.