During IVF treatment, your doctor would advise you to do blood test (Bhcg) of pregnancy usually after 2 weeks of embryo transfer. We know that 2 weeks wait is hard, but if you test too early both false positive and false negative results may occur, which is why it is best to wait until the day of your scheduled blood test at your fertility clinic.
Why Wait Two Weeks?
There’s a reason you need to wait two weeks for an accurate pregnancy test. Pregnancy tests measure the level of hCG (human chorionic gonadotropin), the pregnancy hormone. The body starts producing hCG when an embryo implants in the uterus. However, it takes about two weeks to produce enough hormones to be detected. Remember, the conception process takes time. The problem with home pregnancy tests is that, if you take them early, the results are not reliably accurate. Home pregnancy tests set a specific level of hCG in the urine to produce a positive reading. However, if the level of hCG in your urine has not yet reached that point, then the result will be negative, even if you are pregnant. Of course, you may be wondering why you get a positive reading for pregnancy when you are not pregnant. The reason is that women undergoing fertility treatments are given hCG to trigger ovulation. Typically, traces of hCG remain in your system for eight to ten days after the trigger shot. If you take a pregnancy test early, residual hCG from the trigger shot will be picked up by the test and indicate you are pregnant when you are not, a false positive reading.
Why & when HCG shots required in IVF
HCG injection is given in the final phase of infertility treatments, for maturing of eggs (ovulation). Ovulation is the rupture of the graffian follicles to release the egg. After taking the HCG shots, it takes another 36-40 hrs for ovulation to occur. During IVF, this HCG It takes about 10 days for this huge amount of HCG to decline in the blood. Some centres also advise hCG injections post embryo transfer for supporting a possible pregnancy, ie luteal phase support. Any urine or blood pregnancy test done within 10 days of this injection would give a positive result, when in reality it would just be a false positive test. Hence, the test interpretation should be done keeping these confounding factors in mind.
Beta hCG Blood Test
The Beta hCG Blood Test is the test your doctor will perform to determine if you are pregnant. Just like a home pregnancy test, it measures hCG. However, unlike home tests, the Beta test measures hCG levels in your blood rather than the urine and is more accurate. But, just like the home pregnancy test, the Beta test requires the two-week wait to ensure accuracy.