When should I take the HPT to get the most accurate result?

Current HPTs are advertised as being sensitive on the first day of a missed period—or perhaps a few days before. The most recent review of accuracy of HPTs, published in August of 2011, tested these claims. One brand, First Response, detected 97% of pregnancies on the first day of a missed period. The EPT manual (54%) and digital (67%) and the Clear Blue manual (64%) and digital (54%) tests all detected fewer actual pregnancies. These results may reflect that the First Response could detect as little as 5.5 mIU/ml of hCG in the urine while the other two brands could detect 22 mIU/ml. Generally speaking, a reliable pregnancy test in a doctor’s office should be able to detect a level of 22 units of hCG or higher.

Remember, it takes an implantation to produce hCG to trigger a test. In a study where the day of implantation was documented with a sensitive blood test, it was determined that 10% of viable pregnancies were not yet implanted by the first day of the missed period!

Having read all this you can now understand why a GYN may recommend using a HPT twice, if the first instance is at the time of a missed period. About 97% of viable pregnancies will have implanted by seven days after the first day of missed menses. Taking a second reading can also enhance accuracy where your HPT is not one of the super-sensitive brands.