current home pregnancy tests (hpts) are advertised to be sensitive on the first day of a missed period—or perhaps a few days before. in the most recent review of accuracy of hpts published in august of 2011 such claims were tested. 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 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 missed flow. 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.
had sex on fertile days when should i check if pregnant?