Conception Date Accuracy
Clearblue Digital Pregnancy Test with Conception Indicator Mechanism of Action

As with other home pregnancy tests, the Clearblue Digital Pregnancy Test with Conception Indicator detects and measures human Chorionic Gonadotropin (hCG) in urine. HCG is a peptide hormone produced in pregnancy that is made by the embryo soon after conception and later by the syncytiotrophoblast (part of the placenta). Its role is to prevent the disintegration of the corpus luteum of the ovary and thereby maintain progesterone production that is critical for a pregnancy in humans. HCG is released into the blood and excreted in urine soon after implantation of the embryo. It is the marker of choice for detecting pregnancy and has a long and proven history in pregnancy testing1,2.

Structure of Intact Human
Chorionic Gonadotrophin


The Conception Indicator feature is designed to estimate the time since conception occurred. This estimate assumes that conception occurred on the day of ovulation, which is defined as the day after the urinary luteinising hormone (LH) surge. The Conception Indicator feature works on a threshold basis of urinary hCG levels: there are three time bands that give an estimate of 1-2, 2-3 and 3 or more weeks since conception. These thresholds are based on extensive research of urinary hCG rise in early pregnancy determined using the day after the LH surge as a marker for the day of conception


1.Davies S, Byrn F, Cole LA. Human chorionic gonadotropin testing for early pregnancy viability and complications. Clin Lab Med. 2003; 23(2):257-64
2. Stephenson JN. Pregnancy testing and counseling. Pediatr Clin North Am. 1989; 36(3):681-96