A pregnancy test is used to determine whether a person is pregnant or not. The two primary methods are testing for the pregnancy hormone (human chorionic gonadotropin (hCG)) in blood or urine using a pregnancy test kit, and scanning with ultrasonography. Testing blood for hCG results in the earliest detection of pregnancy. Almost all pregnant people will have a positive urine pregnancy test one week after the first day of a missed menstrual period.
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Pregnancy test in the context of Implantation (embryology)
Implantation, also known as nidation, is the stage in the mammalian embryonic development in which the blastocyst hatches, attaches, adheres, and invades into the endometrium of the female's uterus. Implantation is the first stage of gestation, and, when successful, the female is considered to be pregnant. An implanted embryo is detected by the presence of increased levels of human chorionic gonadotropin (hCG) in a pregnancy test. The implanted embryo will receive oxygen and nutrients in order to grow.
For implantation to take place the uterus must become receptive. Uterine receptivity involves much cross-talk between the embryo and the uterus, initiating changes to the endometrium. This stage gives a synchrony that opens a window of implantation that enables successful implantation of a viable embryo. The endocannabinoid system plays a vital role in this synchrony in the uterus, influencing uterine receptivity, and embryo implantation. The embryo expresses cannabinoid receptors early in its development that are responsive to anandamide (AEA) secreted in the uterus. AEA is produced at higher levels before implantation and is then down-regulated at the time of implantation. This signaling is of importance in the embryo-uterus crosstalk in regulating the timing of embryonic implantation and uterine receptivity. Adequate concentrations of AEA that are neither too high or too low, are needed for successful implantation.
Pregnancy test in the context of Human chorionic gonadotropin
Human chorionic gonadotropin (hCG) is a hormone for the maternal recognition of pregnancy produced by trophoblast cells that are surrounding a growing embryo (syncytiotrophoblast initially), which eventually forms the placenta after implantation. The presence of hCG is detected in some pregnancy tests (HCG pregnancy strip tests). Some cancerous tumors produce this hormone; therefore, elevated levels measured when the patient is not pregnant may lead to a cancer diagnosis and, if high enough, paraneoplastic syndromes, however, it is unknown whether this production is a contributing cause or an effect of carcinogenesis. The pituitary analog of hCG, known as luteinizing hormone (LH), is produced in the pituitary gland of males and females of all ages.
Beta-hCG is initially secreted by the syncytiotrophoblast.