When you are pregnant, your body begins to produce the hormone human chorionic gonadotropin (HCG). HCG is produced by the placenta during pregnancy, and is the hormone that a home pregnancy test detects. Your body begins to produce HCG about six days after an egg is fertilized and after the embryo implants in the uterus. Levels of HCG increase rapidly in a pregnant woman’s body and are detectable in urine. By the time you think you may be pregnant (usually after you miss your period), HCG levels are high enough that a home pregnancy test will detect them.
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