Final answer:
Home pregnancy tests detect the hormone human chorionic gonadotropin (hCG), which is produced after the implantation of the embryo. The test has a control line to ensure it's working and a test line that appears when hCG is present, indicating pregnancy.
Step-by-step explanation:
Pregnancy tests are designed to detect a specific hormone known as human chorionic gonadotropin (hCG). This hormone is produced by the cells of the embryo that will later form the placenta. After implantation, levels of hCG can be detected in the blood and urine of pregnant individuals. The presence of hCG is what a pregnancy test looks for when determining if someone is pregnant.
The typical home pregnancy test has a control line and a test line. The control line appears when the test is working correctly, while the appearance of a test line indicates that hCG has been detected in urine. The development of the test line indicates a positive test result, suggesting pregnancy.
Pregnancy causes the secretion of not only hCG but also progesterone and estrogens, which are crucial in maintaining and supporting the developing pregnancy. These hormones contribute to the changes a pregnant individual's body undergoes through gestation.