Pregnancy test, how accurate is this?

Today many pregnancy tests sold in the market, such us drug stores or pharmacies

According to research in the United States, the results of pregnancy test that showed negative results, does not necessarily mean the absence of pregnancy, although the use of guidelines has been undertaken correctly, this is because the process of each woman's pregnancy is different from one another.

Positive pregnancy test but not pregnant. Why?

After passing through some research, it turns out the pregnancy test kits can yield false results in detecting signs of pregnancy.

The working principle Pregnancy Test Tools

The ovum gets fused with a sperm in the fallopian tube to form a zygote. The zygote undergoes cell division for about 5-6 days. After this period, the zygote leaves the fallopian tube and moves to the uterus, where it gets implanted and undergoes further stages of pregnancy development.