hCG

Human chorionic gonadotropin (hCG) is a hormone produced by the cells that go on to form the placenta. After a fertilized egg implants in the uterus, hCG begins to appear in blood and then in urine, which is what home and clinical pregnancy tests measure.

Why it matters for fertility awareness#

hCG is how a possible pregnancy is first confirmed by a test. Most home tests can detect hCG in urine around the time of a missed period. Blood tests can detect it earlier and can also measure how the level changes over time, which clinicians sometimes use to evaluate early pregnancy.

How it relates to NFP#

hCG is not part of cycle tracking and is not measured by any standard NFP method. It belongs to early pregnancy, after fertilization and implantation. People who chart often combine NFP with a home pregnancy test once a luteal phase runs longer than their usual range, since a sustained high temperature pattern past about 18 days can be an early hint to test.

What it does not mean#

• hCG is not an ovulation hormone and does not appear during the fertile window.
• A faint or unclear pregnancy test should be repeated and discussed with a clinician, not interpreted alone.
• Concerns about possible pregnancy complications, bleeding, or pain should be evaluated by a clinician.

Related terms#

• Implantation, /glossary/implantation
• Luteal phase, /glossary/luteal-phase
• Progesterone, /glossary/progesterone
• Ovulation, /glossary/ovulation

Related reading#

• Can NFP help you get pregnant, /questions/can-nfp-help-you-get-pregnant
• The science of cycle tracking, /guides/science-of-cycle-tracking