What Is Chorionic Gonadotropin?
Chorionic gonadotropin, commonly called hCG (human chorionic gonadotropin), is a hormone produced by the placenta after a fertilized egg implants in the uterus. It supports early pregnancy by maintaining the corpus luteum, which produces progesterone to prevent menstruation and sustain the uterine lining.[1]
How Does hCG Confirm Pregnancy?
Pregnancy tests detect hCG in urine or blood, typically rising 6-10 days after conception. Home tests are positive around the first day of a missed period; blood tests detect it earlier (as low as 5 mIU/mL).[1][2] Levels double every 48-72 hours in early pregnancy, peaking at 8-11 weeks.
When Is hCG Produced Outside Normal Pregnancy?
hCG can appear in non-pregnant cases:
- Certain cancers (e.g., germ cell tumors, choriocarcinoma).
- Pituitary hCG in postmenopausal women.
- Rare ectopic pregnancies or molar pregnancies, where levels may be abnormally high or slow-rising.[1][3]
What If hCG Levels Are Abnormal?
Low or falling hCG after initial rise signals miscarriage, ectopic pregnancy, or blighted ovum. Doctors monitor via serial blood tests; ultrasound confirms viability around 5-6 weeks.[2][3] In men, elevated hCG prompts tumor screening.
How Is hCG Used in Fertility Treatments?
Synthetic hCG (e.g., Ovidrel, Pregnyl) triggers ovulation in IVF or injects to mimic the luteal phase surge, supporting embryo implantation.[1]
[1]: Mayo Clinic - HCG in Pregnancy
[2]: American College of Obstetricians and Gynecologists - Early Pregnancy Loss
[3]: Cleveland Clinic - hCG Levels